Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

There are some designs for harmonic reducers that use a rubber timing belt
as the flexible gear.   It seems like these might last nearly forever.

But 99% of the stuff on Thingiverse needs for development work.   People
post their project as soon as they reach the "demo" stage and they are
mostly not finished products, just some guy's experiment.   So you should
expect to need to modify and redesign a few more interactions.

That is the neat thing about open source, if it doesn't work you can change
it.

So, there are quite a few demos that use timing belts

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gregg Eshelman via Emc-users]

What's the thingiverse link again? Quite a number of these things on there. All 
messages with it have flushed from Yahoo's trash folder. Now my interest is 
piqued more and I want to see the models you're working with. 

On Monday, August 24, 2020, 7:54:55 PM MDT, Gene Heskett 
 wrote:  
 On Monday 24 August 2020 19:43:22 Thaddeus Waldner wrote:

> A print with sturdy walls and mostly hollow interior describes a
> diaphragm structure. This is great for when you need a stiff part, but
> not so great for flex. What you need to do to get maximum strength and
> flexibility is to print the flex part solid and thin it from the
> outside.
>
My version would be a bit more OOTB, to thin the base to add more flex to 
the bottom of this cup. But I'm still figuring out cura. The walls being 
flexed seems to translate to an up and down deformation of the bottom of 
this "cup" and a thinner bottom might reduce the strain on the sidewall 
junction where it usually breaks. Done and resliced. The current copy 
I'm about to kill is bridging the bolt holes.  There is nothing above 
them, so why?  Turned it off. Took 2 layers out of the bottom, I think. 
With cura, who knows for sure?  Anyway, its building. And about an hour 
and change faster.  
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gregg Eshelman via Emc-users]

 Some sort of flexibility enhancing slots might work. Perhaps a couple of rows 
of this sort of slot horizontally around the circumference? 
https://hackaday.com/2011/12/07/laser-cutting-technique-makes-plywood-bendable/

On Monday, August 24, 2020, 5:45:47 PM MDT, Thaddeus Waldner 
 wrote:  
 A print with sturdy walls and mostly hollow interior describes a diaphragm 
structure. This is great for when you need a stiff part, but not so great for 
flex. What you need to do to get maximum strength and flexibility is to print 
the flex part solid and thin it from the outside. 


> On Aug 24, 2020, at 4:14 PM, Gene Heskett  wrote:
> 
> On Monday 24 August 2020 06:15:16 andy pugh wrote:
> 
>> On Mon, 24 Aug 2020 at 10:35, Gene Heskett  
> wrote:
>>> I hadn't thought of that, changing filament is a pita, but worth the
>>> experiment.
>> 
>> I think that I would be looking to  change the design. Where is it
>> breaking?
>> 
> Most of the time right at the junction of the fillet at the edge of the 
> bottom disk, so the separation is at the first layer of wall.  However, 
> if the bearings size is adjusted so the splines are fully engaged, then 
> the breakage seems to correspond to the root of the spline.
> 
> Best lifetime before breakage corresponds to what I would call about 90% 
> engagement at the maximum, and a hop clearance at maximum pullin between 
> the bearings that doesn't result in a click as they hop over each other.  
> Half the tooth height for clearance is still too much flex, and will 
> break it in under 30 minutes if left running at 4 or 5 rpm at the 
> output.
> 
> Definitely needs a filament with more elasticity than PLA. What TPU I've  
> seen on you-tube is way too much though.
> 
> Cura's original wall count was 2, but that breaks by the time the motor 
> has turned 2 full turns.  At 6, its better but is beginning to effect 
> the motors ability to turn it at about an amp a coil drive. The TB6560 
> doesn't map its coils well for microstepping which results in its 
> running at a fractionally slower rpm unless I stop it and restart it 
> from the function generators dials, effectively bringing it up from zero 
> speed.  But thats this crappy drivers fault. Thats why you can buy this 
> POS for about $6/copy on fleabay.  What we need is a 2M542 for about 2 
> amps.
> 
> Yep, a better design and some more flexible plastic is needed. Like Yogi 
> Berra said, is so true.  This one needs a bigger pair of main bearings 
> too.
> 
> That said I found I was gonna be late writing a check for the Missus's 
> keep, so I started a flexgear and got in the truck to go do that. Bout 
> an 85 or 86 mile round trip.
> 
> On arrival back here it had a clogged nozzle, so I killed that, cleaned 
> the nozzle and rethreaded it, getting some flow at 180C.  So that might 
> be a minimum temp sometime. Resliced it, taking a few more defaults, 
> getting the build time down to 10 something hours and restarted another 
> flexgear.
> 
> This keeps me out of the bars.  You can get stuff in a bar, that they 
> don't have a pill for.  
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

THat is a great idea but did you see the designer's disclaimer?   It
reads

 I printed mine out of PLA and after about 15 minutes of high-speed use,
> the flexible gear cracked. Printing out of other materials may give a
> longer life, but really, any 3D printed gears are not really suitable for
> high speed or extended use.


I kind of disagree.   If you print spur gears large enough they last for
years.  I'm using modulo 2.0 gears in PLA for a system that is powered by a
NEMA23 motor.  It will last for years.

Another idea is to use TPU in place of the flex beams.  Or better by far is
a poured in polyurethane.Ir filling the space with silicone seal.

On Mon, Aug 24, 2020 at 3:20 AM andy pugh  wrote:

> On Mon, 24 Aug 2020 at 10:35, Gene Heskett  wrote:
>
> > I hadn't thought of that, changing filament is a pita, but worth the
> > experiment.
>
> I think that I would be looking to  change the design. Where is it
> breaking?
>
> If you look at some other designs they incorporate flex-beams.
> https://www.thingiverse.com/thing:2951164
> (Not the same type of harmonic drive, it uses two internal gears with
> the same diameter but different tooth counts)
> I think that the way to make the one you have more robust will be to
> make the strain gear more flexible (lower wall count, lower infil,
> probably the reverse of what you have been doing)
>
> --
> atp
> "A motorcycle is a bicycle with a pandemonium attachment and is
> designed for the especial use of mechanical geniuses, daredevils and
> lunatics."
> — George Fitch, Atlanta Constitution Newspaper, 1912
>
>
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>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Monday 24 August 2020 19:43:22 Thaddeus Waldner wrote:

> A print with sturdy walls and mostly hollow interior describes a
> diaphragm structure. This is great for when you need a stiff part, but
> not so great for flex. What you need to do to get maximum strength and
> flexibility is to print the flex part solid and thin it from the
> outside.
>
My version would be a bit more OOTB, to thin the base to add more flex to 
the bottom of this cup. But I'm still figuring out cura. The walls being 
flexed seems to translate to an up and down deformation of the bottom of 
this "cup" and a thinner bottom might reduce the strain on the sidewall 
junction where it usually breaks. Done and resliced. The current copy 
I'm about to kill is bridging the bolt holes.  There is nothing above 
them, so why?  Turned it off. Took 2 layers out of the bottom, I think. 
With cura, who knows for sure?  Anyway, its building. And about an hour 
and change faster.

And we'll see what, if any diff, it makes tommorrow.

> > On Aug 24, 2020, at 4:14 PM, Gene Heskett 
> > wrote:
> >
> > On Monday 24 August 2020 06:15:16 andy pugh wrote:
> >> On Mon, 24 Aug 2020 at 10:35, Gene Heskett 
> >
> > wrote:
> >>> I hadn't thought of that, changing filament is a pita, but worth
> >>> the experiment.
> >>
> >> I think that I would be looking to  change the design. Where is it
> >> breaking?
> >
> > Most of the time right at the junction of the fillet at the edge of
> > the bottom disk, so the separation is at the first layer of wall. 
> > However, if the bearings size is adjusted so the splines are fully
> > engaged, then the breakage seems to correspond to the root of the
> > spline.
> >
> > Best lifetime before breakage corresponds to what I would call about
> > 90% engagement at the maximum, and a hop clearance at maximum pullin
> > between the bearings that doesn't result in a click as they hop over
> > each other. Half the tooth height for clearance is still too much
> > flex, and will break it in under 30 minutes if left running at 4 or
> > 5 rpm at the output.
> >
> > Definitely needs a filament with more elasticity than PLA. What TPU
> > I've seen on you-tube is way too much though.
> >
> > Cura's original wall count was 2, but that breaks by the time the
> > motor has turned 2 full turns.  At 6, its better but is beginning to
> > effect the motors ability to turn it at about an amp a coil drive.
> > The TB6560 doesn't map its coils well for microstepping which
> > results in its running at a fractionally slower rpm unless I stop it
> > and restart it from the function generators dials, effectively
> > bringing it up from zero speed.  But thats this crappy drivers
> > fault. Thats why you can buy this POS for about $6/copy on fleabay. 
> > What we need is a 2M542 for about 2 amps.
> >
> > Yep, a better design and some more flexible plastic is needed. Like
> > Yogi Berra said, is so true.  This one needs a bigger pair of main
> > bearings too.
> >
> > That said I found I was gonna be late writing a check for the
> > Missus's keep, so I started a flexgear and got in the truck to go do
> > that. Bout an 85 or 86 mile round trip.
> >
> > On arrival back here it had a clogged nozzle, so I killed that,
> > cleaned the nozzle and rethreaded it, getting some flow at 180C.  So
> > that might be a minimum temp sometime. Resliced it, taking a few
> > more defaults, getting the build time down to 10 something hours and
> > restarted another flexgear.
> >
> > This keeps me out of the bars.  You can get stuff in a bar, that
> > they don't have a pill for.
> >
> >> If you look at some other designs they incorporate flex-beams.
> >> https://www.thingiverse.com/thing:2951164
> >> (Not the same type of harmonic drive, it uses two internal gears
> >> with the same diameter but different tooth counts)
> >> I think that the way to make the one you have more robust will be
> >> to make the strain gear more flexible (lower wall count, lower
> >> infil, probably the reverse of what you have been doing)
> >
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> > soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > If we desire respect for the law, we must first make the law
> > respectable. - Louis D. Brandeis
> > Genes Web page 
> >
> >
> > ___
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> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 

Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Thaddeus Waldner]

A print with sturdy walls and mostly hollow interior describes a diaphragm 
structure. This is great for when you need a stiff part, but not so great for 
flex. What you need to do to get maximum strength and flexibility is to print 
the flex part solid and thin it from the outside. 


> On Aug 24, 2020, at 4:14 PM, Gene Heskett  wrote:
> 
> On Monday 24 August 2020 06:15:16 andy pugh wrote:
> 
>> On Mon, 24 Aug 2020 at 10:35, Gene Heskett  
> wrote:
>>> I hadn't thought of that, changing filament is a pita, but worth the
>>> experiment.
>> 
>> I think that I would be looking to  change the design. Where is it
>> breaking?
>> 
> Most of the time right at the junction of the fillet at the edge of the 
> bottom disk, so the separation is at the first layer of wall.  However, 
> if the bearings size is adjusted so the splines are fully engaged, then 
> the breakage seems to correspond to the root of the spline.
> 
> Best lifetime before breakage corresponds to what I would call about 90% 
> engagement at the maximum, and a hop clearance at maximum pullin between 
> the bearings that doesn't result in a click as they hop over each other.  
> Half the tooth height for clearance is still too much flex, and will 
> break it in under 30 minutes if left running at 4 or 5 rpm at the 
> output.
> 
> Definitely needs a filament with more elasticity than PLA. What TPU I've  
> seen on you-tube is way too much though.
> 
> Cura's original wall count was 2, but that breaks by the time the motor 
> has turned 2 full turns.  At 6, its better but is beginning to effect 
> the motors ability to turn it at about an amp a coil drive. The TB6560 
> doesn't map its coils well for microstepping which results in its 
> running at a fractionally slower rpm unless I stop it and restart it 
> from the function generators dials, effectively bringing it up from zero 
> speed.  But thats this crappy drivers fault. Thats why you can buy this 
> POS for about $6/copy on fleabay.  What we need is a 2M542 for about 2 
> amps.
> 
> Yep, a better design and some more flexible plastic is needed. Like Yogi 
> Berra said, is so true.  This one needs a bigger pair of main bearings 
> too.
> 
> That said I found I was gonna be late writing a check for the Missus's 
> keep, so I started a flexgear and got in the truck to go do that. Bout 
> an 85 or 86 mile round trip.
> 
> On arrival back here it had a clogged nozzle, so I killed that, cleaned 
> the nozzle and rethreaded it, getting some flow at 180C.  So that might 
> be a minimum temp sometime. Resliced it, taking a few more defaults, 
> getting the build time down to 10 something hours and restarted another 
> flexgear.
> 
> This keeps me out of the bars.  You can get stuff in a bar, that they 
> don't have a pill for.
> 
>> If you look at some other designs they incorporate flex-beams.
>> https://www.thingiverse.com/thing:2951164
>> (Not the same type of harmonic drive, it uses two internal gears with
>> the same diameter but different tooth counts)
>> I think that the way to make the one you have more robust will be to
>> make the strain gear more flexible (lower wall count, lower infil,
>> probably the reverse of what you have been doing)
> 
> 
> Cheers, Gene Heskett
> -- 
> "There are four boxes to be used in defense of liberty:
> soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
> - Louis D. Brandeis
> Genes Web page 
> 
> 
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> https://lists.sourceforge.net/lists/listinfo/emc-users



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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Monday 24 August 2020 06:15:16 andy pugh wrote:

> On Mon, 24 Aug 2020 at 10:35, Gene Heskett  
wrote:
> > I hadn't thought of that, changing filament is a pita, but worth the
> > experiment.
>
> I think that I would be looking to  change the design. Where is it
> breaking?
>
Most of the time right at the junction of the fillet at the edge of the 
bottom disk, so the separation is at the first layer of wall.  However, 
if the bearings size is adjusted so the splines are fully engaged, then 
the breakage seems to correspond to the root of the spline.

Best lifetime before breakage corresponds to what I would call about 90% 
engagement at the maximum, and a hop clearance at maximum pullin between 
the bearings that doesn't result in a click as they hop over each other.  
Half the tooth height for clearance is still too much flex, and will 
break it in under 30 minutes if left running at 4 or 5 rpm at the 
output.

Definitely needs a filament with more elasticity than PLA. What TPU I've  
seen on you-tube is way too much though.

Cura's original wall count was 2, but that breaks by the time the motor 
has turned 2 full turns.  At 6, its better but is beginning to effect 
the motors ability to turn it at about an amp a coil drive. The TB6560 
doesn't map its coils well for microstepping which results in its 
running at a fractionally slower rpm unless I stop it and restart it 
from the function generators dials, effectively bringing it up from zero 
speed.  But thats this crappy drivers fault. Thats why you can buy this 
POS for about $6/copy on fleabay.  What we need is a 2M542 for about 2 
amps.

Yep, a better design and some more flexible plastic is needed. Like Yogi 
Berra said, is so true.  This one needs a bigger pair of main bearings 
too.

That said I found I was gonna be late writing a check for the Missus's 
keep, so I started a flexgear and got in the truck to go do that. Bout 
an 85 or 86 mile round trip.

On arrival back here it had a clogged nozzle, so I killed that, cleaned 
the nozzle and rethreaded it, getting some flow at 180C.  So that might 
be a minimum temp sometime. Resliced it, taking a few more defaults, 
getting the build time down to 10 something hours and restarted another 
flexgear.

This keeps me out of the bars.  You can get stuff in a bar, that they 
don't have a pill for.

> If you look at some other designs they incorporate flex-beams.
> https://www.thingiverse.com/thing:2951164
> (Not the same type of harmonic drive, it uses two internal gears with
> the same diameter but different tooth counts)
> I think that the way to make the one you have more robust will be to
> make the strain gear more flexible (lower wall count, lower infil,
> probably the reverse of what you have been doing)


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[andy pugh]

On Mon, 24 Aug 2020 at 10:35, Gene Heskett  wrote:

> I hadn't thought of that, changing filament is a pita, but worth the
> experiment.

I think that I would be looking to  change the design. Where is it breaking?

If you look at some other designs they incorporate flex-beams.
https://www.thingiverse.com/thing:2951164
(Not the same type of harmonic drive, it uses two internal gears with
the same diameter but different tooth counts)
I think that the way to make the one you have more robust will be to
make the strain gear more flexible (lower wall count, lower infil,
probably the reverse of what you have been doing)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Les Newell]

I've done a fair amount of plastic welding and generally dissimilar 
plastics don't like to heat bond to each other. The join is usually very 
weak. It's worth a try though.


Les

On 24/08/2020 04:41, Gregg Eshelman via Emc-users wrote:

Something to try when you get a roll of TPU. First do some test cube 
experiments to figure out how to pause and swap filament for a few layers, then 
pause and swap back. Then figure out the settings to get TPU and PLA to bond 
together.
Print the part with a few layers of TPU bracketing the level where it keeps 
breaking.

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 23 August 2020 23:41:59 Gregg Eshelman via Emc-users wrote:

> Something to try when you get a roll of TPU. First do some test cube
> experiments to figure out how to pause and swap filament for a few
> layers, then pause and swap back. Then figure out the settings to get
> TPU and PLA to bond together. Print the part with a few layers of TPU
> bracketing the level where it keeps breaking.
>
I hadn't thought of that, changing filament is a pita, but worth the 
experiment.  Thanks Gregg.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gregg Eshelman via Emc-users]

Something to try when you get a roll of TPU. First do some test cube 
experiments to figure out how to pause and swap filament for a few layers, then 
pause and swap back. Then figure out the settings to get TPU and PLA to bond 
together.
Print the part with a few layers of TPU bracketing the level where it keeps 
breaking.

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 23 August 2020 19:00:51 Bruce Layne wrote:

> On 8/23/20 4:32 PM, Gene Heskett wrote:
> > The TPU hasn't arrived, and its way too
> > flexible for this from what I've found on you-tube.  Wait for a
> > different design to show up. From what I've learned, the cup of the
> > flexgear could be doubled in depth aspect ratio. Or we need a
> > plastic with more flexability, and tpu isn't it.  ABS maybe, its
> > pretty tough stuff. And higher priced too.
>
> I'd advise printing some object such as a tire ("tyre" for Andy) using
> TPU, 90 or 95 on the Shore A scale.  Print it with four outer layers
> and 20% infill.  You'll have a tough and durable part with some
> compliance. Print the same part with one outer layer and 10% infill. 
> You'll have a very soft and flexible part.  TPU offers a large range
> of physical properties, in part because of different durometers of the
> filament, typically 85-98 on the Shore A scale, but much more as a
> result of the part geometry, number of outer layers and infill
> percentage.
>
> ABS might be a good choice if you need toughness and PLA is too
> brittle.  Like TPU, the part geometry and slicer settings can greatly
> alter the physical properties.  ABS is not inherently more expensive
> than PLA, or at least not significantly so.  I previously sent a link
> to a source of excellent quality ABS filament for 1.62 cents per gram,
> delivered in the US.
>
If the tpu ever shows up, I'll be back hat in hand for recommendations. 
But I'm a sucker, so I've got another drive running, on teeth that are 
still starved.  So I've raised the steps/mm from 290 to 315, but as soon 
as it was started, I ran the tune/flow back up to 120% to get rid of the 
skips in the laydown.

One thing of note is that the way the micro-swiss extruder is built, the 
8.5mm retraction I was useing to stop the stringing in older slices is 
excessive as it pulls hot plastic back far enough to gradually create an 
extruder blockage by pulling it back far enough to cool it.  They 
recommend not more than 2.5mm retract.  I think I'm going to like this 
design, once I learn its foibles.  But it does tend to big drop starts, 
and stringing. So parts need more cleanup with a sharp tool.

Thanks Bruce.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Bruce Layne]

On 8/23/20 4:32 PM, Gene Heskett wrote:
> The TPU hasn't arrived, and its way too 
> flexible for this from what I've found on you-tube.  Wait for a 
> different design to show up. From what I've learned, the cup of the 
> flexgear could be doubled in depth aspect ratio. Or we need a plastic 
> with more flexability, and tpu isn't it.  ABS maybe, its pretty tough 
> stuff. And higher priced too.

I'd advise printing some object such as a tire ("tyre" for Andy) using
TPU, 90 or 95 on the Shore A scale.  Print it with four outer layers and
20% infill.  You'll have a tough and durable part with some compliance. 
Print the same part with one outer layer and 10% infill.  You'll have a
very soft and flexible part.  TPU offers a large range of physical
properties, in part because of different durometers of the filament,
typically 85-98 on the Shore A scale, but much more as a result of the
part geometry, number of outer layers and infill percentage.

ABS might be a good choice if you need toughness and PLA is too
brittle.  Like TPU, the part geometry and slicer settings can greatly
alter the physical properties.  ABS is not inherently more expensive
than PLA, or at least not significantly so.  I previously sent a link to
a source of excellent quality ABS filament for 1.62 cents per gram,
delivered in the US.

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 23 August 2020 14:59:11 Chris Albertson wrote:

> You are pretty much confirming my opinion that you know more about
> these than the guy who designed the one you are trying to build.
>
> Some of my first projects were a box to house a PCB, A plastic foot to
> a stand mixer.  and a rear cap for an SLR lens.  And other things that
> don't matter if the tolerance is off by 0.5mmThen you work up to
> more complex stuff.
>
> The key is to develop CAD skills or you are at the mercy of random
> people who post to Thingverse and the quality there is all over the
> map.
>
> The key to printing machine parts is to never depend on precision. 
> I'll place a screw adjustment on a shaft to shaft distance and then I
> can adjust the tightness of the gears after assembly.   Precision
> holes are printed undersize then bored or reamed.One way is to
> treat printed parts as if they were raw castings.
>
> I'm starting another project soon, it will be an open-source robot
> that is modular, lego-like with wheels about 200mm diameter.   We are
> designing this collaboratively with the idea that it by easy to print,
> even on low-end out of spec printers.   We'll use 8mm drill rod axels
> and skate bearings.
>
> Long terms is a four-leg robot that is sized large enough to do normal
> stairs and have an eye-level high enough off the floor to navigate a
> normal house. Perhaps like a small dog.   The key is being
> buildable by amateurs with limited tools and experience.   The wheeled
> version goes first.  The legged version needs 12 reduction drives.  
> You can see my interest in reading about your problems with this.

Yes, I got that from reading between the lines, Chris. :) But I just 
destroyed two more flexgears quicker than I can make them, took about 3 
hours running at 5 or 7 rpms out to break the last one and it had plenty 
of hop room.  So while the white pla might feel a hair more flexible, 
over the long haul it fatigue cracks just as fast as the black stuff. So 
far I've got one that has run 24 hours, but it also has a degree of 
backlash.  Thats not good enough for a Stellarium drive.

So after the one on the build plate now has self destructed, I think I'll 
bag up all the bearings and go back to making a 100/1 worm drive work on 
the BS-1 clone. Its been a learning experience, but I've also wasted at 
least $1000+ and 2 months.  The TPU hasn't arrived, and its way too 
flexible for this from what I've found on you-tube.  Wait for a 
different design to show up. From what I've learned, the cup of the 
flexgear could be doubled in depth aspect ratio. Or we need a plastic 
with more flexability, and tpu isn't it.  ABS maybe, its pretty tough 
stuff. And higher priced too. And I need a way to calibrate the extruder 
on the micro-swiss hot end kit.  They recommend a starter setting of 130 
steps/mm, and I am getting close at 320/mm.

> On Sat, Aug 22, 2020 at 9:26 PM Gene Heskett  
wrote:
> > On Saturday 22 August 2020 19:25:25 Chris Albertson wrote:
> > > Then go into the CAD software and fill the hex pocket and enlarge
> > > the holes to accept the brass inserts or make models threads.
> > >
> > > At some point to you have to decide that the person who designed
> > > this thing only made a first level prototype and more development
> > > is required.   I'm following your story and I would have made that
> > > determination weeks ago. It is a good fist try, to prove it might
> > > work but they break quickly and seem to be very hard to print.   
> > > My guess is that a few more design iterations are needed.  To make
> > > them easier to print and stronger.
> > >
> > > I think there might be trade-offs reduction ratio and backlash and
> > > strength and "printability"
> > >
> > > I had a professor once who said you can always tell a new or
> > > amateur engineer because the stuff he designs only works if you
> > > use non-standard high precision parts.  Better designs don't need
> > > any of that.  Designing things that work and are printable is
> > > hard.  Easier to design stuff in metal with 0.0001 level specs.  
> > > This designer was tinking in metal but using plastic.
> >
> > Tinking, could be thinking or tinkling. I'm in favor of calling it
> > the latter.
> >
> > "gear ratio" in the case of a harmonic drive, is a huge compromise,
> > tradeoff if you will, between the ratio and the amount of flex
> > imparted to the flexible member, lower ratios mean taller, wider
> > "teeth" and more flex.  Higher ratios need smaller "teeth" and
> > correspondingly less flexing. And this one has about the maximum
> > flex the plastic will allow without rapid fatigue cracking and
> > failure.  Go for too small and you are going to exceed the tolerance
> > of your machine to lay up an accurate representation of what the
> > optimum design needs.  And this design may be right on the ragged
> > edge. So the exact size of each of the three working parts must meet
> > the following criteria:
> >
> > 1. 

Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

You are pretty much confirming my opinion that you know more about these
than the guy who designed the one you are trying to build.

Some of my first projects were a box to house a PCB, A plastic foot to a
stand mixer.  and a rear cap for an SLR lens.  And other things that don't
matter if the tolerance is off by 0.5mmThen you work up to more complex
stuff.

The key is to develop CAD skills or you are at the mercy of random people
who post to Thingverse and the quality there is all over the map.

The key to printing machine parts is to never depend on precision.  I'll
place a screw adjustment on a shaft to shaft distance and then I can adjust
the tightness of the gears after assembly.   Precision holes are printed
undersize then bored or reamed.One way is to treat printed parts as if
they were raw castings.

I'm starting another project soon, it will be an open-source robot that is
modular, lego-like with wheels about 200mm diameter.   We are designing
this collaboratively with the idea that it by easy to print, even on
low-end out of spec printers.   We'll use 8mm drill rod axels and skate
bearings.

Long terms is a four-leg robot that is sized large enough to do normal
stairs and have an eye-level high enough off the floor to navigate a normal
house. Perhaps like a small dog.   The key is being buildable by
amateurs with limited tools and experience.   The wheeled version goes
first.  The legged version needs 12 reduction drives.   You can see my
interest in reading about your problems with this.

On Sat, Aug 22, 2020 at 9:26 PM Gene Heskett  wrote:

> On Saturday 22 August 2020 19:25:25 Chris Albertson wrote:
>
> > Then go into the CAD software and fill the hex pocket and enlarge the
> > holes to accept the brass inserts or make models threads.
> >
> > At some point to you have to decide that the person who designed this
> > thing only made a first level prototype and more development is
> > required.   I'm following your story and I would have made that
> > determination weeks ago. It is a good fist try, to prove it might work
> > but they break quickly and seem to be very hard to print.My guess
> > is that a few more design iterations are needed.  To make them easier
> > to print and stronger.
> >
> > I think there might be trade-offs reduction ratio and backlash and
> > strength and "printability"
> >
> > I had a professor once who said you can always tell a new or amateur
> > engineer because the stuff he designs only works if you use
> > non-standard high precision parts.  Better designs don't need any of
> > that.  Designing things that work and are printable is hard.  Easier
> > to design stuff in metal with 0.0001 level specs.   This designer was
> > tinking in metal but using plastic.
> >
> Tinking, could be thinking or tinkling. I'm in favor of calling it the
> latter.
>
> "gear ratio" in the case of a harmonic drive, is a huge compromise,
> tradeoff if you will, between the ratio and the amount of flex imparted
> to the flexible member, lower ratios mean taller, wider "teeth" and more
> flex.  Higher ratios need smaller "teeth" and correspondingly less
> flexing. And this one has about the maximum flex the plastic will allow
> without rapid fatigue cracking and failure.  Go for too small and you
> are going to exceed the tolerance of your machine to lay up an accurate
> representation of what the optimum design needs.  And this design may be
> right on the ragged edge. So the exact size of each of the three working
> parts must meet the following criteria:
>
> 1. The max push needs to be far enough out of round that the "teeth" of
> the flexgear spline must, by the shrinkage between the rollers, clear
> the teeth of the internal spline at the mid-point between the rollers,
> otherwise the teeth are forced to snap up and over each other as they're
> forced to pass.  The 3 rollers on each end of the rotating wave plate,
> seem to force tooth contact over a wider section, in turn needing a more
> precise pull-in tension to clear this hop.
>
> 2. The max push needs to drive the teeth to as close to full engagement
> as it can, without trapping the teeth between the rollers and the
> internal gear. Bottoming of the tooth engagement, trapping the flexible
> spline against the internal gear is semi-desirable because that also
> corresponds to the zero backlash condition, but that flexes the cup at
> the base of the spline, forcing a quick breakoff at the bottom of the
> spline.  So there must be a teeny bit of backlash in the plastic
> version.
>
> So you chose, by diddling the printers x and y scales, a size of wave
> plate that allows those 2 conditions.  And the tolerance would appear to
> be about .1mm.  Next you build the flexgear, again by diddling the
> printers scale, such that the built cup, placed over the running wave
> gear, can be seen to be flexing about 1.5 times the height of the teeth.
>
> Then you measure the teeth at the maximum push, and make the internal
> ring, 

Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Saturday 22 August 2020 19:25:25 Chris Albertson wrote:

> Then go into the CAD software and fill the hex pocket and enlarge the
> holes to accept the brass inserts or make models threads.
>
> At some point to you have to decide that the person who designed this
> thing only made a first level prototype and more development is
> required.   I'm following your story and I would have made that
> determination weeks ago. It is a good fist try, to prove it might work
> but they break quickly and seem to be very hard to print.My guess
> is that a few more design iterations are needed.  To make them easier
> to print and stronger.
>
> I think there might be trade-offs reduction ratio and backlash and
> strength and "printability"
>
> I had a professor once who said you can always tell a new or amateur
> engineer because the stuff he designs only works if you use
> non-standard high precision parts.  Better designs don't need any of
> that.  Designing things that work and are printable is hard.  Easier
> to design stuff in metal with 0.0001 level specs.   This designer was
> tinking in metal but using plastic.
>
Tinking, could be thinking or tinkling. I'm in favor of calling it the 
latter.

"gear ratio" in the case of a harmonic drive, is a huge compromise, 
tradeoff if you will, between the ratio and the amount of flex imparted 
to the flexible member, lower ratios mean taller, wider "teeth" and more 
flex.  Higher ratios need smaller "teeth" and correspondingly less 
flexing. And this one has about the maximum flex the plastic will allow 
without rapid fatigue cracking and failure.  Go for too small and you 
are going to exceed the tolerance of your machine to lay up an accurate 
representation of what the optimum design needs.  And this design may be 
right on the ragged edge. So the exact size of each of the three working 
parts must meet the following criteria:

1. The max push needs to be far enough out of round that the "teeth" of 
the flexgear spline must, by the shrinkage between the rollers, clear 
the teeth of the internal spline at the mid-point between the rollers, 
otherwise the teeth are forced to snap up and over each other as they're 
forced to pass.  The 3 rollers on each end of the rotating wave plate, 
seem to force tooth contact over a wider section, in turn needing a more 
precise pull-in tension to clear this hop.

2. The max push needs to drive the teeth to as close to full engagement 
as it can, without trapping the teeth between the rollers and the 
internal gear. Bottoming of the tooth engagement, trapping the flexible 
spline against the internal gear is semi-desirable because that also 
corresponds to the zero backlash condition, but that flexes the cup at 
the base of the spline, forcing a quick breakoff at the bottom of the 
spline.  So there must be a teeny bit of backlash in the plastic 
version.

So you chose, by diddling the printers x and y scales, a size of wave 
plate that allows those 2 conditions.  And the tolerance would appear to 
be about .1mm.  Next you build the flexgear, again by diddling the 
printers scale, such that the built cup, placed over the running wave 
gear, can be seen to be flexing about 1.5 times the height of the teeth.

Then you measure the teeth at the maximum push, and make the internal 
ring, about .15mm bigger to preclude the entrapment between the wave 
gear and the stationary internal gear, and when you then drop that ring 
over the rest of it, you see, on both sides, that they do clear enough 
to do this hop-over, without catching and causing a click.  If that ring 
gear doesn't fit the body's you've already made, then you adjust the 
wave bearing size by say .2mm and start over.  But you can't go very far 
without exceeding the amount of slop in the 4mm bolt holes that put it 
all together. So the size tolerance for each of those 3 parts is 
around .1mm.

In plastic? Keep your rabbits foot VERY handy.  Oh, and the flexgear and 
the output shaft/flange should be a press fit in the 35mm bore of the 
main bearing, so in the case of the flexgear, you can only adjust it by 
about .1mm undersized at the projection into the bore of that main 
bearing where they are bolted, up to what will still be drawn together 
by those 6 bolts without making the bearing too far out of round and 
lumpy turning.

In short, this was NOT a good first project for a new printer that was 
way the hell out of calibration OOTB. I'm not convinced it was a readily 
achieveable project. At $10/hr for my time, I should have bought 3 new 
small ones on ebay and been ahead of this game.

> On Sat, Aug 22, 2020 at 3:42 PM Gene Heskett  
wrote:
> > On Saturday 22 August 2020 16:30:56 Chris Albertson wrote:
> > > The solution is not to use captive hex nuts.
> >
> > Thats what this thing is designed for, if indeed it has pockets for
> > the nuts. The m4's generally have a pocket, but the m3's in the wave
> > bearing carrier are plumb bare.
> >
> > > You can simply print M4
> 

Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Saturday 22 August 2020 19:25:25 Chris Albertson wrote:

> Then go into the CAD software and fill the hex pocket and enlarge the
> holes to accept the brass inserts or make models threads.
>
> At some point to you have to decide that the person who designed this
> thing only made a first level prototype and more development is
> required.   I'm following your story and I would have made that
> determination weeks ago. It is a good fist try, to prove it might work
> but they break quickly and seem to be very hard to print.My guess
> is that a few more design iterations are needed.  To make them easier
> to print and stronger.
>
> I think there might be trade-offs reduction ratio and backlash and
> strength and "printability"
>
> I had a professor once who said you can always tell a new or amateur
> engineer because the stuff he designs only works if you use
> non-standard high precision parts.  Better designs don't need any of
> that.  Designing things that work and are printable is hard.  Easier
> to design stuff in metal with 0.0001 level specs.   This designer was
> tinking in metal but using plastic.

And its died already. But I've not done an autopsy yet. Hungry face takes 
priority. Motor is locked up on something springy. And the mountains are 
making thunderboomers tonight. The important stuff is on a ups though.

> On Sat, Aug 22, 2020 at 3:42 PM Gene Heskett  
wrote:
> > On Saturday 22 August 2020 16:30:56 Chris Albertson wrote:
> > > The solution is not to use captive hex nuts.
> >
> > Thats what this thing is designed for, if indeed it has pockets for
> > the nuts. The m4's generally have a pocket, but the m3's in the wave
> > bearing carrier are plumb bare.
> >
> > > You can simply print M4
> > > size threads inside a hole and screw the cap screw into the
> > > threaded hole.  This works if you don't go through so many
> > > assembly/disassembly cycles.   The best is to use these heat-set
> > > brass thread inserts. Then your screw goes into brass threads.
> > >
> > > In all cases, blue (medium) Locktite works well.
> >
> > And of coarse I have red and green. :(
> >
> > Got the second one running, fairly quietly, but I do need to split
> > it and molycoat the wear areas.  3rd one has a slightly smaller
> > flexgear about 5% built, hopefully it will work with one of the ring
> > gears I have a pile of at various sizes, flow looking good at 100%,
> > even on the brim. Running at 210 and 55 once past the startup layer,
> > I read someplace where strength was enhanced with less cooling under
> > the nozzle, more time to weld itself I guess, so its running that
> > fan at 55%.  And I've resliced with some elephants foot comp (
> > 0.5mm) enabled.  Thats why I had to take the first white one to the
> > lathe and shave that off. That was not a problem with the black, but
> > that stuff is more brittle than the white.  And I'm outta m4x10 ss
> > cap screws and m4 hex nuts, miss-counted badly. Monsterbolts and my
> > banks MC is my friend. :)
> >
> > > amazon.com/Threaded-Heat-Set-Inserts...
> > >  > >tion
> > > /dp/B07BH5X252/ref=sr_1_18?dchild=1=m4+brass+insert+3d+pr
> > >int id=1598128018=industrial=1-18>
> >
> > That would need the source .stl's modified, and I don't know enough
> > about freecad to attempt that. So I'm stuck using the designers
> > fasteners.
> >
> > Thanks Chris.
> >
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > If we desire respect for the law, we must first make the law
> > respectable. - Louis D. Brandeis
> > Genes Web page 
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

Then go into the CAD software and fill the hex pocket and enlarge the holes
to accept the brass inserts or make models threads.

At some point to you have to decide that the person who designed this thing
only made a first level prototype and more development is required.   I'm
following your story and I would have made that determination weeks ago.
 It is a good fist try, to prove it might work but they break quickly and
seem to be very hard to print.My guess is that a few more design
iterations are needed.  To make them easier to print and stronger.

I think there might be trade-offs reduction ratio and backlash and
strength and "printability"

I had a professor once who said you can always tell a new or amateur
engineer because the stuff he designs only works if you use non-standard
high precision parts.  Better designs don't need any of that.  Designing
things that work and are printable is hard.  Easier to design stuff in
metal with 0.0001 level specs.   This designer was tinking in metal but
using plastic.





On Sat, Aug 22, 2020 at 3:42 PM Gene Heskett  wrote:

> On Saturday 22 August 2020 16:30:56 Chris Albertson wrote:
>
> > The solution is not to use captive hex nuts.
>
> Thats what this thing is designed for, if indeed it has pockets for the
> nuts. The m4's generally have a pocket, but the m3's in the wave bearing
> carrier are plumb bare.
>
> > You can simply print M4
> > size threads inside a hole and screw the cap screw into the threaded
> > hole.  This works if you don't go through so many assembly/disassembly
> > cycles.   The best is to use these heat-set brass thread inserts.
> > Then your screw goes into brass threads.
> >
> > In all cases, blue (medium) Locktite works well.
>
> And of coarse I have red and green. :(
>
> Got the second one running, fairly quietly, but I do need to split it and
> molycoat the wear areas.  3rd one has a slightly smaller flexgear about
> 5% built, hopefully it will work with one of the ring gears I have a
> pile of at various sizes, flow looking good at 100%, even on the brim.
> Running at 210 and 55 once past the startup layer, I read someplace
> where strength was enhanced with less cooling under the nozzle, more
> time to weld itself I guess, so its running that fan at 55%.  And I've
> resliced with some elephants foot comp ( 0.5mm) enabled.  Thats why I
> had to take the first white one to the lathe and shave that off. That
> was not a problem with the black, but that stuff is more brittle than
> the white.  And I'm outta m4x10 ss cap screws and m4 hex nuts,
> miss-counted badly. Monsterbolts and my banks MC is my friend. :)
>
> > amazon.com/Threaded-Heat-Set-Inserts...
> >  >/dp/B07BH5X252/ref=sr_1_18?dchild=1=m4+brass+insert+3d+print
> >id=1598128018=industrial=1-18>
>
> That would need the source .stl's modified, and I don't know enough about
> freecad to attempt that. So I'm stuck using the designers fasteners.
>
> Thanks Chris.
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Saturday 22 August 2020 16:30:56 Chris Albertson wrote:

> The solution is not to use captive hex nuts.

Thats what this thing is designed for, if indeed it has pockets for the 
nuts. The m4's generally have a pocket, but the m3's in the wave bearing 
carrier are plumb bare.

> You can simply print M4 
> size threads inside a hole and screw the cap screw into the threaded
> hole.  This works if you don't go through so many assembly/disassembly
> cycles.   The best is to use these heat-set brass thread inserts. 
> Then your screw goes into brass threads.
>
> In all cases, blue (medium) Locktite works well.

And of coarse I have red and green. :(  

Got the second one running, fairly quietly, but I do need to split it and 
molycoat the wear areas.  3rd one has a slightly smaller flexgear about 
5% built, hopefully it will work with one of the ring gears I have a 
pile of at various sizes, flow looking good at 100%, even on the brim. 
Running at 210 and 55 once past the startup layer, I read someplace 
where strength was enhanced with less cooling under the nozzle, more 
time to weld itself I guess, so its running that fan at 55%.  And I've 
resliced with some elephants foot comp ( 0.5mm) enabled.  Thats why I 
had to take the first white one to the lathe and shave that off. That 
was not a problem with the black, but that stuff is more brittle than 
the white.  And I'm outta m4x10 ss cap screws and m4 hex nuts, 
miss-counted badly. Monsterbolts and my banks MC is my friend. :)

> amazon.com/Threaded-Heat-Set-Inserts...
> /dp/B07BH5X252/ref=sr_1_18?dchild=1=m4+brass+insert+3d+print
>id=1598128018=industrial=1-18>

That would need the source .stl's modified, and I don't know enough about 
freecad to attempt that. So I'm stuck using the designers fasteners.

Thanks Chris.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


___
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Emc-users@lists.sourceforge.net
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

The solution is not to use captive hex nuts.   You can simply print M4 size
threads inside a hole and screw the cap screw into the threaded hole.  This
works if you don't go through so many assembly/disassembly cycles.   The
best is to use these heat-set brass thread inserts.  Then your screw goes
into brass threads.

In all cases, blue (medium) Locktite works well.

amazon.com/Threaded-Heat-Set-Inserts...


On Sat, Aug 22, 2020 at 12:39 PM Gene Heskett  wrote:

> On Friday 21 August 2020 18:32:11 Gene Heskett wrote:
>
> Thread continued, sorta.
>
> Another problem I am noting, and I'm curious if its been noted by others,
> and any possible fixes for it found, "cold flow".
>
> Several places in this assembly are held by m3 cap screws, and while the
> nuts should be held, there's no lock washers, nor room for them.  So you
> tighten them 1/4 turn from broke.  But just sitting on the table
> overnight, you can remove the nuts with your fingers the next morning.
> The plastic has relaxed due to cold flow, releasing the tension on the
> nut that WAS holding it tight 10 hours ago.
>
> This gorilla stick glue can be used to keep the nut from vibrating plumb
> off the end of the bolt and mucking up the works, but its still loose.
> Is that the best we can do?
>
> Use with the new micro-swiss hotend and feed conversion is still young,
> but since putting a narrow strip of teflon tape wrapped about 2 turns
> into the nozzles threads, and carefully trimming it so no stray tape
> could block the nozzle, I've had no repeats of that problem.  And I'm
> getting close to zeroed in on the feed rate, I only have it advanced to
> 110% and the part being built is looking great.
>
> Thanks all for any suggestions about cold flow problems.
>
>
> Yes, that thumping sound is what you think it is. ;-)
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Friday 21 August 2020 18:32:11 Gene Heskett wrote:

Thread continued, sorta.

Another problem I am noting, and I'm curious if its been noted by others, 
and any possible fixes for it found, "cold flow".

Several places in this assembly are held by m3 cap screws, and while the 
nuts should be held, there's no lock washers, nor room for them.  So you 
tighten them 1/4 turn from broke.  But just sitting on the table 
overnight, you can remove the nuts with your fingers the next morning. 
The plastic has relaxed due to cold flow, releasing the tension on the 
nut that WAS holding it tight 10 hours ago.

This gorilla stick glue can be used to keep the nut from vibrating plumb 
off the end of the bolt and mucking up the works, but its still loose. 
Is that the best we can do?

Use with the new micro-swiss hotend and feed conversion is still young, 
but since putting a narrow strip of teflon tape wrapped about 2 turns 
into the nozzles threads, and carefully trimming it so no stray tape 
could block the nozzle, I've had no repeats of that problem.  And I'm 
getting close to zeroed in on the feed rate, I only have it advanced to 
110% and the part being built is looking great.

Thanks all for any suggestions about cold flow problems.


Yes, that thumping sound is what you think it is. ;-)

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Friday 21 August 2020 15:35:26 Gene Heskett wrote:

> On Friday 21 August 2020 12:45:11 Chris Albertson wrote:

> Checking just now, its up to a 
> step over a mm up, the brim looks pretty gossamer, but the higher
> stuff doesn't look like its starving, just on a diet. Might have a
> usable part. Later, its looking like a good part about 1/2 done.
>
> It only took a 5 minute run to break the flexgear I'd made out of
> white PLA with the old hotend, and the next one I made about .1%
> smaller, had enough elephants foot I'll never make it work.

I got that one fixed, took it to the lathe. Sharpened up a cutoff blade 
and gave it a cheap shave.

Now I'm building the bigger piece of the wave gear bearing carrier, and 
feel I finally have enough plastic. st/mm is now 250, and flow is at 
150% and its not looking too shabby. I should flag the fiber, and check 
the delivery for a 100mm push at some point, but don't know how without 
removing the nozzle, and convincing Merlin to move it cold, which it 
will not do.  There's now about 1.5" between the fiber drive and the 
nozzle. 3.5 cm maybe.

The mail has come,

> And the tpu still hasn't appeared. Shoulda been here on the 17th.
> Story of life in rural WV, hurry up so you can wait longer. :(
>
> Thanks Chris.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Friday 21 August 2020 12:45:11 Chris Albertson wrote:

> You remind my of something I always do and it would help with you
> adhesion problem and allows parts to be removed with less effort.   I
> always place a fillet around the edge of the part. So whatever
> surface is touching the build plate should have a fillet, even if it
> is only 0.5mm radius it helps to allow a putty knife to get under the
> part. You have to add this using the CAD software.   Yes, Cura can
> shrink the size of the first layer but it is not the same as a fillet
> and you may have to do both to get a nice round edge.

I sharpen my putty knife on a 12,000 grit rouge wheel, wet if I'm not too 
lazy to carry it a gallon of water for the water dribbler. It gets under 
a gnat w/o shaving a hole in his shoe soles. ;)
>
But last night, after installing the micro-swiss hot end and extruder 
drive combo, their recommendation of an extruder drive of about 130 
step/mm left it without near enough extrusion, and I was pumping it up 
5% at a time with tune menu's flow setting, and that almost made it 
work, but I was still getting dashes with a tail, not a steady line 
laydown. The motion of the extruder drive seem quite excessive as it was 
makeing a small part, but I needed to check my eyelids for leaks, so I 
turned down the flow feed about 25% and took a nap.  When I came to, 2 
hours later the part was following the head around and both were buried 
in a golf ball sized gob of steel wool, only plastic. The bottom of the 
hot block was encased in plastic, and the sock was expanded.  All 
evidence pointed to plastic comeing down thru the nozzles threads!

I gave up and went back to bed,  This morning I rustle up a 7mm socket, 
heat the extruder up to about 240 and removed the nozzle. Wrapped a 
couple layers of plumbers teflon tape around the threads, started it 
about half a turn and warmed the hot block back up to 240 and tightened 
it 1/8 turn from stripped.  Noted the fan was stamped as a 24 volt.  So 
now I know which fans to buy. Restored their recommended settings for 
steps/mm, re-leveled the plate and I've been doing 1 or 2 layers at a 
time, looking for the right feed and heat to make it stick, and looking 
at spider webs blowning in the wind until just now, its laid down a brim 
that was stuck when I got up to do something about my coffee cup whose 
bottom was turning into the Sahara, and to check for incoming mail. 
Checking just now, its up to a step over a mm up, the brim looks pretty 
gossamer, but the higher stuff doesn't look like its starving, just on a 
diet. Might have a usable part. Later, its looking like a good part 
about 1/2 done.

It only took a 5 minute run to break the flexgear I'd made out of white 
PLA with the old hotend, and the next one I made about .1% smaller, had 
enough elephants foot I'll never make it work.

And the tpu still hasn't appeared. Shoulda been here on the 17th.
Story of life in rural WV, hurry up so you can wait longer. :(

Thanks Chris.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

You remind my of something I always do and it would help with you
adhesion problem and allows parts to be removed with less effort.   I
always place a fillet around the edge of the part. So whatever
surface is touching the build plate should have a fillet, even if it is
only 0.5mm radius it helps to allow a putty knife to get under the part.
  You have to add this using the CAD software.   Ues, Cura can shrink the
size of the first layer but it is not the same as a fillet and you may have
to do both to get a nice round edge.

On Thu, Aug 20, 2020 at 10:23 PM Gene Heskett  wrote:

> On Thursday 20 August 2020 20:37:45 Gregg Eshelman via Emc-users wrote:
>
> > Blue painter's tape on the glass, edges butted together. Wipe down
> > gently with rubbing alcohol to remove the wax that makes it possible
> > to unroll the tape.
>
> I'll have to locate a fresh supply of that stuff, whatever I may have
> squirreled away is years old.
>
> The micro-swiss hot end came in today and got installed, and following
> their directions I'm back to makeing plastic starved prints.  Still
> calibrating it IOW.  It also puts the home 0,0 point clear off the glass
> and I'm still trying to figure out how to move that.  The prime the
> extruder run down the left edge is missing the glass about 2mm's.
>
> Another problem has stuck its hand up and waved at me.  Using the white
> stuff, I'm getting elephants foot on the bottoms.  I think there a comp
> for that in cura, but I've not re-found it yet.
>
> Thanks Greg.
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
> ___
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>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Thursday 20 August 2020 20:37:45 Gregg Eshelman via Emc-users wrote:

> Blue painter's tape on the glass, edges butted together. Wipe down
> gently with rubbing alcohol to remove the wax that makes it possible
> to unroll the tape.

I'll have to locate a fresh supply of that stuff, whatever I may have 
squirreled away is years old.

The micro-swiss hot end came in today and got installed, and following 
their directions I'm back to makeing plastic starved prints.  Still 
calibrating it IOW.  It also puts the home 0,0 point clear off the glass 
and I'm still trying to figure out how to move that.  The prime the 
extruder run down the left edge is missing the glass about 2mm's.

Another problem has stuck its hand up and waved at me.  Using the white 
stuff, I'm getting elephants foot on the bottoms.  I think there a comp 
for that in cura, but I've not re-found it yet.

Thanks Greg.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gregg Eshelman via Emc-users]

Blue painter's tape on the glass, edges butted together. Wipe down gently with 
rubbing alcohol to remove the wax that makes it possible to unroll the tape.

On Thursday, August 20, 2020, 8:07:12 AM MDT, Gene Heskett 
 wrote:  
Thanks for any hints on how to reliably control the adhesion with white 
PLA.  Its sticking way too good.

Cheers, Gene Heskett  
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Thursday 20 August 2020 10:03:56 Gene Heskett wrote:
>
> I'm still trying to control adhesion, I am damaging the glass
> chiseling my prints loose.  I do have 2 of these drive things running
> now, and I was going to try a 40C bed at 190C for the last flexgear,
> but that still blocked the flow, and it wasn't till I warmed up the
> extruder to 210 that the flow motor stopped complaining.
>
> Thanks for any hints on how to reliably control the adhesion with
> white PLA.  Its sticking way too good.

And the 2nd one died in about an hour, broken flexgear, and it was still 
2 red ones too big for the main bearing, so another .2 reduction in 
scale is building now, broken this time at the junction of wall top and 
spline, possibly by an oversized bearing carrier, pressing the splines 
tightly for no backlash, concentrating the flexure at the bottom of the 
splines. Perhaps I'll have to tolerate a red hair of backlash?

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Thursday 20 August 2020 00:54:07 Bruce Layne wrote:

> I'm starting to use larger quantities of filament in a small but
> growing 3D print farm.  I'd love to find someplace where I could buy
> 10-100 kg of filament per order and be assured of good quality and
> good pricing, but I've been surprised that my initial investigations
> have been mostly fruitless.  Maybe my search-fu is weak, but it looks
> like online sources aren't much better than Amazon.
>
> I did stumble across MakeShaper.com.  I recently placed an order for
> two 2.25kg reels of ABS filament.  With the discount code from their
> website and free shipping, it was 1.62 cents per gram, probably the
> least expensive filament I've purchased, and it prints like a dream. 
> It's the only filament I've ever used that doesn't dribble when the
> nozzle is preheated, but it prints very well without stringing or
> blobs.  It doesn't have the styrene smell of other ABS filament when
> printing.  The filament feeds reliably from the spool and the diameter
> in both reels is always 1.74mm or 1.75mm - much higher tolerance than
> other brands.  The 84th part just finished of a 100 part order.  In 30
> minutes, the part will contract and separate from the glass plate. 
> I'll lift it from the bed effortlessly, apply a few milliliters of
> glue juice (10 grams of Elmer's XTreme glue stick dissolved in 500 ml
> of distilled water), I'll spread the glue juice on the glass bed with
> a nylon bristle brush and press Print Another Copy.  Easy peasey. 
> Having good filament is important to reliable and trouble free 3D
> printing.  I'm sure bad filament is the source of a lot of frustration
> and failed prints.

And that consideration may be part of why no one is stocking "in depth", 
because this stuff absorbs moisture. O of the things I noted when I 
opened up a roll of white PLA was that the other stuff comes vacuum 
sealed in a heavy poly bag with a pill bottle sized bag of dessicant, 
this white had a big bag stuffed into the reel core with about 4 or 6x 
the silica gel the cheap stuff comes with.

> If anyone has a good source of quality 3D printing filament at a good
> price, particularly TPU, I'd love to hear your suggestion.

I'm still trying to control adhesion, I am damaging the glass chiseling 
my prints loose.  I do have 2 of these drive things running now, and I 
was going to try a 40C bed at 190C for the last flexgear, but that still 
blocked the flow, and it wasn't till I warmed up the extruder to 210 
that the flow motor stopped complaining.

Thanks for any hints on how to reliably control the adhesion with white 
PLA.  Its sticking way too good.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Bruce Layne]

I'm starting to use larger quantities of filament in a small but growing
3D print farm.  I'd love to find someplace where I could buy 10-100 kg
of filament per order and be assured of good quality and good pricing,
but I've been surprised that my initial investigations have been mostly
fruitless.  Maybe my search-fu is weak, but it looks like online sources
aren't much better than Amazon.

I did stumble across MakeShaper.com.  I recently placed an order for two
2.25kg reels of ABS filament.  With the discount code from their website
and free shipping, it was 1.62 cents per gram, probably the least
expensive filament I've purchased, and it prints like a dream.  It's the
only filament I've ever used that doesn't dribble when the nozzle is
preheated, but it prints very well without stringing or blobs.  It
doesn't have the styrene smell of other ABS filament when printing.  The
filament feeds reliably from the spool and the diameter in both reels is
always 1.74mm or 1.75mm - much higher tolerance than other brands.  The
84th part just finished of a 100 part order.  In 30 minutes, the part
will contract and separate from the glass plate.  I'll lift it from the
bed effortlessly, apply a few milliliters of glue juice (10 grams of
Elmer's XTreme glue stick dissolved in 500 ml of distilled water), I'll
spread the glue juice on the glass bed with a nylon bristle brush and
press Print Another Copy.  Easy peasey.  Having good filament is
important to reliable and trouble free 3D printing.  I'm sure bad
filament is the source of a lot of frustration and failed prints.

If anyone has a good source of quality 3D printing filament at a good
price, particularly TPU, I'd love to hear your suggestion.





On 8/19/20 11:34 PM, James Isaac wrote:
>
>> The white pla is not the same stuff as the black, by a hell of a long row
> of apple trees.  Where the black is a brittle as can be cold, the white
> is much more forgiving,  . . .
>
> Back in about 1977, I got told the black plastic was the first that was 
> recycled.
> The people doing the recycling needed a consistent colour in their product,
> and hid the recycling by changing the colour to black.
> The quantity of additives needed to mask the multiple colours of the source 
> plastic changed the properties of the plastic at the same time.
>
> Sounds as though the same thing is happening today.
>
> James Isaac.
>
>
> 
> From: Gene Heskett 
> Sent: August 19, 2020 10:47 PM
> To: emc-users@lists.sourceforge.net 
> Subject: Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse
>
> On Wednesday 19 August 2020 19:17:08 Gene Heskett wrote:
>
> Well, I'm back, hat in hand.
>
> The white pla is not the same stuff as the black, by a hell of a long row
> of apple trees.  Where the black is a brittle as can be cold, the white
> is much more forgiving, AND it sticks to the glass about 1000 times
> better, I just interrupted the job because I moved the glass trying to
> get the priming . . .
>
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[James Isaac]

> The white pla is not the same stuff as the black, by a hell of a long row
of apple trees.  Where the black is a brittle as can be cold, the white
is much more forgiving,  . . .

Back in about 1977, I got told the black plastic was the first that was 
recycled.
The people doing the recycling needed a consistent colour in their product,
and hid the recycling by changing the colour to black.
The quantity of additives needed to mask the multiple colours of the source 
plastic changed the properties of the plastic at the same time.

Sounds as though the same thing is happening today.

James Isaac.



From: Gene Heskett 
Sent: August 19, 2020 10:47 PM
To: emc-users@lists.sourceforge.net 
Subject: Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

On Wednesday 19 August 2020 19:17:08 Gene Heskett wrote:

Well, I'm back, hat in hand.

The white pla is not the same stuff as the black, by a hell of a long row
of apple trees.  Where the black is a brittle as can be cold, the white
is much more forgiving, AND it sticks to the glass about 1000 times
better, I just interrupted the job because I moved the glass trying to
get the priming . . .

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gregg Eshelman via Emc-users]

Could build a crossed gantry printer 
https://hackaday.com/2020/08/19/re-imagining-the-crossed-gantry-3d-printer/
Toolchanging between plastic extruder and milling tool for high surface 
precision with FDM printing 
https://hackaday.com/2020/08/18/e3d-teaches-additive-machines-how-to-subtract/
Using a sharpie marker to make support removal much easier 
https://hackaday.com/2020/05/27/improving-3d-printed-supports-with-a-marker/This
 person automated it but pause commands inserted in the right place would make 
it possible to scribble on top of the support then resume.






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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Wednesday 19 August 2020 19:17:08 Gene Heskett wrote:

Well, I'm back, hat in hand.

The white pla is not the same stuff as the black, by a hell of a long row 
of apple trees.  Where the black is a brittle as can be cold, the white 
is much more forgiving, AND it sticks to the glass about 1000 times 
better, I just interrupted the job because I moved the glass trying to 
get the priming strip off, and it was stuck tight enough my pulling it 
moved the glass despite clothes pins front and rear, and it took cold 
running water and three trips to the edge burnisher with the putty knife 
and half an hour to get the last of the first .4mm back off the glass. 
So obviously I can drop the bed temp about 10C from my usual startup. 
And set the nozzle temp down a ways too.

Right now the glass is clean clean, barkeeper's friend clean and well 
rinsed.  What would you guys do to reduce adhesion to manageable levels?

An extra obvious layer of this purple stick school glue?  Or ???

So far with that stuff, more is less and vice-versa.  Bare glass I get 
the impression would be a forever stuck disaster.

Thanks.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

I was not suggesting a cycloidal drive for your application.   You need
something that can't be back driven and harmonic is best.   My comment was
that soon you will know more than the designer of this thing.   I did that
with printed drone chassis.   I made a bunch then broke them and made more.
   Plastic works well for prototypes and learning but in the end you can't
beat metal for things like gears and bearings.

For my toy car project, I started with printing the ball bearing units as a
disk with a hole in it.  They work for about 5 minutes.  Nest I made them
from mild steel and they work well.   In the final build, I buy real deep
groove bearings.  Same with my printed timing belts.  They work for
hours.   Then I deside to change something.  When the design a fixed I'll
buy real belts, real bearings and make the motor mounts with aluminum.

In my case, I need back drivable reduction systems that are ultra
compact for robots.  I don't need a huge strength because a large impact
spins the motor backward and with luck we recover that energy back to the
battery.

If you design from the start around cheap bearing you can save a pile of
cash.  608ZZ type can be bought for 14 cents each from China
ebay.com/itm/100PCS-608-ZZ-Skateboard-Bearings-Double-Shielded-8x22x7


Same for smaller ones
https://www.ebay.com/itm/100pcs-623ZZ-Ball-Bearing-3x10x4mm


The trick is to find the good deals on bearings and screws FIRST, then do
the design.

On Wed, Aug 19, 2020 at 4:19 PM Gene Heskett  wrote:

> On Wednesday 19 August 2020 17:52:39 Chris Albertson wrote:
>
> > I suspect that in the end you will need to design your own reduction
> > drive from a clean sheet of paper using what you learn from building
> > this.  I think I'd make the gear teeth larger so that small printing
> > errors don't matter.
> >
> That also reduces the gear ratio. But I don't have that math handy other
> than to note I counted splines and decided it was a 30/1, but I am
> observing more than that I think.
>
> I've made the second new flexgear at the same scale is the other, and
> according to my measurements to get full mesh, I need a wave bearing of
> 74.23mm so since I've lost the scale references for that part, but have
> made several bigger, too big in fact, I switched PLA spools for some
> white that I can write notes on, and reset the printer for a scale of
> 80.00 per mm, a std I can do math from, and its made the cap, with
> prelim measurements indicating it will be about 74.10mm so I'm already
> pretty close.  The carrier I had in it, which is a hair too small, is
> 73.51, and a caliper stretching it to fit 100% at the apex's says I need
> 74.23.  I should be able to assemble and test this one around 21:00.
> That 74.23 is a 2 point measurement, but this carrier has 6 bearings, 3
> on each end. With the other 4 touching, 74.10 might be enough.
>
> I'm trying to conjure up a scheme to mount a good size rotron fan  on the
> top frame bar to come on and blow down on the plate to speed up the
> glass cooling at the end of the job.  The cooldown is a significant part
> of the production time for smaller parts like the bearing carrier
>
> > My plan with my plastic printed milling machine parts is to do a
> > boot-strap where I use the plastic machine to make metal parts.   You
> > might have to do that same, use the plastic reduction units to make a
> > better one in metal.
> >
> > I'm wanting to try to make one of there using rubber timing belts as
> > gear teeth.   There are some belt profiles that mesh with themselves
>
> Not without a cyclic velocity 

Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Wednesday 19 August 2020 17:52:39 Chris Albertson wrote:

> I suspect that in the end you will need to design your own reduction
> drive from a clean sheet of paper using what you learn from building
> this.  I think I'd make the gear teeth larger so that small printing
> errors don't matter.
>
That also reduces the gear ratio. But I don't have that math handy other 
than to note I counted splines and decided it was a 30/1, but I am 
observing more than that I think.

I've made the second new flexgear at the same scale is the other, and 
according to my measurements to get full mesh, I need a wave bearing of 
74.23mm so since I've lost the scale references for that part, but have 
made several bigger, too big in fact, I switched PLA spools for some 
white that I can write notes on, and reset the printer for a scale of 
80.00 per mm, a std I can do math from, and its made the cap, with 
prelim measurements indicating it will be about 74.10mm so I'm already 
pretty close.  The carrier I had in it, which is a hair too small, is 
73.51, and a caliper stretching it to fit 100% at the apex's says I need 
74.23.  I should be able to assemble and test this one around 21:00.
That 74.23 is a 2 point measurement, but this carrier has 6 bearings, 3 
on each end. With the other 4 touching, 74.10 might be enough.

I'm trying to conjure up a scheme to mount a good size rotron fan  on the 
top frame bar to come on and blow down on the plate to speed up the 
glass cooling at the end of the job.  The cooldown is a significant part 
of the production time for smaller parts like the bearing carrier 

> My plan with my plastic printed milling machine parts is to do a
> boot-strap where I use the plastic machine to make metal parts.   You
> might have to do that same, use the plastic reduction units to make a
> better one in metal.
>
> I'm wanting to try to make one of there using rubber timing belts as
> gear teeth.   There are some belt profiles that mesh with themselves

Not without a cyclic velocity variation to deal with.  One of the secrets 
to the splined design is very constant velocity because the "teeth" are 
all carrying load as they slide down the mateing side ramps of the saw 
tooth spline format.  Thats primarily the reason I chose this project.  
Cycloid's share that but with all those bearings, bearing costs will eat 
your lunch.

Thanks Chris.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

I suspect that in the end you will need to design your own reduction drive
from a clean sheet of paper using what you learn from building this.  I
think I'd make the gear teeth larger so that small printing errors don't
matter.

My plan with my plastic printed milling machine parts is to do a boot-strap
where I use the plastic machine to make metal parts.   You might have to do
that same, use the plastic reduction units to make a better one in metal.

I'm wanting to try to make one of there using rubber timing belts as gear
teeth.   There are some belt profiles that mesh with themselves

On Wed, Aug 19, 2020 at 11:37 AM Gene Heskett  wrote:

> On Wednesday 19 August 2020 12:09:05 Gene Heskett wrote:
>
> > On Wednesday 19 August 2020 10:25:14 Greg Bernard wrote:
> > > Most hardware stores carry silicone grease for o-rings in the
> > > plumbing section. I'd be willing to bet it would work just fine for
> > > your purpose.
> >
> > Thats similar to DC-4, and I have some of that but its 60 yo.
> > "Borrowed" it while building titan ones up in SD in '60. But as a
> > lubricant, not to good, -0 surface tension. So I didn't think of it.
> >
> > Its running on a thin film of Lymans Super Moly barrel grease, seems
> > happy but its young yet. Running nicely at noon yet, at about 15 rpm
> > out, sounds like maybe 1000 revs in. Can't stop it by hand. More
> > making.
> >
> > Looked at printers, thought I'd found one in the Saphire, till I read
> > the reviews, zero support, crappily made, 9 reviews, all complaining.
> > Thumbs down.
> >
> But the cyclic noise seemed to be getting worse, like the tips of the
> splines were starting to drag again. So I took it apart, and found
> something else that bothers me, in addition to the motor mount screw
> back out an making a slight mark on the carrier, all 3 of the bearing
> carriers I have printed are .2mm non symmetrical, as in one center
> bearing runs .2mm farther from the shaft than the other. This is causing
> the whole cup to wobble and it can be seen and felt in the output
> flange.  Greased the inside of the cup. Went to garage and got a dial
> and found that on an inch dial, only around a thou difference. Put a
> bigger stator ring in it about .3mm bigger, just enough to make the
> bolts drag going back in. Back to running till? At max divisor and about
> 250 kilohertz steps. This gave it a just detectable backlash.  Way more
> than that in the BS-1's worm at best setting. Which may be where this
> one is going if I don't destroy it first  And I'm trying to find the
> weakest link here.  Another thing of note, at .5 amps a coil, the
> current mapping of these tb6560's sucks dead toads thru soda straws, the
> microstepping is nowhere linear. And makes the iron complain
> vocipherously.
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
> ___
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> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Wednesday 19 August 2020 12:09:05 Gene Heskett wrote:

> On Wednesday 19 August 2020 10:25:14 Greg Bernard wrote:
> > Most hardware stores carry silicone grease for o-rings in the
> > plumbing section. I'd be willing to bet it would work just fine for
> > your purpose.
>
> Thats similar to DC-4, and I have some of that but its 60 yo.
> "Borrowed" it while building titan ones up in SD in '60. But as a
> lubricant, not to good, -0 surface tension. So I didn't think of it.
>
> Its running on a thin film of Lymans Super Moly barrel grease, seems
> happy but its young yet. Running nicely at noon yet, at about 15 rpm
> out, sounds like maybe 1000 revs in. Can't stop it by hand. More
> making.
>
> Looked at printers, thought I'd found one in the Saphire, till I read
> the reviews, zero support, crappily made, 9 reviews, all complaining.
> Thumbs down.
>
But the cyclic noise seemed to be getting worse, like the tips of the 
splines were starting to drag again. So I took it apart, and found 
something else that bothers me, in addition to the motor mount screw 
back out an making a slight mark on the carrier, all 3 of the bearing 
carriers I have printed are .2mm non symmetrical, as in one center 
bearing runs .2mm farther from the shaft than the other. This is causing 
the whole cup to wobble and it can be seen and felt in the output 
flange.  Greased the inside of the cup. Went to garage and got a dial 
and found that on an inch dial, only around a thou difference. Put a 
bigger stator ring in it about .3mm bigger, just enough to make the 
bolts drag going back in. Back to running till? At max divisor and about 
250 kilohertz steps. This gave it a just detectable backlash.  Way more 
than that in the BS-1's worm at best setting. Which may be where this 
one is going if I don't destroy it first  And I'm trying to find the 
weakest link here.  Another thing of note, at .5 amps a coil, the 
current mapping of these tb6560's sucks dead toads thru soda straws, the 
microstepping is nowhere linear. And makes the iron complain 
vocipherously.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Wednesday 19 August 2020 10:25:14 Greg Bernard wrote:

> Most hardware stores carry silicone grease for o-rings in the plumbing
> section. I'd be willing to bet it would work just fine for your
> purpose.
>
Thats similar to DC-4, and I have some of that but its 60 yo. "Borrowed" 
it while building titan ones up in SD in '60. But as a lubricant, not to 
good, -0 surface tension. So I didn't think of it.

Its running on a thin film of Lymans Super Moly barrel grease, seems 
happy but its young yet. Running nicely at noon yet, at about 15 rpm 
out, sounds like maybe 1000 revs in. Can't stop it by hand. More making.

Looked at printers, thought I'd found one in the Saphire, till I read the 
reviews, zero support, crappily made, 9 reviews, all complaining. Thumbs 
down.

> On Wed, Aug 19, 2020, 5:02 AM Gene Heskett  
wrote:
> > On Wednesday 19 August 2020 00:19:40 Gene Heskett wrote:
> > > On Tuesday 18 August 2020 20:30:45 Gene Heskett wrote:
> > > > On Tuesday 18 August 2020 18:50:22 Frank Tkalcevic wrote:
> > > > > > the middle of a now thicker and nuch denser 6 wall build. 
> > > > > > cura settings are for 6 line walls, 15 ipm and 30 ipm.
> > > > >
> > > > > 6 line walls/perimeters is a large number.   My default
> > > > > setting is 2. Less perimeters also prints a lot faster.  If
> > > > > the part is weak, you can always increase it later, but it
> > > > > sounds like you are still having issue with the extrusion flow
> > > > > rate.
> > > >
> > > > The 2 I broke already were made before I calibrated it and found
> > > > it set for about 18mm of pla for a 100mm move. At 6, its buckets
> > > > sturdier, but the bearing bottom was 35.5mm and I killed a
> > > > bearing putting it together.  So I've scaled it down a wee bit
> > > > and will make another for the 3rd one if this one fits better.
> > >
> > > I picked the smallest bearing carrier I had assembled, stuck on
> > > that motor, and picked the smallest internal spline ring. Bolted
> > > it all up. Its been running at about 400 rpm input, and a turn
> > > every 4 seconds for output for longer than the other 2 together.
> > > But its crackling and stalling, too it apart, flexgear is good,
> > > but I think it doesn't have quite enough hop over clearance.  The
> > > next on on the printer should be a few thou smaller. This will
> > > also get me into it far enough to refresh that lumpy bearing.
> > >
> > > But I need some sleep while the next one is finishing.
> >
> > It has, it fits perfectly in a new main bearing, and the smaller
> > wave carrier I used before is in it, along with the stator ring. Its
> > running quieter at about 6 rpm.  Dry, but I was looking at my
> > cooking oil, thaws at 75F coconut and wondering.  Now they are
> > telling me the si stuff I ordered, won't be here before Nov 7th.  I
> > think that belongs in the WTF category... Another one started, this
> > ones running and I'm going back to bed.
> >
> > > > Thanks Frank.
> > > >
> > > > Cheers, Gene Heskett
> > >
> > > Cheers, Gene Heskett
> >
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > If we desire respect for the law, we must first make the law
> > respectable. - Louis D. Brandeis
> > Genes Web page 
> >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
> ___
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Wednesday 19 August 2020 01:53:13 Gregg Eshelman via Emc-users wrote:

> More perimeters = more strength in FDM printing. For rigid plastics
> like PLA that also increases stiffness. Several years ago, Benelli was
> designing a new auto loading shotgun and they had a problem with part
> of the bolt breaking. They made it thicker serveral times, they tried
> different metals, they tried different hardening treatments but the
> part would always eventually break. Then they applied some better
> analysis techniques to find how the part was trying to flex when the
> gun was fired and made a bolt with that part thinner than the first
> one which broke. Allowing the part to flex stopped it from breaking,
> and the lighter weight increased the cycling speed to the point where
> some trick shooters were able to break longstanding records like how
> many clay targets they could hand toss into the air and shoot before
> any hit the ground. So rather than tying to make the part ever
> stronger, and thus less flexible, you need to see what can be altered
> in the 3D model to make the area where it breaks more flexible.
>
The 6 layer wall part is still running.  The problem is the concentration 
of the flex at the base of the wall.  There is a filet at the junction 
of wall and disk, and it was breaking at the exact top of the filet. 
Going from 3 to 6 on that wall thickness did increase the stiffness 
some, but getting the wave bearing the right size to remove the roughly 
2x needed flex seems to have been the fix.

Makeing all parts at the same printer scale gets a flexure so excess 
theres 3mm of air between the spline teeth midway between the bearings 
and with that much flex its bound to break in 5 minutes or less.

The first one I assembled yesterday had a fraction of a mm too big a butt 
end and I beat the bearing up getting it inserted, made another by 
changing the scale down from a calculated 80.79 down by .14 to 80.65, 
(In terms of scale per mm in merlin) which also increased the wave about 
5 thou, enough that I am not hearing a crackling sound as the splines 
hop over each other.  But that was the only internal spline I had that 
still fits in the bodies which were made first after calibrating the 
extruder feed. So I have another flexgear in process and will make a 3rd 
one that size.  Then I'll make another bearing carrier and adjust it to 
be the same as the one thats working. Then measure the internal spline 
and adjust to make 2 more that size which does fit the bodies and motor 
caps both of which have a surrounding flange to hide the spline when 
they come together at assembly. And that should do it.

And I am tempted drill for a lube hole thru the spline face to allow some 
lube to be inserted with a hypo needle or such. I just need to find a 
plastic compatible lube on this side of the big pond.  Everybody has it, 
but when you order it, it has to come from some goat herders shack in 
Ulan Bator, by donkey cart. In the meantime, I am tempted to try some 
barrel grease I have that made for molycoating rifle barrel bores, its 
about 95% molysulfide, it should stay where I put it with a q-tip.  What 
it will do to the PLA is TBD.

I believe I am fighting with a variation of the cartographers copyright 
scheme.  An error was detectable in a copyright violation copy by 
looking for a town that only the original map drawer knows is fake.  And 
this error, purposely designed to fail, was this guys copyright 
detector.  Its a very old ploy, and holds up in court 100% of the time.

Neither the tpu, nor the micro-swiss hot end kit appeared yesterday. My 
personal curse for living in a technological vacuum. Long distance 
shopping.

So I took it apart and smeared some of that on the tips of the teeth, and 
found another potential wear site. Where the bearings are rolling on the 
inside face is worn noticeably smoother. The bearings are rolling 
smoothly but I am wondering if I should have colored that area with some 
of that moly grease now just to slow that wear. That did help with the 
torque multiply, as it cannor now be stalled by hand despite running at 
this driver lowest, not much heating, current.

These drivers respond instantly to the changes in the dip switch 
settings, so I contemplating the removal of the dip switch to gain 
access to the pads for current control for linuxcnc to put max current 
to the motor if its running, idling back to minimum current for holding 
when stopped.

Can I get an only when moving that axis signal out of motion? And do it 
without losing a step? I have a oneshot in mind, trigger on leading 
edge, but send the step so its done on the falling edge, giving a couple 
u-secs for the current to rise?  Sneaky but it might work.  Our goal is 
to make sneaky work reliably isn't it?  Or should I junk these and get a 
tb6600 that incorporates that. Except it doesn't.

> On Tuesday, August 18, 2020, 5:23:58 PM MDT, Frank Tkalcevic 
 wrote:
>  > the middle of a now 

Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Greg Bernard]

Most hardware stores carry silicone grease for o-rings in the plumbing
section. I'd be willing to bet it would work just fine for your purpose.

On Wed, Aug 19, 2020, 5:02 AM Gene Heskett  wrote:

> On Wednesday 19 August 2020 00:19:40 Gene Heskett wrote:
>
> > On Tuesday 18 August 2020 20:30:45 Gene Heskett wrote:
> > > On Tuesday 18 August 2020 18:50:22 Frank Tkalcevic wrote:
> > > > > the middle of a now thicker and nuch denser 6 wall build.  cura
> > > > > settings are for 6 line walls, 15 ipm and 30 ipm.
> > > >
> > > > 6 line walls/perimeters is a large number.   My default setting is
> > > > 2. Less perimeters also prints a lot faster.  If the part is weak,
> > > > you can always increase it later, but it sounds like you are still
> > > > having issue with the extrusion flow rate.
> > >
> > > The 2 I broke already were made before I calibrated it and found it
> > > set for about 18mm of pla for a 100mm move. At 6, its buckets
> > > sturdier, but the bearing bottom was 35.5mm and I killed a bearing
> > > putting it together.  So I've scaled it down a wee bit and will make
> > > another for the 3rd one if this one fits better.
> >
> > I picked the smallest bearing carrier I had assembled, stuck on that
> > motor, and picked the smallest internal spline ring. Bolted it all up.
> > Its been running at about 400 rpm input, and a turn every 4 seconds
> > for output for longer than the other 2 together. But its crackling and
> > stalling, too it apart, flexgear is good, but I think it doesn't have
> > quite enough hop over clearance.  The next on on the printer should be
> > a few thou smaller. This will also get me into it far enough to
> > refresh that lumpy bearing.
> >
> > But I need some sleep while the next one is finishing.
>
> It has, it fits perfectly in a new main bearing, and the smaller wave
> carrier I used before is in it, along with the stator ring. Its running
> quieter at about 6 rpm.  Dry, but I was looking at my cooking oil, thaws
> at 75F coconut and wondering.  Now they are telling me the si stuff I
> ordered, won't be here before Nov 7th.  I think that belongs in the WTF
> category... Another one started, this ones running and I'm going back to
> bed.
>
> > > Thanks Frank.
> > >
> > > Cheers, Gene Heskett
> >
> > Cheers, Gene Heskett
>
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Wednesday 19 August 2020 00:19:40 Gene Heskett wrote:

> On Tuesday 18 August 2020 20:30:45 Gene Heskett wrote:
> > On Tuesday 18 August 2020 18:50:22 Frank Tkalcevic wrote:
> > > > the middle of a now thicker and nuch denser 6 wall build.  cura
> > > > settings are for 6 line walls, 15 ipm and 30 ipm.
> > >
> > > 6 line walls/perimeters is a large number.   My default setting is
> > > 2. Less perimeters also prints a lot faster.  If the part is weak,
> > > you can always increase it later, but it sounds like you are still
> > > having issue with the extrusion flow rate.
> >
> > The 2 I broke already were made before I calibrated it and found it
> > set for about 18mm of pla for a 100mm move. At 6, its buckets
> > sturdier, but the bearing bottom was 35.5mm and I killed a bearing
> > putting it together.  So I've scaled it down a wee bit and will make
> > another for the 3rd one if this one fits better.
>
> I picked the smallest bearing carrier I had assembled, stuck on that
> motor, and picked the smallest internal spline ring. Bolted it all up.
> Its been running at about 400 rpm input, and a turn every 4 seconds
> for output for longer than the other 2 together. But its crackling and
> stalling, too it apart, flexgear is good, but I think it doesn't have
> quite enough hop over clearance.  The next on on the printer should be
> a few thou smaller. This will also get me into it far enough to
> refresh that lumpy bearing.
>
> But I need some sleep while the next one is finishing.

It has, it fits perfectly in a new main bearing, and the smaller wave 
carrier I used before is in it, along with the stator ring. Its running 
quieter at about 6 rpm.  Dry, but I was looking at my cooking oil, thaws 
at 75F coconut and wondering.  Now they are telling me the si stuff I 
ordered, won't be here before Nov 7th.  I think that belongs in the WTF 
category... Another one started, this ones running and I'm going back to 
bed.

> > Thanks Frank.
> >
> > Cheers, Gene Heskett
>
> Cheers, Gene Heskett


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gregg Eshelman via Emc-users]

More perimeters = more strength in FDM printing. For rigid plastics like PLA 
that also increases stiffness.
Several years ago, Benelli was designing a new auto loading shotgun and they 
had a problem with part of the bolt breaking. They made it thicker serveral 
times, they tried different metals, they tried different hardening treatments 
but the part would always eventually break. Then they applied some better 
analysis techniques to find how the part was trying to flex when the gun was 
fired and made a bolt with that part thinner than the first one which broke. 
Allowing the part to flex stopped it from breaking, and the lighter weight 
increased the cycling speed to the point where some trick shooters were able to 
break longstanding records like how many clay targets they could hand toss into 
the air and shoot before any hit the ground.
So rather than tying to make the part ever stronger, and thus less flexible, 
you need to see what can be altered in the 3D model to make the area where it 
breaks more flexible.

On Tuesday, August 18, 2020, 5:23:58 PM MDT, Frank Tkalcevic 
 wrote:  
 > the middle of a now thicker and nuch denser 6 wall build.  cura settings 
> are for 6 line walls, 15 ipm and 30 ipm.

6 line walls/perimeters is a large number.  My default setting is 2.  Less 
perimeters also prints a lot faster.  If the part is weak, you can always 
increase it later, but it sounds like you are still having issue with the 
extrusion flow rate.  
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Tuesday 18 August 2020 20:30:45 Gene Heskett wrote:

> On Tuesday 18 August 2020 18:50:22 Frank Tkalcevic wrote:
> > > the middle of a now thicker and nuch denser 6 wall build.  cura
> > > settings are for 6 line walls, 15 ipm and 30 ipm.
> >
> > 6 line walls/perimeters is a large number.   My default setting is
> > 2. Less perimeters also prints a lot faster.  If the part is weak,
> > you can always increase it later, but it sounds like you are still
> > having issue with the extrusion flow rate.
>
> The 2 I broke already were made before I calibrated it and found it
> set for about 18mm of pla for a 100mm move. At 6, its buckets
> sturdier, but the bearing bottom was 35.5mm and I killed a bearing
> putting it together.  So I've scaled it down a wee bit and will make
> another for the 3rd one if this one fits better.
>
I picked the smallest bearing carrier I had assembled, stuck on that 
motor, and picked the smallest internal spline ring. Bolted it all up. 
Its been running at about 400 rpm input, and a turn every 4 seconds for 
output for longer than the other 2 together. But its crackling and 
stalling, too it apart, flexgear is good, but I think it doesn't have 
quite enough hop over clearance.  The next on on the printer should be a 
few thou smaller. This will also get me into it far enough to refresh 
that lumpy bearing.

But I need some sleep while the next one is finishing.
> Thanks Frank.
>
> Cheers, Gene Heskett


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Tuesday 18 August 2020 18:50:22 Frank Tkalcevic wrote:

> > the middle of a now thicker and nuch denser 6 wall build.  cura
> > settings are for 6 line walls, 15 ipm and 30 ipm.
>
> 6 line walls/perimeters is a large number.   My default setting is 2. 
> Less perimeters also prints a lot faster.  If the part is weak, you
> can always increase it later, but it sounds like you are still having
> issue with the extrusion flow rate.
>
The 2 I broke already were made before I calibrated it and found it set 
for about 18mm of pla for a 100mm move. At 6, its buckets sturdier, but 
the bearing bottom was 35.5mm and I killed a bearing putting it 
together.  So I've scaled it down a wee bit and will make another for 
the 3rd one if this one fits better.

Thanks Frank.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Frank Tkalcevic]

> the middle of a now thicker and nuch denser 6 wall build.  cura settings 
> are for 6 line walls, 15 ipm and 30 ipm.

6 line walls/perimeters is a large number.   My default setting is 2.  Less 
perimeters also prints a lot faster.  If the part is weak, you can always 
increase it later, but it sounds like you are still having issue with the 
extrusion flow rate.



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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Monday 17 August 2020 14:33:02 Chris Albertson wrote:

> "TPU" has a wide range of properties depending on the brand.   This is
> good because you can match it to what you need from very soft to a
> kind of hard rubber.   It is harder to print and not the best for
> Bowden tube printers. It is like trying to push a rubber band dow the
> tube.   My printer has the filament feed stepper motor mounted on the
> hot end.   This adds a huge amount a mass to the head but the delay
> from pushing filament to a drop coming out the nozel is less.  It is a
> design trade off.  But if you print slow enough it does not matter.


Re-thinking on how to optimize this thing for maximum life of the 
flexgear.

!. I have to make the bearing projection on the bottom of the cup, fit 
the bearing with a press fit. I've calculated the amount of change in 
the printers scale settings to do that, and have one about 30% built, as 
its about 20 hours of wall time to make one.

And I have found the "tune" menu, its seems its only visible of a print 
is in progress, which when thought about, makes sense.  Adjusting flow 
with my sockless hot end gets me motor step skip backwards at 110%, si 
ts currently running at 108%, but that was only done by raiseing the hot 
end temp from 205 to 210C. 55C bed once past the first layer, current 
speed 140% of what cura told it to, and I had to restart it about 5 
times to get the first layer to stick, finally adding a brim and 
reslicing it. If this one fits the bearing, I'll make them, 3 more and 
call that the final size.  Next is determining the bearing carrier size 
so a dial, watching the cup as its running, and size adjusted for about 
a 1.55mm movement of the splines in and out as its running.  Just enough 
expansion to get full contact at maximum, and just enough pullin at 
minimum to let the peaks pass each other.

Thats stage 2 of this things optimization, establishing just enough flex 
to make it work, but no more.

Then, and only then, trim the size of the internel spline ring to get the 
maximum stretch to bring that point into full contact.  Placing the 
bearing carrier size for the amount of flex as the 2nd adjustment then 
makes the outer ring that last thing to adjust for a more perfect fit. 
It can work on half the flex designed into the .step file now.  Which 
should give many times the life. As built from the .step file, 20 
minutes to a broken flexgear, broke at the wall bottom just above the 
fillet every time.

But a micro-swiss hot end kit with the extruder moved to the x carriage 
s/b here today, along with some tpu, and thats when I start all over as 
I am not 100% convinced PLA will take even this reduced flexing on a 
long term basis.  We shall see I guess. Yes, people, I am kicking tires 
that have not been kicked before in plastic. But I want the fact thats 
its plastic removed from the top of the failure list.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

"TPU" has a wide range of properties depending on the brand.   This is good
because you can match it to what you need from very soft to a kind of hard
rubber.   It is harder to print and not the best for Bowden tube printers.
It is like trying to push a rubber band dow the tube.   My printer has the
filament feed stepper motor mounted on the hot end.   This adds a huge
amount a mass to the head but the delay from pushing filament to a drop
coming out the nozel is less.  It is a design trade off.  But if you print
slow enough it does not matter.

I bought the TPU for finger pads for a robot gripper hand but found other
uses for it.  If you have it you will find some use for it.  If nothing
else a cell phone case.

On Mon, Aug 17, 2020 at 10:32 AM Gene Heskett  wrote:

> On Monday 17 August 2020 05:21:28 Bruce Layne wrote:
>
> > On 8/17/20 3:52 AM, Gene Heskett wrote:
> > > This one is printing at the same scale as the output shaft, which I
> > > just remade after finding they were to big to enter the main bearing
> > > even with help from the assembly screws. So this will have a smaller
> > > bore, which means I'll have to make a smaller internal spline, and
> > > that may demand a smaller bearing carrier, as I need it to push the
> > > splines fully engaged, but only enough clearance from pull-in that
> > > at the midpoint between the rollers, the tips of the splines clear
> > > each other, this condition corresponds to the minimum flex it needs
> > > to work=longest life.
> >
> > Maybe you should have started your 3D printing with a baby Yoda like
> > everyone else. :-)
>
> Actually, the waving cat was on the sd card.  Weighs less than a gram, I
> can see thru it from any angle, OOTB it was that starved for plastic.
> The flexgears I'm breaking quickly were somewhat similar in that there
> are pinholes in them that let light sparkle thru.
>
> This ones not done yet, it just started on the ramps to the splines and
> when I saw that I slowed it back down to 90% as I had it up to 170% in
> the middle of a now thicker and nuch denser 6 wall build.  cura settings
> are for 6 line walls, 15 ipm and 30 ipm. Plate cooldown after 1st layer,
> 61 to 55, and 215 for 1st layer then 200.  Structure under it is called
> zig-zag, and starts out pretty sparse, but leans into the gaps
> eventually looking pretty solid.
>
> This smaller scaled flexgear changes everything around it, so I'll stetch
> this one into an internal spline to see if it needs tweaked for size,
> making scale adjustments as needed and then diddle the scales for the
> proper size of bearing carrier, which should push it out of round,
> stretching the sides enough to let the splines hop over to the next one.
> First pass at all this only half engaged the splines, so it had backlash
> up the yang. And flexed the flexgear bad enough the splines had 2mm of
> clearance at the hop-over point. A smaller internal spline will reduce
> that clearance and the extra flexing that goes with it.
>
> The bearing carriers I have made 3 of, measure 74.84mm acroos the
> bearings, but when figuring scaling, you need to subtract the bearing
> diameter from both ratios if you want a new SWAG guess for their scale.
> So they will need to shrink by the thicker walls differences.  For a
> first guess...
>
> When the tpu gets here, is its shrinkage different?  But I'll likely wait
> until the micro-swiss hot end kit gets here and installed. Running w/o
> the sock on the hot block works that heater R about 3x as much. Looking
> at it, if I could make a baffle that goes into the hot/cold gap, keeping
> the fans breeze off the hot block, that would be nearly as good as the
> missing sock, and a heck of a lot longer lasting. A BBLB design for
> sure.
>
> Its possible the micro-swiss kit will be here tomorrow too.
>
> > >> 1500 mm/minute for all motion
> > >
> > > Thats 3x the top speed setting in merlin.
> >
> > You may be seeing mm/second units rather than the mm/minute that I
> > specified.  1500mm/min = 25mm/sec, fairly slow for a 3D printer.
>
> I think you are right. As usual. :)
>
> Thanks Bruce.
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
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>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Monday 17 August 2020 05:21:28 Bruce Layne wrote:

> On 8/17/20 3:52 AM, Gene Heskett wrote:
> > This one is printing at the same scale as the output shaft, which I
> > just remade after finding they were to big to enter the main bearing
> > even with help from the assembly screws. So this will have a smaller
> > bore, which means I'll have to make a smaller internal spline, and
> > that may demand a smaller bearing carrier, as I need it to push the
> > splines fully engaged, but only enough clearance from pull-in that
> > at the midpoint between the rollers, the tips of the splines clear
> > each other, this condition corresponds to the minimum flex it needs
> > to work=longest life.
>
> Maybe you should have started your 3D printing with a baby Yoda like
> everyone else.     :-)

Actually, the waving cat was on the sd card.  Weighs less than a gram, I 
can see thru it from any angle, OOTB it was that starved for plastic. 
The flexgears I'm breaking quickly were somewhat similar in that there 
are pinholes in them that let light sparkle thru.

This ones not done yet, it just started on the ramps to the splines and 
when I saw that I slowed it back down to 90% as I had it up to 170% in 
the middle of a now thicker and nuch denser 6 wall build.  cura settings 
are for 6 line walls, 15 ipm and 30 ipm. Plate cooldown after 1st layer, 
61 to 55, and 215 for 1st layer then 200.  Structure under it is called 
zig-zag, and starts out pretty sparse, but leans into the gaps 
eventually looking pretty solid.

This smaller scaled flexgear changes everything around it, so I'll stetch 
this one into an internal spline to see if it needs tweaked for size, 
making scale adjustments as needed and then diddle the scales for the 
proper size of bearing carrier, which should push it out of round, 
stretching the sides enough to let the splines hop over to the next one.  
First pass at all this only half engaged the splines, so it had backlash 
up the yang. And flexed the flexgear bad enough the splines had 2mm of 
clearance at the hop-over point. A smaller internal spline will reduce 
that clearance and the extra flexing that goes with it.

The bearing carriers I have made 3 of, measure 74.84mm acroos the 
bearings, but when figuring scaling, you need to subtract the bearing 
diameter from both ratios if you want a new SWAG guess for their scale.  
So they will need to shrink by the thicker walls differences.  For a 
first guess...

When the tpu gets here, is its shrinkage different?  But I'll likely wait 
until the micro-swiss hot end kit gets here and installed. Running w/o 
the sock on the hot block works that heater R about 3x as much. Looking 
at it, if I could make a baffle that goes into the hot/cold gap, keeping 
the fans breeze off the hot block, that would be nearly as good as the 
missing sock, and a heck of a lot longer lasting. A BBLB design for 
sure.

Its possible the micro-swiss kit will be here tomorrow too.

> >> 1500 mm/minute for all motion
> >
> > Thats 3x the top speed setting in merlin.
>
> You may be seeing mm/second units rather than the mm/minute that I
> specified.  1500mm/min = 25mm/sec, fairly slow for a 3D printer.

I think you are right. As usual. :)

Thanks Bruce.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Bruce Layne]

On 8/17/20 3:52 AM, Gene Heskett wrote:

> This one is printing at the same scale as the output shaft, which I just 
> remade after finding they were to big to enter the main bearing even with 
> help from the assembly screws. So this will have a smaller bore, which means 
> I'll have to make a smaller internal spline, and that may demand a smaller 
> bearing carrier, as I need it to push the splines fully engaged, but only 
> enough clearance from pull-in that at the midpoint between the rollers, the 
> tips of the splines clear each other, this condition corresponds to the 
> minimum flex it needs to work=longest life.

Maybe you should have started your 3D printing with a baby Yoda like
everyone else.     :-)



>> 1500 mm/minute for all motion
> Thats 3x the top speed setting in merlin.

You may be seeing mm/second units rather than the mm/minute that I
specified.  1500mm/min = 25mm/sec, fairly slow for a 3D printer.






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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 16 August 2020 21:33:29 Bruce Layne wrote:

> On 8/16/20 8:40 PM, Gene Heskett wrote:
> > And it ran about 5 minutes, broke the cup of the flexgear off at the
> > disk junction. Only 1.2mm thick there, concentrating the wall flex
> > into that relatively sharp corner. Can I fix that in cura? How?
>
> Cura should allow you to specify the number of layers.  In Simplify3D,
> I can set the number of bottom layers, the number of top layers and
> the number of side layers... all independently.  As Chris and I have
> maintained, the outer layers largely determine part strength and the
> infill doesn't.  I'm printing a small production run of structural
> parts and I had the slicer use four outer layers and 20% infill. 
> They're very strong ABS parts.  If I wanted rigid parts such as gears
> that were resistant to impact forces or layer separation, I might
> specify six outer layers, and possibly more.

I just did that, 7 outer layers and changed the support pattern to gyroid, and 
amazingly its building up that randomized cookie cutter pattern just fine even 
though I seen it move on the glass as it didn't "stick" but its working anyhow. 
But I can see its curling up at the start stop points of the maze its drawing. 
180 degrees apart in the pattern.  We'll see what the disk pattern looks like 
when it gets up to that.

This one is printing at the same scale as the output shaft, which I just remade 
after finding they were to big to enter the main bearing even with help from 
the assembly screws. So this will have a smaller bore, which means I'll have to 
make a smaller internal spline, and that may demand a smaller bearing carrier, 
as I need it to push the splines fully engaged, but only enough clearance from 
pull-in that at the midpoint between the rollers, the tips of the splines clear 
each other, this condition corresponds to the minimum flex it needs to 
work=longest life.

I also ordered a couple spools of TPU. But I suspect its too soft, but will try 
one for S  ABS has more give, and it may be the right stuff to try, ut its 
also temp sensitve, changeing at day to day temps.  So I'm not convinced it 
will work for something that may need to work outdoors in 0F weather or in the 
middle of the summer wiith 90F at 3AM.
.
> > Looking at that edge with a strong lens, I see 3 layers of wall,
> > with quite a bit of air too.  So I was still having plastic delivery
> > problems even after calibrating it according to Andy, where scale is
> > set to deliver 100mm of pla for a 100mm move command.
>
> That's a good calibration method but it assumes filament that is
> within specifications.  I've recently encountered some filament that I
> bought on Amazon (with good reviews) that was 1.49mm in diameter
> instead of 1.75mm +/- .03mm.  Undersized filament will cause under
> extrusion.  You should be able to compensate with a slicer setting,
> within reason, but if the filament diameter is too small it may not
> feed reliably in some extruders.  The software compensation can't
> compensate for absolute hardware limitations.

I don't expect it to.

> Properly calibrated, adjacent layers of extruded filament should touch
> each other.  You shouldn't be able to see any space between adjacent
> layers.  The layers will typically be .4mm wide, on .4mm centers, so
> they touch.  Maybe verify that your slicer knows what size nozzle
> you're using.

Done.

> It sounds like you've made a lot of adjustments to the
> settings in Cura and in the Marlin firmware, and it would be easy to
> accidentally enter a wrong value that persists and causes problems. 
> It might be a good idea to return to known good values for Cura and
> Marlin.  The people who have better luck 3D printing didn't need to do
> a lot of configurations.
>
> > Bruce mentioned TPU with an 85 or better shore as being more
> > flexible but I've not found that for sale anyplace. URL anybody?
>
> https://www.amazon.com/s?k=tpu+1.75
>
> Warning - The Priline TPU was the filament I mentioned that had an
> outer diameter of 1.49mm instead of 1.75mm.  Yoyi is pretty good TPU
> but a bit stringy.  The higher the durometer (Shore A value) the
> easier the filament is to print because it's not as soft and stringy. 

Amazon showed a D95 version but it was twice the price. What I should have 2 
spools of Tuesday was $75 for 2 .8kg spools.

> The extruder has less trouble feeding the filament, and there are
> fewer problems with stringy parts.  Each brand of TPU is different,
> but I generally use the following slicer settings for TPU:
>
> 1500 mm/minute for all motion

Thats 3x the top speed setting in merlin.

> 220C nozzle temperature

I can reach that without the sock. But its slow getting there.

> No retraction

With TPU's spring, it would need at leasr triple the PLA setting. TBD per spool 
I suspect.

> 25% speed for the first layer, no cooling fan, 60C bed temperature.
> 100% speed for all subsequent layers, 100% cooling fan speed, 50C bed
> temperature

Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Bruce Layne]

On 8/16/20 8:40 PM, Gene Heskett wrote:

> And it ran about 5 minutes, broke the cup of the flexgear off at the disk 
> junction. Only 1.2mm thick there, concentrating the wall flex into that 
> relatively sharp corner. Can I fix that in cura? How?

Cura should allow you to specify the number of layers.  In Simplify3D, I
can set the number of bottom layers, the number of top layers and the
number of side layers... all independently.  As Chris and I have
maintained, the outer layers largely determine part strength and the
infill doesn't.  I'm printing a small production run of structural parts
and I had the slicer use four outer layers and 20% infill.  They're very
strong ABS parts.  If I wanted rigid parts such as gears that were
resistant to impact forces or layer separation, I might specify six
outer layers, and possibly more.



> Looking at that edge with a strong lens, I see 3 layers of wall, with quite a 
> bit of air 
> too.  So I was still having plastic delivery problems even after 
> calibrating it according to Andy, where scale is set to deliver 100mm of 
> pla for a 100mm move command.

That's a good calibration method but it assumes filament that is within
specifications.  I've recently encountered some filament that I bought
on Amazon (with good reviews) that was 1.49mm in diameter instead of
1.75mm +/- .03mm.  Undersized filament will cause under extrusion.  You
should be able to compensate with a slicer setting, within reason, but
if the filament diameter is too small it may not feed reliably in some
extruders.  The software compensation can't compensate for absolute
hardware limitations.

Properly calibrated, adjacent layers of extruded filament should touch
each other.  You shouldn't be able to see any space between adjacent
layers.  The layers will typically be .4mm wide, on .4mm centers, so
they touch.  Maybe verify that your slicer knows what size nozzle you're
using.  It sounds like you've made a lot of adjustments to the settings
in Cura and in the Marlin firmware, and it would be easy to accidentally
enter a wrong value that persists and causes problems.  It might be a
good idea to return to known good values for Cura and Marlin.  The
people who have better luck 3D printing didn't need to do a lot of
configurations.



> Bruce mentioned TPU with an 85 or better shore as being more flexible but 
> I've not found that for sale anyplace. URL anybody?

https://www.amazon.com/s?k=tpu+1.75

Warning - The Priline TPU was the filament I mentioned that had an outer
diameter of 1.49mm instead of 1.75mm.  Yoyi is pretty good TPU but a bit
stringy.  The higher the durometer (Shore A value) the easier the
filament is to print because it's not as soft and stringy.  The extruder
has less trouble feeding the filament, and there are fewer problems with
stringy parts.  Each brand of TPU is different, but I generally use the
following slicer settings for TPU:

1500 mm/minute for all motion
220C nozzle temperature
No retraction
25% speed for the first layer, no cooling fan, 60C bed temperature.
100% speed for all subsequent layers, 100% cooling fan speed, 50C bed
temperature
Avoid crossing outer perimeter





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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 16 August 2020 18:41:50 Gene Heskett wrote:

> On Sunday 16 August 2020 18:24:03 John Dammeyer wrote:
> > -Original Message-
> >
> > > From: Gene Heskett [mailto:ghesk...@shentel.net]
> > >
> > > > Mine's a CSTAR P802M bought back in December 2015.  Has problems
> > > > but overall is like my table saw.  I go up to it.  Turn it on.
> > > > Use it. Turn it off.  I've probably printed almost 1000 parts of
> > > > various types with it now.
> > > >
> > > > I added a glass plate and underneath placed an insulating pad
> > > > bought at Home Depot used for preventing burning wood when
> > > > soldering water pipes.
> > > >
> > > > This is what it looks like.
> > > > https://www.banggood.com/TRONXY-P802M-DIY-3D-Printer-Kit-220+220
> > > >+2 40mm
> > > > -Printing-Size-Support-Off-line-Print-1_75mm-0_4mm-p-1149546.htm
> > > >l? akmCl ientCountry=CA&_warehouse=CN
> > >
> > > Looks a hair better than an Ender 3 Pro, with dual z motors. Looks
> > > like the extruder motor is in the carriage?  I like that too. I
> > > don't like the spool sitting on the table though.  And at that
> > > price, I might get one anyway.
> >
> > There are two philosophies with 3D printing.  One is you move the
> > extruder motor around with additional mass and vibration for short
> > motors. The other is the Bordon tube where the motors push through
> > the feed tube.
> >
> > Vibration verses a certain amount of flex in the supply tube that
> > then results in spring tension.  So when you don't want to print you
> > have to retract much further or it oozes out as the Bordon tube
> > relaxes. Then when it's time to extrude the first bit of filament
> > flexes the tube again before it starts applying pressure into the
> > nozzle.
> >
> > The other major problem with mine, which others have fixed and I
> > still need to, is as the extruder moves up it vibrates the sides. 
> > Others have built extensive bracing holding the top solid in 3
> > dimensions so it cannot move.
> >
> > One friend changed to a higher end unit and hasn't looked back. 
> > I'll ask him what he bought.
> >
> > I expect garbage from my 3D printer so if I get something that looks
> > half decently nice I'm pleasantly surprised.  So it's all about
> > expectations and mine are much lower than most.
> >
> > For example I printed this from 4 pieces and glued it together so I
> > could see what the final version would look like and if I had fit
> > issues.  LinuxCNC has no trouble driving the STMBL to turn this.
> > http://www.autoartisans.com/mill/HarmonicDrive/FullSize-6.jpg
> >
> > Then I went back to the CAD system and expanded for shrinkage and
> > added fillets etc to be able to make a pattern.  Still in 4 pieces.
> >
> > http://www.autoartisans.com/mill/HarmonicDrive/PrintedPattern.jpg
> >
> > A bit of body filler
> > http://www.autoartisans.com/mill/HarmonicDrive/PatternPrep-1.jpg
> > primer
> > http://www.autoartisans.com/mill/HarmonicDrive/PatternPrep-2.jpg
> > and paint
> > http://www.autoartisans.com/mill/HarmonicDrive/PatternPrep-3.jpg
> > and then a test ramming into a crucible while I continued with
> > building a crucible capable of holding 15 lbs of aluminium.
> > http://www.autoartisans.com/mill/HarmonicDrive/Pulled-1.jpg
> >
> > And then there were these.
> > http://www.autoartisans.com/images/HeartsInGym2.jpg
> >
> > I printed 300 clips that held the GE-35 RGB Christmas lights in the
> > heart frames.  The hearts showed a gold colour with random twinkles
> > in white (like silver sparkles).  On the far left is a small box
> > with 50 LEDs in the same pattern and an ESTOP button modified to not
> > have the latch.  Press the button and all 6 hearts changed to a
> > pulsating RED in the rhythm of a heart beat.  bmp BMP, bmp BMP...
> > for about 40 seconds.  Time for the bride and groom to find each
> > other and kiss. Like tinkling glasses during dinner.
> >
> > Then back to gold with white sparkles.  The hearts themselves were
> > 1/8" mahogany stiffened with frames for hanging and covered in gold
> > mylar.  I now really dislike spray glue...
> >
> > 3D printing is great where you can't do something any other way. 
> > What I have found though is it's like a drug.  The end result people
> > become like someone who only owns a hammer and everything looks like
> > a nail.
> >
> > John Dammeyer
>
> There is that too. I went back to check on it, and from the evidence.
> the heat of the motor wasn't excessive. But the motor shaft has spun
> itself loose in the bearing carrier. So the motor was still spinning
> buteverything was motionless. Now I take it apart to verify since this
> model has no portholes to see into it.
>
> Sigh...

No, the flexgear broke.  Replaced it with a spare from the first ever 
build, now back to running it again.  This gear was made before the hot 
end freezeups started, so has plenty of plastic in it, but it was made 
face down so had 2 oz of supports to break out.  We'll see how long this 
one lasts.  After the 

Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gregg Eshelman via Emc-users]

The nozzle and heat break have to be screwed into the heater block and 
tightened while it's hot. Do that when it's all cold and thermal expansion of 
the block loosens up the parts and it leaks.

On Sunday, August 16, 2020, 6:27:12 AM MDT, Gene Heskett 
 wrote:  
 On Saturday 15 August 2020 09:05:48 Gene Heskett wrote:

> Slim chance I might get the rest of the screws I need later today.

I did, almost, get enough screws to put one together & take it for a 
spin. Screw lengths very critical. Works but the motor only has enough 
torque to turn it at over 2.5 amps/coil drive.  But that will get the 
motor hot enough to soften the plastic in about 15 minutes so I quit at 
about 5.

Now the 64k$ question is, it is worth building an air cooled shaft 
extension to isolate these from the motor heat?  I'll have to think on 
that. I've been thru hell with this printer and anything I need is 3-5 
weeks away.  The whole hot end of it is a pisspoor design, leaking hot 
plastic out thru the nozzles threads. Or anyplace else. The si sock on 
it is dragging on the work as its filled up, now that its cooled, with 
about an eighth of and inch of solidified plastic from the leakage.  Its 
also ripped up from the leaking PLA glueing it to the hot end, and 
damaging it during removal.  The final fix might be a strip of teflon 
pipe tape on the nozzles threads, but that would have to be done to 
brand new, clean parts I don't have.  
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 16 August 2020 18:24:03 John Dammeyer wrote:

> -Original Message-
>
> > From: Gene Heskett [mailto:ghesk...@shentel.net]
> >
> > > Mine's a CSTAR P802M bought back in December 2015.  Has problems
> > > but overall is like my table saw.  I go up to it.  Turn it on. Use
> > > it. Turn it off.  I've probably printed almost 1000 parts of
> > > various types with it now.
> > >
> > > I added a glass plate and underneath placed an insulating pad
> > > bought at Home Depot used for preventing burning wood when
> > > soldering water pipes.
> > >
> > > This is what it looks like.
> > > https://www.banggood.com/TRONXY-P802M-DIY-3D-Printer-Kit-220+220+2
> > >40mm
> > > -Printing-Size-Support-Off-line-Print-1_75mm-0_4mm-p-1149546.html?
> > >akmCl ientCountry=CA&_warehouse=CN
> >
> > Looks a hair better than an Ender 3 Pro, with dual z motors. Looks
> > like the extruder motor is in the carriage?  I like that too. I
> > don't like the spool sitting on the table though.  And at that
> > price, I might get one anyway.
>
> There are two philosophies with 3D printing.  One is you move the
> extruder motor around with additional mass and vibration for short
> motors. The other is the Bordon tube where the motors push through the
> feed tube.
>
> Vibration verses a certain amount of flex in the supply tube that then
> results in spring tension.  So when you don't want to print you have
> to retract much further or it oozes out as the Bordon tube relaxes. 
> Then when it's time to extrude the first bit of filament flexes the
> tube again before it starts applying pressure into the nozzle.
>
> The other major problem with mine, which others have fixed and I still
> need to, is as the extruder moves up it vibrates the sides.  Others
> have built extensive bracing holding the top solid in 3 dimensions so
> it cannot move.
>
> One friend changed to a higher end unit and hasn't looked back.  I'll
> ask him what he bought.
>
> I expect garbage from my 3D printer so if I get something that looks
> half decently nice I'm pleasantly surprised.  So it's all about
> expectations and mine are much lower than most.
>
> For example I printed this from 4 pieces and glued it together so I
> could see what the final version would look like and if I had fit
> issues.  LinuxCNC has no trouble driving the STMBL to turn this.
> http://www.autoartisans.com/mill/HarmonicDrive/FullSize-6.jpg
>
> Then I went back to the CAD system and expanded for shrinkage and
> added fillets etc to be able to make a pattern.  Still in 4 pieces.
>
> http://www.autoartisans.com/mill/HarmonicDrive/PrintedPattern.jpg
>
> A bit of body filler
> http://www.autoartisans.com/mill/HarmonicDrive/PatternPrep-1.jpg
> primer
> http://www.autoartisans.com/mill/HarmonicDrive/PatternPrep-2.jpg
> and paint
> http://www.autoartisans.com/mill/HarmonicDrive/PatternPrep-3.jpg
> and then a test ramming into a crucible while I continued with
> building a crucible capable of holding 15 lbs of aluminium.
> http://www.autoartisans.com/mill/HarmonicDrive/Pulled-1.jpg
>
> And then there were these.
> http://www.autoartisans.com/images/HeartsInGym2.jpg
>
> I printed 300 clips that held the GE-35 RGB Christmas lights in the
> heart frames.  The hearts showed a gold colour with random twinkles in
> white (like silver sparkles).  On the far left is a small box with 50
> LEDs in the same pattern and an ESTOP button modified to not have the
> latch.  Press the button and all 6 hearts changed to a pulsating RED
> in the rhythm of a heart beat.  bmp BMP, bmp BMP... for about 40
> seconds.  Time for the bride and groom to find each other and kiss. 
> Like tinkling glasses during dinner.
>
> Then back to gold with white sparkles.  The hearts themselves were
> 1/8" mahogany stiffened with frames for hanging and covered in gold
> mylar.  I now really dislike spray glue...
>
> 3D printing is great where you can't do something any other way.  What
> I have found though is it's like a drug.  The end result people become
> like someone who only owns a hammer and everything looks like a nail.
>
> John Dammeyer

There is that too. I went back to check on it, and from the evidence. the 
heat of the motor wasn't excessive. But the motor shaft has spun itself 
loose in the bearing carrier. So the motor was still spinning 
buteverything was motionless. Now I take it apart to verify since this 
model has no portholes to see into it.

Sigh...

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[John Dammeyer]

-Original Message-
> From: Gene Heskett [mailto:ghesk...@shentel.net]
> > Mine's a CSTAR P802M bought back in December 2015.  Has problems but
> > overall is like my table saw.  I go up to it.  Turn it on. Use it.
> > Turn it off.  I've probably printed almost 1000 parts of various types
> > with it now.
> >
> > I added a glass plate and underneath placed an insulating pad bought
> > at Home Depot used for preventing burning wood when soldering water
> > pipes.
> >
> > This is what it looks like.
> > https://www.banggood.com/TRONXY-P802M-DIY-3D-Printer-Kit-220+220+240mm
> >-Printing-Size-Support-Off-line-Print-1_75mm-0_4mm-p-1149546.html?akmCl
> >ientCountry=CA&_warehouse=CN
> 
> Looks a hair better than an Ender 3 Pro, with dual z motors. Looks like
> the extruder motor is in the carriage?  I like that too. I don't like
> the spool sitting on the table though.  And at that price, I might get
> one anyway.
> 

There are two philosophies with 3D printing.  One is you move the extruder 
motor around with additional mass and vibration for short motors. The other is 
the Bordon tube where the motors push through the feed tube.

Vibration verses a certain amount of flex in the supply tube that then results 
in spring tension.  So when you don't want to print you have to retract much 
further or it oozes out as the Bordon tube relaxes.  Then when it's time to 
extrude the first bit of filament flexes the tube again before it starts 
applying pressure into the nozzle.

The other major problem with mine, which others have fixed and I still need to, 
is as the extruder moves up it vibrates the sides.  Others have built extensive 
bracing holding the top solid in 3 dimensions so it cannot move.

One friend changed to a higher end unit and hasn't looked back.  I'll ask him 
what he bought.

I expect garbage from my 3D printer so if I get something that looks half 
decently nice I'm pleasantly surprised.  So it's all about expectations and 
mine are much lower than most.

For example I printed this from 4 pieces and glued it together so I could see 
what the final version would look like and if I had fit issues.  LinuxCNC has 
no trouble driving the STMBL to turn this.  
http://www.autoartisans.com/mill/HarmonicDrive/FullSize-6.jpg

Then I went back to the CAD system and expanded for shrinkage and added fillets 
etc to be able to make a pattern.  Still in 4 pieces.

http://www.autoartisans.com/mill/HarmonicDrive/PrintedPattern.jpg

A bit of body filler 
http://www.autoartisans.com/mill/HarmonicDrive/PatternPrep-1.jpg
primer 
http://www.autoartisans.com/mill/HarmonicDrive/PatternPrep-2.jpg 
and paint
http://www.autoartisans.com/mill/HarmonicDrive/PatternPrep-3.jpg
and then a test ramming into a crucible while I continued with building a 
crucible capable of holding 15 lbs of aluminium.
http://www.autoartisans.com/mill/HarmonicDrive/Pulled-1.jpg

And then there were these.
http://www.autoartisans.com/images/HeartsInGym2.jpg
 
I printed 300 clips that held the GE-35 RGB Christmas lights in the heart 
frames.  The hearts showed a gold colour with random twinkles in white (like 
silver sparkles).  On the far left is a small box with 50 LEDs in the same 
pattern and an ESTOP button modified to not have the latch.  Press the button 
and all 6 hearts changed to a pulsating RED in the rhythm of a heart beat.  bmp 
BMP, bmp BMP... for about 40 seconds.  Time for the bride and groom to find 
each other and kiss.  Like tinkling glasses during dinner.

Then back to gold with white sparkles.  The hearts themselves were 1/8" 
mahogany stiffened with frames for hanging and covered in gold mylar.  I now 
really dislike spray glue...

3D printing is great where you can't do something any other way.  What I have 
found though is it's like a drug.  The end result people become like someone 
who only owns a hammer and everything looks like a nail.

John Dammeyer
 





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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 16 August 2020 15:21:24 John Dammeyer wrote:

> > From: Gene Heskett [mailto:ghesk...@shentel.net]
> >
> > On Sunday 16 August 2020 11:57:31 John Dammeyer wrote:
> > > What type of 3D printer did you buy?
> >
> > A Creality Ender 3 Pro. Quite highly recommended.
>
> Mine's a CSTAR P802M bought back in December 2015.  Has problems but
> overall is like my table saw.  I go up to it.  Turn it on. Use it.
> Turn it off.  I've probably printed almost 1000 parts of various types
> with it now.
>
> I added a glass plate and underneath placed an insulating pad bought
> at Home Depot used for preventing burning wood when soldering water
> pipes.
>
> This is what it looks like.
> https://www.banggood.com/TRONXY-P802M-DIY-3D-Printer-Kit-220+220+240mm
>-Printing-Size-Support-Off-line-Print-1_75mm-0_4mm-p-1149546.html?akmCl
>ientCountry=CA&_warehouse=CN

Looks a hair better than an Ender 3 Pro, with dual z motors. Looks like 
the extruder motor is in the carriage?  I like that too. I don't like 
the spool sitting on the table though.  And at that price, I might get 
one anyway.

> My POS Delta printer has two Borden tubes for the dual extruder. 
> Another reason it's called a POS.  One day I may find the time to
> finish upgrading it so it actually works.  Cost twice as much as the
> P802M and has printed something 3 times before I got fed up with it.  
> I even bought a Replicape and two different Manga screens for the
> BeagleBone but never got around to installing those either.
>
> John
>
>
>
>
>
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> https://lists.sourceforge.net/lists/listinfo/emc-users


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 16 August 2020 13:51:37 Bruce Layne wrote:

> On 8/16/20 1:07 PM, Gene Heskett wrote:
> > the guy on y-t showing a razor blade being used in a jig,
> > hopefully to get a square cut. Not having a razor blade, or the jig
> > he was using, I cut it about half a mm long and took the hot block
> > with it sticking out to a piece of 320 sandpaper and sanded it flat,
> > reversed the tubing and sanded the other end flat.
>
> The extruder on my 3D printer uses a short piece of 4mm OD PTFE tubing
> as the heat break between the hot end and the cold end.  This part
> needs to be replaced when clearing a clogged nozzle.  I designed and
> 3D printed a miniature miter block that guides an X-Acto knife to make
> a clean perpendicular cut so I could make a pile of replacement PTFE
> tubes.

Finally, SUCCESS at making it run on minimum current and heating of the 
motor.

Seems I had the bearing carrier upside down, which placed the bearings 
too deep in the flexgear. And that raised the motor loading. Turned it 
over, which put the bearings at about the middle of the internal splines 
ring, ran it on half power for about 15 minutes to warm up the motor, 
then switched it down to minimum current, and its sitting on the kitchen 
counter doing about 30 output revs just to see how hot it gets in 2 or 4 
hours.  So all is not lost yet!  And that one has the biggest carrier I 
made in it, the other 2 are about .5mm smaller and have more backlash 
because they aren't quite bottoming the splines at max engagement.

Now that I know it can work at non-destructive temps, the project is back 
on.  Time for some din-din and make more coffee, that pot has had 2 days 
to cool.

Thanks all.
Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 16 August 2020 13:51:37 Bruce Layne wrote:

> On 8/16/20 1:07 PM, Gene Heskett wrote:
> > the guy on y-t showing a razor blade being used in a jig,
> > hopefully to get a square cut. Not having a razor blade, or the jig
> > he was using, I cut it about half a mm long and took the hot block
> > with it sticking out to a piece of 320 sandpaper and sanded it flat,
> > reversed the tubing and sanded the other end flat.
>
> The extruder on my 3D printer uses a short piece of 4mm OD PTFE tubing
> as the heat break between the hot end and the cold end.  This part
> needs to be replaced when clearing a clogged nozzle.  I designed and
> 3D printed a miniature miter block that guides an X-Acto knife to make
> a clean perpendicular cut so I could make a pile of replacement PTFE
> tubes.

Thats the one.  For stock E3 hot ends?  I just ordered a micro-swiss kit 
that moves the ejector to the carriage and changes the hot end design to 
kill the leakage. Better design although I think I have finally got it 
sealed, well enough it isn't spitting out plastic down the nozzles 
threads.  For about 4 hours, I have the last piece working at 300% of 
the speeds set in cura. Other than the fan vibration ripple in the 
laydown its looking good, and w/o that si rubber sock.  Slow to heat the 
ejector though, and it would not ever get to abs temps w/o that sock.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 16 August 2020 13:07:41 Gene Heskett wrote:

> On Sunday 16 August 2020 11:57:31 John Dammeyer wrote:
> > What type of 3D printer did you buy?
>
> A Creality Ender 3 Pro. Quite highly recommended.
>
> > > -Original Message-
> > > From: Gene Heskett [mailto:ghesk...@shentel.net]
> > > Sent: August-16-20 5:24 AM
> > > To: emc-users@lists.sourceforge.net
> > > Subject: Re: [Emc-users] found a harmonic drive set of .stl's on
> > > thingiverse
> > >
> > > On Saturday 15 August 2020 09:05:48 Gene Heskett wrote:
> > > > Slim chance I might get the rest of the screws I need later
> > > > today.
> > >
> > > I did, almost, get enough screws to put one together & take it for
> > > a spin. Screw lengths very critical. Works but the motor only has
> > > enough torque to turn it at over 2.5 amps/coil drive.  But that
> > > will get the motor hot enough to soften the plastic in about 15
> > > minutes so I quit at about 5.
> > >
> > > Now the 64k$ question is, it is worth building an air cooled shaft
> > > extension to isolate these from the motor heat?  I'll have to
> > > think on that. I've been thru hell with this printer and anything
> > > I need is 3-5 weeks away.  The whole hot end of it is a pisspoor
> > > design, leaking hot plastic out thru the nozzles threads. Or
> > > anyplace else. The si sock on it is dragging on the work as its
> > > filled up, now that its cooled, with about an eighth of and inch
> > > of solidified plastic from the leakage.  Its also ripped up from
> > > the leaking PLA glueing it to the hot end, and damaging it during
> > > removal.  The final fix might be a strip of teflon pipe tape on
> > > the nozzles threads, but that would have to be done to brand new,
> > > clean parts I don't have.
> > >
> > > > And thats the news from Lake Woebegon. :(
>
> I have an inquiry in at PrintedSolid.com for a bullseye hot end
> conversion kit WITH a new ptfe bowden tube, but being the weekend, no
> reply as yet. I like that design better than this one whose weak point
> is the shark bite style connection used at the top of the hot end.  No
> provision to maintain the pressure of the tube against the nozzle, so
> as the tube twists with the x motions, it gradually cuts the shark
> fingers into the plastic of the tube, and the pressure and the
> twisting wears ditches in the tube wall letting it back away from the
> rear face of the nozzle.  That lets hot plastic backup the outside of
> the tube until it cools and freezes as a big plug trapped between the
> now retracted end of the tubing and the nozzle.  And the ejector motor
> just sits there skipping steps.
>
> There is a possible fix, which consists of cutting a piece of the
> tubeing off just long enough to fill the space between the shark bite
> and the nozzle, so I've done that, and placed a teeny steel washer
> above it, so the rear of the shark bite then traps the tubing against
> the back of the nozzle, the guy on y-t showing a razor blade being
> used in a jig, hopefully to get a square cut. Not having a razor
> blade, or the jig he was using, I cut it about half a mm long and took
> the hot block with it sticking out to a piece of 320 sandpaper and
> sanded it flat, reversed the tubing and sanded the other end flat.
> This left the shark bite about 1/2 turn from tight when it was
> clamped, which I noticed was turning with the motion halfway thru the
> next part, so I took the wrench and drove it tight while it was
> printing, releasing and relocking the shark bite before restarting the
> next part. But the silicon rubber sock on the hot block is so badly
> damaged from being filled up by hot plastic coming down past the
> nozzles threads that its no longer staying in place like it should. 
> And the shark bites grip on the long tube is on only whats inside the
> shark bite.  I don't expect it to last forever before the locking
> fingers slide off the end of the tube.
>
> Hence the query about the bullseye hot end conversion kit. Guessing
> about half the cost of a new printer. I asked for a meter of the
> teflon tubing and some spare nozzles since thats a different design.
> Includes a new cooling fan, mine is rattling its cage as I broke a
> blade off trying to clear a dust bunny from it while it was running.
>
And I wound up buying a micro swiss hot end, it moves the ejector motor 
to the hot end carriage too, but doesn't replace my broken fan. All 
joints are cold in this design.

As a side note, I have it doing the last of 3 output shafts that actually 
are a press fit in the main bearing, running without the silicon sock on 
the hot block. When this is done, I've dialed it up to 300% speed, seems 
to be doing ok. I'll measure the DC psu, as enders were made in both 12 
and 24 volt versions, and I can't find a voltage marked anyplace, and I 
need to buy fans that match the voltage.  I suspect, from the heavy 
gauge of the output cable that its a 12 volt model.

> Cheers, Gene Heskett


Cheers, Gene Heskett
-- 
"There are 

Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[John Dammeyer]

> From: Gene Heskett [mailto:ghesk...@shentel.net]
> On Sunday 16 August 2020 11:57:31 John Dammeyer wrote:
> 
> > What type of 3D printer did you buy?
> A Creality Ender 3 Pro. Quite highly recommended.
> 

Mine's a CSTAR P802M bought back in December 2015.  Has problems but overall is 
like my table saw.  I go up to it.  Turn it on. Use it. Turn it off.  I've 
probably printed almost 1000 parts of various types with it now.

I added a glass plate and underneath placed an insulating pad bought at Home 
Depot used for preventing burning wood when soldering water pipes.   

This is what it looks like.
https://www.banggood.com/TRONXY-P802M-DIY-3D-Printer-Kit-220+220+240mm-Printing-Size-Support-Off-line-Print-1_75mm-0_4mm-p-1149546.html?akmClientCountry=CA&_warehouse=CN

My POS Delta printer has two Borden tubes for the dual extruder.  Another 
reason it's called a POS.  One day I may find the time to finish upgrading it 
so it actually works.  Cost twice as much as the P802M and has printed 
something 3 times before I got fed up with it.   I even bought a Replicape and 
two different Manga screens for the BeagleBone but never got around to 
installing those either.

John





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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Bruce Layne]

On 8/16/20 1:07 PM, Gene Heskett wrote:
> the guy on y-t showing a razor blade being used in a jig, 
> hopefully to get a square cut. Not having a razor blade, or the jig he 
> was using, I cut it about half a mm long and took the hot block with it 
> sticking out to a piece of 320 sandpaper and sanded it flat, reversed 
> the tubing and sanded the other end flat.

The extruder on my 3D printer uses a short piece of 4mm OD PTFE tubing
as the heat break between the hot end and the cold end.  This part needs
to be replaced when clearing a clogged nozzle.  I designed and 3D
printed a miniature miter block that guides an X-Acto knife to make a
clean perpendicular cut so I could make a pile of replacement PTFE tubes.



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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 16 August 2020 11:57:31 John Dammeyer wrote:

> What type of 3D printer did you buy?
A Creality Ender 3 Pro. Quite highly recommended.

> > -Original Message-
> > From: Gene Heskett [mailto:ghesk...@shentel.net]
> > Sent: August-16-20 5:24 AM
> > To: emc-users@lists.sourceforge.net
> > Subject: Re: [Emc-users] found a harmonic drive set of .stl's on
> > thingiverse
> >
> > On Saturday 15 August 2020 09:05:48 Gene Heskett wrote:
> > > Slim chance I might get the rest of the screws I need later today.
> >
> > I did, almost, get enough screws to put one together & take it for a
> > spin. Screw lengths very critical. Works but the motor only has
> > enough torque to turn it at over 2.5 amps/coil drive.  But that will
> > get the motor hot enough to soften the plastic in about 15 minutes
> > so I quit at about 5.
> >
> > Now the 64k$ question is, it is worth building an air cooled shaft
> > extension to isolate these from the motor heat?  I'll have to think
> > on that. I've been thru hell with this printer and anything I need
> > is 3-5 weeks away.  The whole hot end of it is a pisspoor design,
> > leaking hot plastic out thru the nozzles threads. Or anyplace else.
> > The si sock on it is dragging on the work as its filled up, now that
> > its cooled, with about an eighth of and inch of solidified plastic
> > from the leakage.  Its also ripped up from the leaking PLA glueing
> > it to the hot end, and damaging it during removal.  The final fix
> > might be a strip of teflon pipe tape on the nozzles threads, but
> > that would have to be done to brand new, clean parts I don't have.
> >
> > > And thats the news from Lake Woebegon. :(
I have an inquiry in at PrintedSolid.com for a bullseye hot end 
conversion kit WITH a new ptfe bowden tube, but being the weekend, no 
reply as yet. I like that design better than this one whose weak point 
is the shark bite style connection used at the top of the hot end.  No 
provision to maintain the pressure of the tube against the nozzle, so as 
the tube twists with the x motions, it gradually cuts the shark fingers 
into the plastic of the tube, and the pressure and the twisting wears 
ditches in the tube wall letting it back away from the rear face of the 
nozzle.  That lets hot plastic backup the outside of the tube until it 
cools and freezes as a big plug trapped between the now retracted end of 
the tubing and the nozzle.  And the ejector motor just sits there 
skipping steps.

There is a possible fix, which consists of cutting a piece of the tubeing 
off just long enough to fill the space between the shark bite and the 
nozzle, so I've done that, and placed a teeny steel washer above it, so 
the rear of the shark bite then traps the tubing against the back of the 
nozzle, the guy on y-t showing a razor blade being used in a jig, 
hopefully to get a square cut. Not having a razor blade, or the jig he 
was using, I cut it about half a mm long and took the hot block with it 
sticking out to a piece of 320 sandpaper and sanded it flat, reversed 
the tubing and sanded the other end flat. This left the shark bite about 
1/2 turn from tight when it was clamped, which I noticed was turning 
with the motion halfway thru the next part, so I took the wrench and 
drove it tight while it was printing, releasing and relocking the shark 
bite before restarting the next part. But the silicon rubber sock on the 
hot block is so badly damaged from being filled up by hot plastic coming 
down past the nozzles threads that its no longer staying in place like 
it should.  And the shark bites grip on the long tube is on only whats 
inside the shark bite.  I don't expect it to last forever before the 
locking fingers slide off the end of the tube.

Hence the query about the bullseye hot end conversion kit. Guessing about 
half the cost of a new printer. I asked for a meter of the teflon tubing 
and some spare nozzles since thats a different design. Includes a new 
cooling fan, mine is rattling its cage as I broke a blade off trying to 
clear a dust bunny from it while it was running.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[John Dammeyer]

What type of 3D printer did you buy?

> -Original Message-
> From: Gene Heskett [mailto:ghesk...@shentel.net]
> Sent: August-16-20 5:24 AM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse
> 
> On Saturday 15 August 2020 09:05:48 Gene Heskett wrote:
> 
> > Slim chance I might get the rest of the screws I need later today.
> 
> I did, almost, get enough screws to put one together & take it for a
> spin. Screw lengths very critical. Works but the motor only has enough
> torque to turn it at over 2.5 amps/coil drive.  But that will get the
> motor hot enough to soften the plastic in about 15 minutes so I quit at
> about 5.
> 
> Now the 64k$ question is, it is worth building an air cooled shaft
> extension to isolate these from the motor heat?  I'll have to think on
> that. I've been thru hell with this printer and anything I need is 3-5
> weeks away.  The whole hot end of it is a pisspoor design, leaking hot
> plastic out thru the nozzles threads. Or anyplace else. The si sock on
> it is dragging on the work as its filled up, now that its cooled, with
> about an eighth of and inch of solidified plastic from the leakage.  Its
> also ripped up from the leaking PLA glueing it to the hot end, and
> damaging it during removal.  The final fix might be a strip of teflon
> pipe tape on the nozzles threads, but that would have to be done to
> brand new, clean parts I don't have.
> 
> > And thats the news from Lake Woebegon. :(
> 
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
> 
> 
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Saturday 15 August 2020 09:05:48 Gene Heskett wrote:

> Slim chance I might get the rest of the screws I need later today.

I did, almost, get enough screws to put one together & take it for a 
spin. Screw lengths very critical. Works but the motor only has enough 
torque to turn it at over 2.5 amps/coil drive.  But that will get the 
motor hot enough to soften the plastic in about 15 minutes so I quit at 
about 5.

Now the 64k$ question is, it is worth building an air cooled shaft 
extension to isolate these from the motor heat?  I'll have to think on 
that. I've been thru hell with this printer and anything I need is 3-5 
weeks away.  The whole hot end of it is a pisspoor design, leaking hot 
plastic out thru the nozzles threads. Or anyplace else. The si sock on 
it is dragging on the work as its filled up, now that its cooled, with 
about an eighth of and inch of solidified plastic from the leakage.  Its 
also ripped up from the leaking PLA glueing it to the hot end, and 
damaging it during removal.  The final fix might be a strip of teflon 
pipe tape on the nozzles threads, but that would have to be done to 
brand new, clean parts I don't have.

> And thats the news from Lake Woebegon. :(

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

Update: Back to production on this ratty bit of plastic. Had a heck of a 
time getting the last, and still a bit small, bearing carrier made 
yesterday, because the ejector motor was back hopping and I had to slow 
the feed rate way down and help the fiber from time to time, coming to 
the conclusion the the plug was above the nozzle.  So I took it apart 
again this morning and found the bowden tube had backed out a little 
over an eight inch, leaving a huge plug of tube diameter plastic above 
the nozzle.  So I warmed it up to about 220C and cleaned it out with 
q-tips. 

Seeing a you tube video where a guy named Tim had printed a washer, 
cutting his bowden tube so its upper end inserted into the hot end, was 
sitting a few thou above the shark bites bottom, so when the shark bite 
was screwed it, that section of the tube was somewhat compressed against 
the tip, so I did a shade tree mechs version of his printed washer under 
the shark bite using a steel flat washer thats about the right size for 
a 2-56 screw, putting it between the bottom of the shark bite and the 
tubing, and inserting a piece of fiber to align its hole with the tubing 
as I tightened it about half a turn past contact, then molded the cut 
with flush cutters tube back to round, inserted it back into the shark 
bite.  Checked it for pullout.  Set it up to make an even bigger bearing 
cap but at the same temps I used yesterday to stop the heat from 
crawling up into the red sink. 194C extruder, 55C bed. Hotter only for 
the first layer. It laid a .022 thick priming track on the bed and the 
ejector motor is happy, cranked up the feed rate, doing that carrier at 
200%, extruder motor is happy despite the lower than default temp.  I 
think, if it prints the cap just as well, that 99% of my troubles with 
this BBLB printer are over. Until that tubing falls prey to the heat. :(

Slim chance I might get the rest of the screws I need later today.

And thats the news from Lake Woebegon. :)

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[cogoman via Emc-users]

While this is late in this thread, and I don't know if this has been 
covered, but hackaday had an article on a guy who has a program to 
generate cycloidal gears.  They may not have as great gear ratios as a 
harmonic drive, but might help someone looking over this thread, so here 
goes:


https://hackaday.com/2020/08/14/robotic-arm-sports-industrial-design-3d-printed-cycloidal-gears/

That is for the hackaday article,

https://forum.onshape.com/discussion/7567/cycloidal-gear-generator

That is where he posted the software.

On 7/19/20 7:58 PM, Gene Heskett wrote:

Hopefully I can put it together correctly, there are no text files and I
haven't the foggiest what bearings I'll need, or what brand of grease.

Cheers, Gene Heskett




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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

I think FreeCAD is what they call "parametric".  This means I can do things
like making a square 3X by 2X long and the ratio will always be 3:2.   But
I can also make the box 6 by 4.   If a scale factor like "X" is used is
totally up to the person who made the part.It is much shared to make a
parametric model than to make a fixed size model so most as fixed size.

So, if what you are looking for depends on the person who designed this and
not on FreeCAD.

My guess is your.step file is made with fixed dimension

On Thu, Aug 13, 2020 at 2:20 AM Gene Heskett  wrote:

>
> As I have discovered. But I'll have to become MUCH more expert at
> freecad, so far I haven't figured out how to get an editable format out
> of freecad that shows me the tooth counts and profiles, and how they
> could be individually adjusted for a better fit, then re-locked together
> so the whole thing could be adjusted in size and remain functional.

-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Thursday 13 August 2020 05:29:04 Gene Heskett wrote:

> On Thursday 13 August 2020 02:17:00 Chris Albertson wrote:
> > On Mon, Jul 20, 2020 at 2:40 AM Gene Heskett 
>
> wrote:
> > > Am I supposed to be able to write the cura output gcode file to
> > > the printers u-sd card while its printing a differennt file? That
> > > would be handy, replacing the sneakernet I'm doing now.
> >
> > I set up Octoprint a while back.  It works well.  My printer
> > connects to the same I use for LinuxCNC with a USB cable.  I can now
> > drag and drop on my Mac.  I just drag a g-code file to octoprint.  I
> > have a webcam and octoprint streams the video of the printer and
> > also makes some plots of things like temperature vs. time for me.   
> > The neat thing is that I can monitor the printing process from any
> > place even on my phone.
> >
> > I am still not understanding why you prints are going so slowly.  At
> > 20% infilland 2 lines per wall it should be faster.
>
> At the expense of weaker parts. I let it use the default 40% and 4
> lines per wall, and am just now looking at 30% and 3 lines. re-slicing
> the internal spline, I got rid of the startup woes as it was laying
> down all the outlines as a single line, then knocking them loose
> trying to build on them.  Messy cuz it blue tints the air.  This time
> its doing all the infill first, which gives it plenty of well stuck
> material to attach the other stuff to.  Now if its still the same
> size... I should be able to check that in around 4 or 5 hours.

Much much much cleaner print, stuck very well, near perfect fit, even on 
1st layer, but I'd increased the tension on the extruder drive, so now 
for the first 2 layers, the motor is hopping backwards instead of 
grinding away the fiber, needs higher extruder temp maybe as I'd gone 
back to 200C, 60C. Making another to replace an earlier & sloppy one. 8 
hrs, 18 minutes predicted.  Best stuff I've made yet.

This is all at .12mm layer, super quality cura calls it,  body stuff 
could be done much faster but I still letting this thing teach me. :)

Now if I had the assembly screws and nuts.  Got a drawer full of screws, 
but no M4 nuts. And I need to locate some 18mm long M3 cap screws for 
the bearing holders

> Thanks Chris.
>
> Cheers, Gene Heskett


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Thursday 13 August 2020 02:17:00 Chris Albertson wrote:

> On Mon, Jul 20, 2020 at 2:40 AM Gene Heskett  
wrote:
> > Am I supposed to be able to write the cura output gcode file to the
> > printers u-sd card while its printing a differennt file? That would
> > be handy, replacing the sneakernet I'm doing now.
>
> I set up Octoprint a while back.  It works well.  My printer connects
> to the same I use for LinuxCNC with a USB cable.  I can now drag and
> drop on my Mac.  I just drag a g-code file to octoprint.  I have a
> webcam and octoprint streams the video of the printer and also makes
> some plots of things like temperature vs. time for me.The neat
> thing is that I can monitor the printing process from any place even
> on my phone.
>
> I am still not understanding why you prints are going so slowly.  At
> 20% infilland 2 lines per wall it should be faster.

At the expense of weaker parts. I let it use the default 40% and 4 lines 
per wall, and am just now looking at 30% and 3 lines. re-slicing the 
internal spline, I got rid of the startup woes as it was laying down all 
the outlines as a single line, then knocking them loose trying to build 
on them.  Messy cuz it blue tints the air.  This time its doing all the 
infill first, which gives it plenty of well stuck material to attach the 
other stuff to.  Now if its still the same size... I should be able to 
check that in around 4 or 5 hours.

Thanks Chris.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Thursday 13 August 2020 02:06:56 Chris Albertson wrote:

> On Sun, Jul 19, 2020 at 5:39 PM Gene Heskett  
wrote:
> > The zip contains a .step file. What does linux use to render/view
> > that? That file does contain the bearing part numbers,
>
> A ".step" file can be opened in any 3D CAD program.  With Linux
> FreeCAD or Onshape.
>
> I would suggest just deleting any STL files and using the .step file
> to make you own STL files that way you have an editable file.  STL
> files are very hard to edit

As I have discovered. But I'll have to become MUCH more expert at 
freecad, so far I haven't figured out how to get an editable format out 
of freecad that shows me the tooth counts and profiles, and how they 
could be individually adjusted for a better fit, then re-locked together 
so the whole thing could be adjusted in size and remain functional.  
That would be my target. For the telescope, which is a well balanced 
piece of work if assembled and the counter-weights are properly 
adjusted, a rather small force can manhandle a rather ungainly sized bit 
of mostly empty air.  This particular unit is designed to be driven by a 
nema-17 motor, and the commercial stuff made today by Meade and 
Celestron, is moved by electric clock motors in the desktop versions.

And obviously has backlash, intended to be handled by leaving it slightly 
out of balance and always approaching the star it's being aimed at from 
the same final direction.   But the last one really should up up-sized 
to be operated by a larger nema-23 of say 3NM torque if its to be hooked 
to the worm of a BS-1 clone, and moved as its used to cut gears as I see 
being done by Andy's videos.

Freecad has in the past been such a moving target that the tuts are 
worthless 3 months later.

So the first thing to do in freecad, is to find in that .step file, where 
its sizes can be interlocked and cross-coupled, so smaller, or larger 
versions of it can be made just by adjusting one MASTER SCALE value. But 
at the same time still useing readily available metric bolts to build it 
with.

For instance, I just noted yesterday, that there are no nut pockets in 
one side of the bearing carrier, so if using M3 hex nuts to assemble it, 
either there needs to be swinging clearance for the nuts, (there is now) 
but the 14mm long bolts specced needs to grow to 16mm to gain the extra 
length to reach the nut if its on the surface. IOW if one side has 
counterbores for the head of a 3mm allen head cap screw, I'd expect the 
other side to have a nut pocket. I'd also expect that the nut carriers 
sticking up from the thicker side of that part would grow in height to 
lock into or thru the capping part on the opposite side in order to long 
withstand the pressure of adequately tightening the grub screws to the 
motor shaft. Final assembly will include a dab of JBWeld on the mating 
faces there. That is one of the reasons I will mount the motor on the 
GO704, mount the the CBN cup I have in the spindle, power up the motor 
to hold its position, and make the motor shaft into a double D-flat so 
both grub screws are sitting on the flats. That CBN wheel is amazing 
once I got the arbor to hold it straight and true.

Thats progress but not in the direction of being able to use freecad as 
as editor. That I haven't grokked yet.

Thanks Chris.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

On Mon, Jul 20, 2020 at 2:40 AM Gene Heskett  wrote:

>
> Am I supposed to be able to write the cura output gcode file to the
> printers u-sd card while its printing a differennt file? That would be
> handy, replacing the sneakernet I'm doing now.
>

I set up Octoprint a while back.  It works well.  My printer connects to
the same I use for LinuxCNC with a USB cable.  I can now drag and drop on
my Mac.  I just drag a g-code file to octoprint.  I have a webcam and
octoprint streams the video of the printer and also makes some plots of
things like temperature vs. time for me.The neat thing is that I can
monitor the printing process from any place even on my phone.

I am still not understanding why you prints are going so slowly.  At 20%
infilland 2 lines per wall it should be faster.

>
>
> ___
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-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Chris Albertson]

On Sun, Jul 19, 2020 at 5:39 PM Gene Heskett  wrote:

>
> The zip contains a .step file. What does linux use to render/view that?
> That file does contain the bearing part numbers,


A ".step" file can be opened in any 3D CAD program.  With Linux FreeCAD or
Onshape.

I would suggest just deleting any STL files and using the .step file to
make you own STL files that way you have an editable file.  STL files are
very hard to edit
-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Wednesday 12 August 2020 23:30:03 Greg Bernard wrote:

> McMaster-Carr has 4 mm square nuts in stock.
>
Thank you Greg, be shipped in the morning.  Had to reset my pw, I'd 
changed browsers. But its done.

> On Wed, Aug 12, 2020, 8:39 PM Gene Heskett  
wrote:
> > On Wednesday 12 August 2020 15:55:39 grumpy--- via Emc-users wrote:
> > > On Wed, 12 Aug 2020, Gene Heskett wrote:
> > > > On Wednesday 12 August 2020 12:45:14 grumpy--- via Emc-users 
wrote:
> > > >> gene, how is this project come'n
> > > >> i keep look'n for pictures on your web site
> > > >
> > > > That will happen eventually but progress was slow when I started
> > > > out with a printer that was totally uncalibrated OOTB. So once I
> > > > got that figured out, the extruder was only feeding about 13mm
> > > > of plastic for a 100mm feed. Then it was make flexgears creeping
> > > > up on the right size to actually fit in the main bearing, you
> > > > have to make it at least 3 red hairs small because the printer
> > > > bleeds that much. So about 8 of them later, I finally have 3
> > > > that fit.  Then the size of the internal spline is too large for
> > > > that sized gear, and I just now took the 2nd good one off the
> > > > printer and may make the last one at another .05 less on the
> > > > printers xy scales as there is still 15-20 thou of clearance
> > > > between the teeth at maximum pullin on the sides of the bearing
> > > > carrier. That will be added to by the fact that the bearing
> > > > carrier is carrying 6 bearings in groups of 3. So I just reduced
> > > > the scale to 79.85 from 79.9 as I believe there is room yet to
> > > > tighten that up another few thou.  The closer that is, the less
> > > > actual flexing the flexgear has to do and it won't fatigue and
> > > > break so quick.
> > > >
> > > > I have already made some bearing carriers, but may have
> > > > stretched them too much before I found the flexgears were too
> > > > big for the bearings.  So that fit has not been pronounced as
> > > > good yet.
> > > >
> > > > The idea then is to scale the bearing carrier for a teeny bit of
> > > > overpush, flexing the houseing and circular spline a thou or 4
> > > > for a break-in wear clearance, keeping it backlash free a bit
> > > > longer.
> > > >
> > > > The third one, if it has the cajones for the job, will be
> > > > turning the worm of a chinese B indexing head clone, not a
> > > > big job but hard to do if its being driven under cutting loads
> > > > as in making spiral or hypoid gears.  I have another 100/1 worm
> > > > drive gearbox with a 3NM 3 phase motor on it that will get used
> > > > there if this plastic isn't up to that job. But I've been
> > > > messing with this instead of makeing the shaft couplings that
> > > > will take. Making 3 of this drive cuz the first 2 will
> > > > eventually be connecting the stellarium program to my now
> > > > elderly Meade DS-10 telescope, a 10" Newtonian design.  That
> > > > will take another rpi4 and some interfacing.
> > > >
> > > > Taking inventory, I still need a bag of 4mm nuts, and a smaller
> > > > bag of 4mm square nuts for the bearing carriers.  And suitable
> > > > grease, all of which seem to be of Chinese only source, and
> > > > another 6 weeks away.
> > > >
> > > > Stay well and safe Grumpy. From one grumpy, long retired old
> > > > fart to another.
> > > >
> > > > Cheers, Gene Heskett
> > >
> > > it sounds very cool
> >
> > I thought so too, but now I'm trapped. Dogone stuff is contagious :)
> >
> > > post a link to the thingiverse files
> >
> > Its already been posted to this list 3 times.
> >
> > > you should put up some pics of what you've got so far
> > > a pictorial cronical of your journey
> > > even the bad stuf is a lesson for us beginners
> >
> > What I intend to do is going to be more like a tut on how to take a
> > poorly designed but decent idea to the point of actually haveing
> > some of the advantages of the $1k dollar versions except their
> > longer life. In particular, how to make minor adjustments that will
> > make it work 10x longer.  Thats the general idea anyhow.  The long
> > life part is obviously TBD. Waiting before too much longer on some
> > M4 sq nuts. Ebay has exactly none. Might have to make them, and 4mm
> > is getting a bit teeny.
> >
> > Take care now.
> >
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > If we desire respect for the law, we must first make the law
> > respectable. - Louis D. Brandeis
> > Genes Web page 
> >
> >
> > ___
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> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Greg Bernard]

McMaster-Carr has 4 mm square nuts in stock.

On Wed, Aug 12, 2020, 8:39 PM Gene Heskett  wrote:

> On Wednesday 12 August 2020 15:55:39 grumpy--- via Emc-users wrote:
>
> > On Wed, 12 Aug 2020, Gene Heskett wrote:
> > > On Wednesday 12 August 2020 12:45:14 grumpy--- via Emc-users wrote:
> > >> gene, how is this project come'n
> > >> i keep look'n for pictures on your web site
> > >
> > > That will happen eventually but progress was slow when I started out
> > > with a printer that was totally uncalibrated OOTB. So once I got
> > > that figured out, the extruder was only feeding about 13mm of
> > > plastic for a 100mm feed. Then it was make flexgears creeping up on
> > > the right size to actually fit in the main bearing, you have to make
> > > it at least 3 red hairs small because the printer bleeds that much.
> > > So about 8 of them later, I finally have 3 that fit.  Then the size
> > > of the internal spline is too large for that sized gear, and I just
> > > now took the 2nd good one off the printer and may make the last one
> > > at another .05 less on the printers xy scales as there is still
> > > 15-20 thou of clearance between the teeth at maximum pullin on the
> > > sides of the bearing carrier. That will be added to by the fact that
> > > the bearing carrier is carrying 6 bearings in groups of 3. So I just
> > > reduced the scale to 79.85 from 79.9 as I believe there is room yet
> > > to tighten that up another few thou.  The closer that is, the less
> > > actual flexing the flexgear has to do and it won't fatigue and break
> > > so quick.
> > >
> > > I have already made some bearing carriers, but may have stretched
> > > them too much before I found the flexgears were too big for the
> > > bearings.  So that fit has not been pronounced as good yet.
> > >
> > > The idea then is to scale the bearing carrier for a teeny bit of
> > > overpush, flexing the houseing and circular spline a thou or 4 for a
> > > break-in wear clearance, keeping it backlash free a bit longer.
> > >
> > > The third one, if it has the cajones for the job, will be turning
> > > the worm of a chinese B indexing head clone, not a big job but
> > > hard to do if its being driven under cutting loads as in making
> > > spiral or hypoid gears.  I have another 100/1 worm drive gearbox
> > > with a 3NM 3 phase motor on it that will get used there if this
> > > plastic isn't up to that job. But I've been messing with this
> > > instead of makeing the shaft couplings that will take. Making 3 of
> > > this drive cuz the first 2 will eventually be connecting the
> > > stellarium program to my now elderly Meade DS-10 telescope, a 10"
> > > Newtonian design.  That will take another rpi4 and some interfacing.
> > >
> > > Taking inventory, I still need a bag of 4mm nuts, and a smaller bag
> > > of 4mm square nuts for the bearing carriers.  And suitable grease,
> > > all of which seem to be of Chinese only source, and another 6 weeks
> > > away.
> > >
> > > Stay well and safe Grumpy. From one grumpy, long retired old fart to
> > > another.
> > >
> > > Cheers, Gene Heskett
> >
> > it sounds very cool
>
> I thought so too, but now I'm trapped. Dogone stuff is contagious :)
>
> > post a link to the thingiverse files
>
> Its already been posted to this list 3 times.
>
> > you should put up some pics of what you've got so far
> > a pictorial cronical of your journey
> > even the bad stuf is a lesson for us beginners
>
> What I intend to do is going to be more like a tut on how to take a
> poorly designed but decent idea to the point of actually haveing some of
> the advantages of the $1k dollar versions except their longer life. In
> particular, how to make minor adjustments that will make it work 10x
> longer.  Thats the general idea anyhow.  The long life part is obviously
> TBD. Waiting before too much longer on some M4 sq nuts. Ebay has exactly
> none. Might have to make them, and 4mm is getting a bit teeny.
>
> Take care now.
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
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>

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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Wednesday 12 August 2020 15:55:39 grumpy--- via Emc-users wrote:

> On Wed, 12 Aug 2020, Gene Heskett wrote:
> > On Wednesday 12 August 2020 12:45:14 grumpy--- via Emc-users wrote:
> >> gene, how is this project come'n
> >> i keep look'n for pictures on your web site
> >
> > That will happen eventually but progress was slow when I started out
> > with a printer that was totally uncalibrated OOTB. So once I got
> > that figured out, the extruder was only feeding about 13mm of
> > plastic for a 100mm feed. Then it was make flexgears creeping up on
> > the right size to actually fit in the main bearing, you have to make
> > it at least 3 red hairs small because the printer bleeds that much. 
> > So about 8 of them later, I finally have 3 that fit.  Then the size
> > of the internal spline is too large for that sized gear, and I just
> > now took the 2nd good one off the printer and may make the last one
> > at another .05 less on the printers xy scales as there is still
> > 15-20 thou of clearance between the teeth at maximum pullin on the
> > sides of the bearing carrier. That will be added to by the fact that
> > the bearing carrier is carrying 6 bearings in groups of 3. So I just
> > reduced the scale to 79.85 from 79.9 as I believe there is room yet
> > to tighten that up another few thou.  The closer that is, the less
> > actual flexing the flexgear has to do and it won't fatigue and break
> > so quick.
> >
> > I have already made some bearing carriers, but may have stretched
> > them too much before I found the flexgears were too big for the
> > bearings.  So that fit has not been pronounced as good yet.
> >
> > The idea then is to scale the bearing carrier for a teeny bit of
> > overpush, flexing the houseing and circular spline a thou or 4 for a
> > break-in wear clearance, keeping it backlash free a bit longer.
> >
> > The third one, if it has the cajones for the job, will be turning
> > the worm of a chinese B indexing head clone, not a big job but
> > hard to do if its being driven under cutting loads as in making
> > spiral or hypoid gears.  I have another 100/1 worm drive gearbox
> > with a 3NM 3 phase motor on it that will get used there if this
> > plastic isn't up to that job. But I've been messing with this
> > instead of makeing the shaft couplings that will take. Making 3 of
> > this drive cuz the first 2 will eventually be connecting the
> > stellarium program to my now elderly Meade DS-10 telescope, a 10"
> > Newtonian design.  That will take another rpi4 and some interfacing.
> >
> > Taking inventory, I still need a bag of 4mm nuts, and a smaller bag
> > of 4mm square nuts for the bearing carriers.  And suitable grease,
> > all of which seem to be of Chinese only source, and another 6 weeks
> > away.
> >
> > Stay well and safe Grumpy. From one grumpy, long retired old fart to
> > another.
> >
> > Cheers, Gene Heskett
>
> it sounds very cool

I thought so too, but now I'm trapped. Dogone stuff is contagious :)

> post a link to the thingiverse files

Its already been posted to this list 3 times.

> you should put up some pics of what you've got so far
> a pictorial cronical of your journey
> even the bad stuf is a lesson for us beginners

What I intend to do is going to be more like a tut on how to take a 
poorly designed but decent idea to the point of actually haveing some of 
the advantages of the $1k dollar versions except their longer life. In 
particular, how to make minor adjustments that will make it work 10x 
longer.  Thats the general idea anyhow.  The long life part is obviously 
TBD. Waiting before too much longer on some M4 sq nuts. Ebay has exactly 
none. Might have to make them, and 4mm is getting a bit teeny.

Take care now.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[grumpy--- via Emc-users]

On Wed, 12 Aug 2020, Gene Heskett wrote:


On Wednesday 12 August 2020 12:45:14 grumpy--- via Emc-users wrote:


gene, how is this project come'n
i keep look'n for pictures on your web site


That will happen eventually but progress was slow when I started out with
a printer that was totally uncalibrated OOTB. So once I got that figured
out, the extruder was only feeding about 13mm of plastic for a 100mm
feed. Then it was make flexgears creeping up on the right size to
actually fit in the main bearing, you have to make it at least 3 red
hairs small because the printer bleeds that much.  So about 8 of them
later, I finally have 3 that fit.  Then the size of the internal spline
is too large for that sized gear, and I just now took the 2nd good one
off the printer and may make the last one at another .05 less on the
printers xy scales as there is still 15-20 thou of clearance between the
teeth at maximum pullin on the sides of the bearing carrier. That will
be added to by the fact that the bearing carrier is carrying 6 bearings
in groups of 3. So I just reduced the scale to 79.85 from 79.9 as I
believe there is room yet to tighten that up another few thou.  The
closer that is, the less actual flexing the flexgear has to do and it
won't fatigue and break so quick.

I have already made some bearing carriers, but may have stretched them
too much before I found the flexgears were too big for the bearings.  So
that fit has not been pronounced as good yet.

The idea then is to scale the bearing carrier for a teeny bit of
overpush, flexing the houseing and circular spline a thou or 4 for a
break-in wear clearance, keeping it backlash free a bit longer.

The third one, if it has the cajones for the job, will be turning the
worm of a chinese B indexing head clone, not a big job but hard to
do if its being driven under cutting loads as in making spiral or hypoid
gears.  I have another 100/1 worm drive gearbox with a 3NM 3 phase motor
on it that will get used there if this plastic isn't up to that job. But
I've been messing with this instead of makeing the shaft couplings that
will take. Making 3 of this drive cuz the first 2 will eventually be
connecting the stellarium program to my now elderly Meade DS-10
telescope, a 10" Newtonian design.  That will take another rpi4 and some
interfacing.

Taking inventory, I still need a bag of 4mm nuts, and a smaller bag of
4mm square nuts for the bearing carriers.  And suitable grease, all of
which seem to be of Chinese only source, and another 6 weeks away.

Stay well and safe Grumpy. From one grumpy, long retired old fart to
another.

Cheers, Gene Heskett


it sounds very cool
post a link to the thingiverse files
you should put up some pics of what you've got so far
a pictorial cronical of your journey
even the bad stuf is a lesson for us beginners


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Wednesday 12 August 2020 12:45:14 grumpy--- via Emc-users wrote:

> gene, how is this project come'n
> i keep look'n for pictures on your web site
>
That will happen eventually but progress was slow when I started out with 
a printer that was totally uncalibrated OOTB. So once I got that figured 
out, the extruder was only feeding about 13mm of plastic for a 100mm 
feed. Then it was make flexgears creeping up on the right size to 
actually fit in the main bearing, you have to make it at least 3 red 
hairs small because the printer bleeds that much.  So about 8 of them 
later, I finally have 3 that fit.  Then the size of the internal spline 
is too large for that sized gear, and I just now took the 2nd good one 
off the printer and may make the last one at another .05 less on the 
printers xy scales as there is still 15-20 thou of clearance between the 
teeth at maximum pullin on the sides of the bearing carrier. That will 
be added to by the fact that the bearing carrier is carrying 6 bearings 
in groups of 3. So I just reduced the scale to 79.85 from 79.9 as I 
believe there is room yet to tighten that up another few thou.  The 
closer that is, the less actual flexing the flexgear has to do and it 
won't fatigue and break so quick.

I have already made some bearing carriers, but may have stretched them 
too much before I found the flexgears were too big for the bearings.  So 
that fit has not been pronounced as good yet.

The idea then is to scale the bearing carrier for a teeny bit of 
overpush, flexing the houseing and circular spline a thou or 4 for a 
break-in wear clearance, keeping it backlash free a bit longer.

The third one, if it has the cajones for the job, will be turning the 
worm of a chinese B indexing head clone, not a big job but hard to 
do if its being driven under cutting loads as in making spiral or hypoid 
gears.  I have another 100/1 worm drive gearbox with a 3NM 3 phase motor 
on it that will get used there if this plastic isn't up to that job. But 
I've been messing with this instead of makeing the shaft couplings that 
will take. Making 3 of this drive cuz the first 2 will eventually be 
connecting the stellarium program to my now elderly Meade DS-10 
telescope, a 10" Newtonian design.  That will take another rpi4 and some 
interfacing.

Taking inventory, I still need a bag of 4mm nuts, and a smaller bag of 
4mm square nuts for the bearing carriers.  And suitable grease, all of 
which seem to be of Chinese only source, and another 6 weeks away. 

Stay well and safe Grumpy. From one grumpy, long retired old fart to 
another.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[grumpy--- via Emc-users]

gene, how is this project come'n
i keep look'n for pictures on your web site


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Monday 20 July 2020 10:08:16 Martin Dobbins wrote:

> >The zip contains a .step file. What does linux use to render/view
> > that? That file does contain the bearing part numbers, so that
> > helps, if my print is rendering the correct size.
>
> Freecad will open .step files.
>
> Martin
>
Means I have to cmake it. git is cloning the current src.

Thanks Martin.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Martin Dobbins]

>The zip contains a .step file. What does linux use to render/view that?
>That file does contain the bearing part numbers, so that helps, if my
>print is rendering the correct size.

Freecad will open .step files.

Martin




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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[andy pugh]

On Mon, 20 Jul 2020 at 12:20, Gene Heskett  wrote:

> > Layer-by-layer lets you see that. Most Thingiverse files suggest a
> > print direction and support options.
>
> An option I haven't found yet because the instant you do anything to the
> preview, it erases it presumably because the gcode is invalidated.

Prepare in the Prepare tab, then slice, then switch to preview and you
should see what will be printed.
The sliders in the right of the screen control the top and bottom
layers that are rendered.

> And cura's ability to monitor seems limited to tracking the two temps,
> everything else is blanked.

If you set it up right it will display a web-cam image there.
(Probably only with Octoprint with the Ender3)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[andy pugh]

On Mon, 20 Jul 2020 at 10:40, Gene Heskett  wrote:

> Am I supposed to be able to write the cura output gcode file to the
> printers u-sd card while its printing a differennt file?

I wouldn't expect so.



-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Monday 20 July 2020 07:04:21 andy pugh wrote:

> On Mon, 20 Jul 2020 at 11:50, Gene Heskett  
wrote:
> > > Those two inspection points are before the STL is created and
> > > after it has been used. (the Cura preview is a G-code preview)
> >
> > I've never seen video on the preview tab.
>
> I have no idea what you mean.
>
> What I mean is, in the preview tab, move the sliders so that you see a
> single layer, then zoom right in and see what the tooth shape looks
> like.
>
> > For some reason these stl files are all stood on edge.  But face
> > down puts the drive hub up in the air, so I've no clue what cura
> > will do for support structure.  Need an xray view of preview.
>
> Layer-by-layer lets you see that. Most Thingiverse viles suggest a
> print direction and support options.

An option I haven't found yet because the instant you do anything to the 
preview, it erases it presumably because the gcode is invalidated.

And cura's ability to monitor seems limited to tracking the two temps, 
everything else is blanked.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[andy pugh]

On Mon, 20 Jul 2020 at 11:50, Gene Heskett  wrote:

> > Those two inspection points are before the STL is created and after it
> > has been used. (the Cura preview is a G-code preview)
>
> I've never seen video on the preview tab.

I have no idea what you mean.

What I mean is, in the preview tab, move the sliders so that you see a
single layer, then zoom right in and see what the tooth shape looks
like.

> For some reason these stl files are all stood on edge.  But face down
> puts the drive hub up in the air, so I've no clue what cura will do for
> support structure.  Need an xray view of preview.

Layer-by-layer lets you see that. Most Thingiverse viles suggest a
print direction and support options.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Monday 20 July 2020 05:49:19 andy pugh wrote:

> On Mon, 20 Jul 2020 at 10:40, Gene Heskett  
wrote:
> > Some, but at much higher resolutions than what is being laid down in
> > plastic. My point is that .stl's obtained from non-openscad src's,
> > are reproduced much more accurately. Openscad's tooth profile for an
> > XL pulley is good. Any smaller teeth dissolves into a 20% fill with
> > almost zero resemblance to the tooth you can see in cura.
>
> That doesn't make any sense. If the model looks good in OpenSCAD and
> the G-code looks good in Cura then there is no way that it can be
> OpenSCADs fault.
Doesn't make sense to me either, but thats what seems to happen.

> Those two inspection points are before the STL is created and after it
> has been used. (the Cura preview is a G-code preview)

I've never seen video on the preview tab. Until now.
I just plugged the cable in and when I started cura, it paused the 
printer and parked it, so I'm seeing if resume works from its own 
control now.  Looks like it worked. I've loaded the wave gear, and 
flipped it open face down then sliced it. 17 hrs 42 minutes render time.
For some reason these stl files are all stood on edge.  But face down 
puts the drive hub up in the air, so I've no clue what cura will do for 
support structure.  Need an xray view of preview. Maybe shoulda put bolt 
face down, supports would be on back side and more easily removable.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[andy pugh]

On Mon, 20 Jul 2020 at 10:40, Gene Heskett  wrote:

> Some, but at much higher resolutions than what is being laid down in
> plastic. My point is that .stl's obtained from non-openscad src's, are
> reproduced much more accurately. Openscad's tooth profile for an XL
> pulley is good. Any smaller teeth dissolves into a 20% fill with almost
> zero resemblance to the tooth you can see in cura.

That doesn't make any sense. If the model looks good in OpenSCAD and
the G-code looks good in Cura then there is no way that it can be
OpenSCADs fault.
Those two inspection points are before the STL is created and after it
has been used. (the Cura preview is a G-code preview)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Monday 20 July 2020 04:15:59 andy pugh wrote:

> On Mon, 20 Jul 2020 at 01:01, Gene Heskett  
wrote:
> > And I can say without fear of contradiction the openscad IS the
> > problem,
>
> Or your application of OpenSCAD is at fault?
>
> Have you tried looking closely at the layer preview in Cura? Does that
> show facets?

Some, but at much higher resolutions than what is being laid down in 
plastic. My point is that .stl's obtained from non-openscad src's, are 
reproduced much more accurately. Openscad's tooth profile for an XL 
pulley is good. Any smaller teeth dissolves into a 20% fill with almost 
zero resemblance to the tooth you can see in cura. 

> You can experiment with STL resolution and slice preview in Cura while
> the printer is busy making parts.

Am I supposed to be able to write the cura output gcode file to the 
printers u-sd card while its printing a differennt file? That would be 
handy, replacing the sneakernet I'm doing now.

I have a usb cable ran, and I can see a hint of what its doing but 
nowhere near what I can see on its own screen. I've not been able to see 
a dir list from the card. I just took the first circular gear off, and 
started another copy, took around 13 hours for the first gear. Its 
stamped '015 on its top surface. As near as I can count, its a 42/1 
drive if tooth count / 2 is how you do it..

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[andy pugh]

On Mon, 20 Jul 2020 at 01:01, Gene Heskett  wrote:

> And I can say without fear of contradiction the openscad IS the problem,

Or your application of OpenSCAD is at fault?

Have you tried looking closely at the layer preview in Cura? Does that
show facets?
You can experiment with STL resolution and slice preview in Cura while
the printer is busy making parts.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 19 July 2020 20:30:35 John Dammeyer wrote:

> This may well be a dumb question Gene, but given you have the machine
> shop and CNC couldn't you make the gears etc yourself out of metal?
> John
>
Thats why I bought a BS-1, John but I'm only about $250 into motorizing 
it yet, waiting on a set of reamers ATM so I can make gearbox couplings.

> > -Original Message-
> > From: Gene Heskett [mailto:ghesk...@shentel.net]
> > Sent: July-19-20 4:59 PM
> > To: 'Enhanced Machine Controller (EMC)'
> > Subject: [Emc-users] found a harmonic drive set of .stl's on
> > thingiverse
> >
> > Greetings all;
> >
> > And I can say without fear of contradiction the openscad IS the
> > problem,
> >
> > I am current about 2mm up of a print of the outside gear of the
> > drive, and the teeth are 100% filled and very well formed so far,
> > its the best rendering I've seen on the build bed yet, so much
> > better than what openscad generates I thought my machine had been
> > swapped for a well adjusted one in the night last night. I think
> > I'll make about 3 of everything so I'll have 2 drives and a spares
> > kit.
> >
> > Biggest  problem is the 12+ hour renderiing time per piece pf this
> > first piece, and there are 2 pieces bigger yet than this one.  Now I
> > can see why some folks have a whole room full of printers. I'll be
> > two weeks making parts for three drives.
> >
> > Hopefully I can put it together correctly, there are no text files
> > and I haven't the foggiest what bearings I'll need, or what brand of
> > grease.
> >
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > If we desire respect for the law, we must first make the law
> > respectable. - Louis D. Brandeis
> > Genes Web page 
> >
> >
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>
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

On Sunday 19 July 2020 19:58:44 Gene Heskett wrote:

> Greetings all;
>
> And I can say without fear of contradiction the openscad IS the
> problem,
>
> I am current about 2mm up of a print of the outside gear of the drive,
> and the teeth are 100% filled and very well formed so far, its the
> best rendering I've seen on the build bed yet, so much better than
> what openscad generates I thought my machine had been swapped for a
> well adjusted one in the night last night. I think I'll make about 3
> of everything so I'll have 2 drives and a spares kit.
>
> Biggest  problem is the 12+ hour renderiing time per piece pf this
> first piece, and there are 2 pieces bigger yet than this one.  Now I
> can see why some folks have a whole room full of printers. I'll be two
> weeks making parts for three drives.
>
> Hopefully I can put it together correctly, there are no text files and
> I haven't the foggiest what bearings I'll need, or what brand of
> grease.
>
> Cheers, Gene Heskett

The zip contains a .step file. What does linux use to render/view that?
That file does contain the bearing part numbers, so that helps, if my 
print is rendering the correct size.

Thanks all.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[John Dammeyer]

This may well be a dumb question Gene, but given you have the machine shop and 
CNC couldn't you make the gears etc yourself out of metal?
John

> -Original Message-
> From: Gene Heskett [mailto:ghesk...@shentel.net]
> Sent: July-19-20 4:59 PM
> To: 'Enhanced Machine Controller (EMC)'
> Subject: [Emc-users] found a harmonic drive set of .stl's on thingiverse
> 
> Greetings all;
> 
> And I can say without fear of contradiction the openscad IS the problem,
> 
> I am current about 2mm up of a print of the outside gear of the drive,
> and the teeth are 100% filled and very well formed so far, its the best
> rendering I've seen on the build bed yet, so much better than what
> openscad generates I thought my machine had been swapped for a well
> adjusted one in the night last night. I think I'll make about 3 of
> everything so I'll have 2 drives and a spares kit.
> 
> Biggest  problem is the 12+ hour renderiing time per piece pf this first
> piece, and there are 2 pieces bigger yet than this one.  Now I can see
> why some folks have a whole room full of printers. I'll be two weeks
> making parts for three drives.
> 
> Hopefully I can put it together correctly, there are no text files and I
> haven't the foggiest what bearings I'll need, or what brand of grease.
> 
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
> 
> 
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users



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[Emc-users] found a harmonic drive set of .stl's on thingiverse

[Gene Heskett]

Greetings all;

And I can say without fear of contradiction the openscad IS the problem,

I am current about 2mm up of a print of the outside gear of the drive, 
and the teeth are 100% filled and very well formed so far, its the best 
rendering I've seen on the build bed yet, so much better than what 
openscad generates I thought my machine had been swapped for a well 
adjusted one in the night last night. I think I'll make about 3 of 
everything so I'll have 2 drives and a spares kit.

Biggest  problem is the 12+ hour renderiing time per piece pf this first 
piece, and there are 2 pieces bigger yet than this one.  Now I can see 
why some folks have a whole room full of printers. I'll be two weeks 
making parts for three drives.

Hopefully I can put it together correctly, there are no text files and I 
haven't the foggiest what bearings I'll need, or what brand of grease. 

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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