Re: [Emc-users] New zero backlash gearbox

[Gene Heskett]

On Thursday 26 August 2021 22:58:10 Leonardo Marsaglia wrote:

> > But I still think the loose belt is a better idea. But get rid of
> > the separate and expensive ball bearings and make the armature
> > itself eccentric, wrapping it in a dual row, printed in plastic
> > bearing using crosman bb's for balls is working moderately well for
> > me.  And it will be strongest when the splines are worn to fit each
> > other. What I am fine tuning right now, and may have to resort to a
> > smaller nozzle to print it, is a new preloaded fit that when broke
> > in, still has zero backlash. But one of them has now been running on
> > my kitchen counter for a month at about 20 rpm output, 600 at the
> > motor, with no noise and no breakage, with a 1NM motor turning it.
> > But it can't be done in PLA, must have the more flexible PETG. And
> > that eliminates any printer not using at least an E3D V6 or better
> > hot end, I now have 5 printers tossed in the corner, which claimed
> > to be able to use PETG. Once maybe, but not a full spool of it.
>
> Hi gene, I hope you're doing well.
>
Other than a PSA out of sight, par for my age, I think I am doing well 
for 86 yo. Neighbors see me working in the yard and claim I'm lying when 
I say 86. Right now I'm putting in vinyl fence, so I'm pulling postholes 
for the older stuff. Thats an8 foot 4x4 with a 2 foot plug of cement on 
the bottom of it, and its about all my 18 horse husky rider wants to 
pull to get it somewhere near the "take it to the landfill" trailer. And 
I've 3 of those to pull yet. Broke my 20 yo handiman jack loosening that 
one, bought a long ram hydraulic and a bucket of chain to finish that 
but that jack is a lot slower than the handiman, so its about 2/3rd 
fixed now. Need to make a 5/8" pin thru the top hole to attach some guy 
cables to from a 3 foot 2x6 screwed to its foot. Tomorrow if the weather 
co-operates.

> What problems did you have with your printers and PETG? Have you tried
> the Ender 5 PRO?

Thats one of the printers sitting in the corner pile. It sorta worked, 
but the plastic extruder broke and I put one of crealities all metal 
ones on it, an exact copy of the plastic one but all metal, but after 
I'd put it back together, it would only drive the build plate down. I 
sent creality a message but never got a reply.

So then I believed the propaganda and bought a CR10-S Pro V2.  Which 
started leaking between the heat break and the sink on obout the third 
print.  So then I bought a BIQU HX which has the latest H2 printhead, 
and bought another H2 thinking of putting it onthe CR10 but while the 
BIQU has excellent firmware and a 7" touch screen, it too rejected a 
steady diet of PETG, leaking from above the hot block, and its a bear to 
get apart and worse to put back together, so combined with a poorly 
designed adaptors because the Pro V2 has a totally differnt carraige, so 
it never got put on. Then I spotted the Haldis version of an E3D v6 and 
some mounting brackets for that, designed and printed an adaptor to put 
a sherpa ejector on top of the haldis for a direct drive. All this after 
buying an $800 prusa as a kit whch does have an E3D V6 hot end hidden in 
the plastic the Prusa head is made of.  And even the Prusa is high 
maintenance due to the nozzle being self loosening if not cranked down 
hard enough to kill an Olsen Rudy. About every other day. And you have 
to take the part fan and nozzle off to get a wrench on the hot block, 
and since the recommended temp to tighten the nozzle is 290C, you've got 
about 10 seconds to tighten it before the wrench burns your hand. 

But I may have now blown something in the CR10's filament detector 
circuit, there was a blue led on an interface board at the left end of 
the X bar, which went out forever when I plugged the sensor back in, and 
now creality is refusing to give me a filament sensor wiring diagram.

I wouldn't mind putting a few shekels into the ender 5 or the CR10, but 
if creatilty refuses to supply that info, then the ender 7 goes off my 
wish list. Even a $2000 Dremel cannot do PETG, I sent it back because a 
lot of other stuff it had didn't work, they put a nozzle in it and sent 
it back. So just to get that lesson out of the house I gave it to my 
stepson. He's feeding it PLA and having a ball, but without doing PETG 
as a daily diet, it was just a headache I had to walk around.

Also. the ender 5 Pro wasn't square, so circles printed like a leaning 
eccentric. About 1/8" trapezoidal.  Loosening and retorqueing all the 
bolts in the top frame didn't help.

> I have one of those and had moderate success with 
> PETG (didn't worked with it too much) but I use it mostly with ABS to
> create casting patterns because it is easy to sand and smooth with
> acetone. The extruder is not direct but it's all metal and the hotend
> reaches 260º. I just changed the firmware to the latest Marlin and
> activated the manual mesh levelling to get better adhesion. Also I
> made a quick 

Re: [Emc-users] New zero backlash gearbox

[Leonardo Marsaglia]

>
> But I still think the loose belt is a better idea. But get rid of the
> separate and expensive ball bearings and make the armature itself
> eccentric, wrapping it in a dual row, printed in plastic bearing using
> crosman bb's for balls is working moderately well for me.  And it will
> be strongest when the splines are worn to fit each other. What I am fine
> tuning right now, and may have to resort to a smaller nozzle to print
> it, is a new preloaded fit that when broke in, still has zero backlash.
> But one of them has now been running on my kitchen counter for a month
> at about 20 rpm output, 600 at the motor, with no noise and no breakage,
> with a 1NM motor turning it. But it can't be done in PLA, must have the
> more flexible PETG. And that eliminates any printer not using at least
> an E3D V6 or better hot end, I now have 5 printers tossed in the corner,
> which claimed to be able to use PETG. Once maybe, but not a full spool
> of it.
>

Hi gene, I hope you're doing well.

What problems did you have with your printers and PETG? Have you tried the
Ender 5 PRO? I have one of those and had moderate success with PETG (didn't
worked with it too much) but I use it mostly with ABS to create casting
patterns because it is easy to sand and smooth with acetone. The extruder
is not direct but it's all metal and the hotend reaches 260º. I just
changed the firmware to the latest Marlin and activated the manual mesh
levelling to get better adhesion. Also I made a quick enclosure for it with
polycarbonate and put a resistor inside to heat the chamber to 60º C. I'm
priting ABS with a 1 mm nozzle pretty well. Tried nylon and had some
success with small parts but horrible warping with large parts (also at 60º
C on the chamber).

El jue, 26 ago 2021 a las 23:35, Gene Heskett ()
escribió:

> On Thursday 26 August 2021 17:57:09 Ralph Stirling wrote:
>
> > This might inspire some of you.
> >
> > https://www.wittenstein-us.com/zero-backlash-galaxie-gearbox/
> >
> > -- Ralph
>
> That looks like an excedrin headache to try and print.
>
> IMO, this is designed to get around any patents that might still exist,
> and would need far more precise a make and high priced steels.
>
> But I still think the loose belt is a better idea. But get rid of the
> separate and expensive ball bearings and make the armature itself
> eccentric, wrapping it in a dual row, printed in plastic bearing using
> crosman bb's for balls is working moderately well for me.  And it will
> be strongest when the splines are worn to fit each other. What I am fine
> tuning right now, and may have to resort to a smaller nozzle to print
> it, is a new preloaded fit that when broke in, still has zero backlash.
> But one of them has now been running on my kitchen counter for a month
> at about 20 rpm output, 600 at the motor, with no noise and no breakage,
> with a 1NM motor turning it. But it can't be done in PLA, must have the
> more flexible PETG. And that eliminates any printer not using at least
> an E3D V6 or better hot end, I now have 5 printers tossed in the corner,
> which claimed to be able to use PETG. Once maybe, but not a full spool
> of it.
>
> >
> > ___
> > 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 
>
>
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> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>

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Re: [Emc-users] New zero backlash gearbox

[Gene Heskett]

On Thursday 26 August 2021 17:57:09 Ralph Stirling wrote:

> This might inspire some of you.
>
> https://www.wittenstein-us.com/zero-backlash-galaxie-gearbox/
>
> -- Ralph

That looks like an excedrin headache to try and print.

IMO, this is designed to get around any patents that might still exist, 
and would need far more precise a make and high priced steels.

But I still think the loose belt is a better idea. But get rid of the 
separate and expensive ball bearings and make the armature itself 
eccentric, wrapping it in a dual row, printed in plastic bearing using 
crosman bb's for balls is working moderately well for me.  And it will 
be strongest when the splines are worn to fit each other. What I am fine 
tuning right now, and may have to resort to a smaller nozzle to print 
it, is a new preloaded fit that when broke in, still has zero backlash. 
But one of them has now been running on my kitchen counter for a month 
at about 20 rpm output, 600 at the motor, with no noise and no breakage, 
with a 1NM motor turning it. But it can't be done in PLA, must have the 
more flexible PETG. And that eliminates any printer not using at least 
an E3D V6 or better hot end, I now have 5 printers tossed in the corner, 
which claimed to be able to use PETG. Once maybe, but not a full spool 
of it.

>
> ___
> 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 


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Re: [Emc-users] New zero backlash gearbox

[Leonardo Marsaglia]

Really nice. Looks similar to a harmonic drive but more complicated. It
would be awesome to see what are the advantages of these over harmonic
drives.

El jue, 26 ago 2021 a las 19:00, Ralph Stirling (<
ralph.stirl...@wallawalla.edu>) escribió:

> This might inspire some of you.
>
> https://www.wittenstein-us.com/zero-backlash-galaxie-gearbox/
>
> -- Ralph
>
>
>
> ___
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> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>

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[Emc-users] New zero backlash gearbox

[Ralph Stirling]

This might inspire some of you.

https://www.wittenstein-us.com/zero-backlash-galaxie-gearbox/

-- Ralph



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Re: [Emc-users] jerk control

[Rob C]

how is everyone working out jerk / jolt?

on a stepper motor you have a defined step or micro step (distance)

so if your acceleration is say 3000mm/s/s. (plasma cutter)

and you are driving a 20T mod 1 rack and pinion with a 3:1 ratio drive,
with a 200 step per rev stepper motor on 10uSteps

the distance traveled per step is 0.01047197551 mm

at 3000mm/s/s, the time that it takes from zero to the first step is

sqroot ( 2x distance / acceleration) = 0.0026422182 seconds

the jerk / jolt is therefore (acceleration X time for first step) >>> 3000
X 0.0026422182 = 7.92 mm/s/s/s

without the 3:1 ratio drive reduction, the jolt or jerk is
 13.72 mm/s/s/s. (or 1.73x greater than without a 3:1 ratio drive

I used to have my same machine set up with a direct htd 5m 20T belt drive
(ie each microstep was 0.05mm), with the same acceleration, the jolt or
jerk was 17.32 mm/s/s/s. although the belts were rubber and no doubt
some compression of the teeth and movement in the belts took place

Firstly I am trying to check my math is correct?



On Thu, 26 Aug 2021, 09:44 andy pugh,  wrote:

> On Thu, 26 Aug 2021 at 00:34, Alexander Brock 
> wrote:
>
> > There is an elegant way to compute exact derivatives without computing
> > analytical derivatives by hand. Here is a nice introduction:
>
> Is that applicable to the LinuxCNC kinematics functions? (Which are
> kernel modules written in C).
>
> --
> 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] jerk control

[andy pugh]

On Thu, 26 Aug 2021 at 00:34, Alexander Brock  wrote:

> There is an elegant way to compute exact derivatives without computing
> analytical derivatives by hand. Here is a nice introduction:

Is that applicable to the LinuxCNC kinematics functions? (Which are
kernel modules written in C).

-- 
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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