Re: [Emc-users] I wonder if I can fix it?

[Stuart Stevenson]

Maybe a stratified heat treat would give you a flex area. Induction heat
treat would be able to do that.

On Thu, Jan 7, 2021, 3:51 AM Roland Jollivet 
wrote:

> On Thu, 7 Jan 2021 at 01:35, Gregg Eshelman via Emc-users <
> emc-users@lists.sourceforge.net> wrote:
>
> > I wonder if a replacement cup spline with an elastomeric part would work?
> > Make teeth that interlock at the side of the spline wall and the back
> > plate, with a thin filler of high durometer flexible urethane, bonded to
> > the metal with something like Smooth-On Ure-Bond II.
> > 
>
>
>
> One way to make the spline would be to sinter it. The steel powders are
> readily available.
> While the shape is readily attainable, I don't know how well sintered parts
> stand up to long term flexing..
>
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[Emc-users] I wonder if I can fix it?

[Roland Jollivet]

On Thu, 7 Jan 2021 at 01:35, Gregg Eshelman via Emc-users <
emc-users@lists.sourceforge.net> wrote:

> I wonder if a replacement cup spline with an elastomeric part would work?
> Make teeth that interlock at the side of the spline wall and the back
> plate, with a thin filler of high durometer flexible urethane, bonded to
> the metal with something like Smooth-On Ure-Bond II.
> 



One way to make the spline would be to sinter it. The steel powders are
readily available.
While the shape is readily attainable, I don't know how well sintered parts
stand up to long term flexing..

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Re: [Emc-users] I wonder if I can fix it?

[Gregg Eshelman via Emc-users]

You'd want the rollers to have teeth matching the interior ribbed shape of the 
spline.

On Wednesday, January 6, 2021, 7:42:54 AM MST, Todd Zuercher 
 wrote:  
 
 I wonder if instead of machined spines, the cup could be made from a sheet 
stamping with the splines simply crimped into the sheet.  (Although that 
wouldn't help Andy with making a homemade one.) 
  
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Re: [Emc-users] I wonder if I can fix it?

[andrew beck]

As someone else says.  Cycloidal gears look totally diy on a cnc mill

On Thu, Jan 7, 2021, 12:35 PM Gregg Eshelman via Emc-users <
emc-users@lists.sourceforge.net> wrote:

> I wonder if a replacement cup spline with an elastomeric part would work?
> Make teeth that interlock at the side of the spline wall and the back
> plate, with a thin filler of high durometer flexible urethane, bonded to
> the metal with something like Smooth-On Ure-Bond II.
>
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Re: [Emc-users] I wonder if I can fix it?

[Gregg Eshelman via Emc-users]

I wonder if a replacement cup spline with an elastomeric part would work? Make 
teeth that interlock at the side of the spline wall and the back plate, with a 
thin filler of high durometer flexible urethane, bonded to the metal with 
something like Smooth-On Ure-Bond II.

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Re: [Emc-users] I wonder if I can fix it?

[andy pugh]

On Wed, 6 Jan 2021 at 19:41, Roland Jollivet  wrote:
>
> I did a similar thing a while back, wanting to see if I could make a single
> stage gear-gear reducer.

I actually tried to use a design like yours in a commercial product, I
needed a really thin drive system. In my case I tried to prevent
rotation but allow oscillation with a flexure system. It was very much
a "partial success". Your Oldham coupling idea is probably better, but
uses thickness that I couldn't spare.

-- 
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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[Emc-users] I wonder if I can fix it?

[Roland Jollivet]

On Wed, 6 Jan 2021 at 17:22, andy pugh  wrote:

> On Wed, 6 Jan 2021 at 14:52, Ralph Stirling
>  wrote:
> >
> > Along those lines, could curved "teeth" like cycloidal reducers be used
> with a flex element?
>
> Here's something I designed earlier :-)
>
> https://youtu.be/VrvwlPxRhKU
>
>
I did a similar thing a while back, wanting to see if I could make a single
stage gear-gear reducer. Of course, at speed it becomes a wobbulator,
unlike the flex coupling being balanced.

I had the parts laser cut to check the meshing and the resolution came out
quite well. I can send a pic of the actual gears when I get back to the
workshop..
Here is a pic of the gears and a universal coupling I would use to take off
power.
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Re: [Emc-users] I wonder if I can fix it?

[andy pugh]

On Wed, 6 Jan 2021 at 14:52, Ralph Stirling
 wrote:
>
> Along those lines, could curved "teeth" like cycloidal reducers be used with 
> a flex element?

Here's something I designed earlier :-)

https://youtu.be/VrvwlPxRhKU


-- 
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] I wonder if I can fix it?

[Ralph Stirling]

Along those lines, could curved "teeth" like cycloidal reducers be used with a 
flex element?

-- Ralph

On Jan 6, 2021 6:41 AM, Todd Zuercher  wrote:
CAUTION: This email originated from outside the Walla Walla University email 
system.


I wonder if instead of machined spines, the cup could be made from a sheet 
stamping with the splines simply crimped into the sheet.  (Although that 
wouldn't help Andy with making a homemade one.)


-Original Message-
From: Roland Jollivet 
Sent: Wednesday, January 06, 2021 9:06 AM
To: Enhanced Machine Controller (EMC) 
Subject: [Emc-users] I wonder if I can fix it?

I've been pondering this for a while now, wondering if there's a design shape 
that has been missed.
In terms of a fresh design, things that could be done;
- increase the length of the cup
- put cutouts in strategic places
- use a cone rather than a cup
- make the cup in more than one piece (flexspline +CV bearing)



On Tue, 5 Jan 2021 at 19:28, andy pugh  wrote:

> I bought an FHA-17C actuator from eBay. It was cheaper than normal,
> for parts or not working.
> It clearly had the cables cut off, so I decided to gamble.
>
> It turns out that things were worse than I hoped.
>
> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fphotos.app.goo.gl%2Fp3SL2Bwv2b9yd5XJ9data=04%7C01%7Cralph.stirling%40wallawalla.edu%7C300a113beb3448eb99f508d8b25123c4%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C0%7C637455408864537060%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000sdata=hFqewdI6dh%2BA5nxd%2Fs0zJImaSjAIe7BojJ6x1h%2BqsRQ%3Dreserved=0
>
> I am seriously considering trying to make a new flexspline. I mean,
> how hard can it be?
>
> --
> 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] I wonder if I can fix it?

[Todd Zuercher]

I wonder if instead of machined spines, the cup could be made from a sheet 
stamping with the splines simply crimped into the sheet.  (Although that 
wouldn't help Andy with making a homemade one.) 


-Original Message-
From: Roland Jollivet  
Sent: Wednesday, January 06, 2021 9:06 AM
To: Enhanced Machine Controller (EMC) 
Subject: [Emc-users] I wonder if I can fix it?

I've been pondering this for a while now, wondering if there's a design shape 
that has been missed.
In terms of a fresh design, things that could be done;
- increase the length of the cup
- put cutouts in strategic places
- use a cone rather than a cup
- make the cup in more than one piece (flexspline +CV bearing)



On Tue, 5 Jan 2021 at 19:28, andy pugh  wrote:

> I bought an FHA-17C actuator from eBay. It was cheaper than normal, 
> for parts or not working.
> It clearly had the cables cut off, so I decided to gamble.
>
> It turns out that things were worse than I hoped.
>
> https://photos.app.goo.gl/p3SL2Bwv2b9yd5XJ9
>
> I am seriously considering trying to make a new flexspline. I mean, 
> how hard can it be?
>
> --
> 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
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>

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Re: [Emc-users] I wonder if I can fix it?

[andy pugh]

On Wed, 6 Jan 2021 at 14:09, Roland Jollivet  wrote:

> - make the cup in more than one piece (flexspline +CV bearing)

There is a variant design used in some of the HD systems that uses two
of the outer ring gears and a double-length cylindrical flexspline.
The outer rings have different numbers of teeth, one has the same
number as the flexspline, one has two more.
http://www.hds.co.jp/english/products/lineup/hd/01sr06_fb_2a/

(I actually have one, but have not thought of a use for it yet)

-- 
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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[Emc-users] I wonder if I can fix it?

[Roland Jollivet]

I've been pondering this for a while now, wondering if there's a design
shape that has been missed.
In terms of a fresh design, things that could be done;
- increase the length of the cup
- put cutouts in strategic places
- use a cone rather than a cup
- make the cup in more than one piece (flexspline +CV bearing)



On Tue, 5 Jan 2021 at 19:28, andy pugh  wrote:

> I bought an FHA-17C actuator from eBay. It was cheaper than normal,
> for parts or not working.
> It clearly had the cables cut off, so I decided to gamble.
>
> It turns out that things were worse than I hoped.
>
> https://photos.app.goo.gl/p3SL2Bwv2b9yd5XJ9
>
> I am seriously considering trying to make a new flexspline. I mean,
> how hard can it be?
>
> --
> 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
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>

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Re: [Emc-users] I wonder if I can fix it?

[Jon Elson]

On 01/05/2021 06:05 PM, John Dammeyer wrote:

Interesting.

One could do an experiment.  Cut a cup the size of the gear but without the 
teeth.  Then mount it and run an offset skateboard wheel inside it to flex it 
about the amount the gear would flex.  Count revolutions and let it go.  How 
many days, weeks etc before failure?

But, the teeth will cause stress concentrations, so the 
final design might fail MUCH, MUCH sooner once the teeth are 
there.


Jon


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Re: [Emc-users] I wonder if I can fix it?

[andy pugh]

On Wed, 6 Jan 2021 at 00:30, John Dammeyer  wrote:

> Are you able to CAD model the existing broken one or is it too far gone?

I think I can work it out from knowing where it belongs.

> I suspect the Hob will be the most work.

I think it might be a job for a single-lip cutter.

I would struggle to machine a hob hard enough to cut the appropriate material.

-- 
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] I wonder if I can fix it?

[John Dammeyer]

Andy,
Are you able to CAD model the existing broken one or is it too far gone?  

I suspect the Hob will be the most work.

John
 

> -Original Message-
> From: andy pugh [mailto:bodge...@gmail.com]
> Sent: January-05-21 4:18 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] I wonder if I can fix it?
> 
> On Wed, 6 Jan 2021 at 00:07, John Dammeyer  wrote:
> 
> > One could do an experiment.  Cut a cup the size of the gear but without the 
> > teeth.  Then mount it and run an offset skateboard
> wheel inside it to flex it about the amount the gear would flex.  Count 
> revolutions and let it go.  How many days, weeks etc before
> failure?
> 
> I could just use the wave generator.
> 
> But I suspect that it would last a lot longer without the teeth.
> 
> --
> 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] I wonder if I can fix it?

[andy pugh]

On Wed, 6 Jan 2021 at 00:07, John Dammeyer  wrote:

> One could do an experiment.  Cut a cup the size of the gear but without the 
> teeth.  Then mount it and run an offset skateboard wheel inside it to flex it 
> about the amount the gear would flex.  Count revolutions and let it go.  How 
> many days, weeks etc before failure?

I could just use the wave generator.

But I suspect that it would last a lot longer without the teeth.

-- 
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] I wonder if I can fix it?

[John Dammeyer]

Interesting.

One could do an experiment.  Cut a cup the size of the gear but without the 
teeth.  Then mount it and run an offset skateboard wheel inside it to flex it 
about the amount the gear would flex.  Count revolutions and let it go.  How 
many days, weeks etc before failure?

And while that is happening work on making a hob.

John


> -Original Message-
> From: andy pugh [mailto:bodge...@gmail.com]
> Sent: January-05-21 3:35 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] I wonder if I can fix it?
> 
> On Tue, 5 Jan 2021 at 23:05,  wrote:
> >
> > https://www.makeitfrom.com/compare/SAE-AISI-4140-SCM440-G41400-Cr-Mo-Steel/SAE-AISI-P20-T51620-Low-Carbon-Mould-
> Steel
> 
> Possibly a little more informative:
> http://harrisonspecialiststeels.co.uk/tool-steel/p20-mould-steel/
> 
> --
> 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] I wonder if I can fix it?

[andy pugh]

On Tue, 5 Jan 2021 at 23:05,  wrote:
>
> https://www.makeitfrom.com/compare/SAE-AISI-4140-SCM440-G41400-Cr-Mo-Steel/SAE-AISI-P20-T51620-Low-Carbon-Mould-Steel

Possibly a little more informative:
http://harrisonspecialiststeels.co.uk/tool-steel/p20-mould-steel/

-- 
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] I wonder if I can fix it?

[ken.strauss]

https://www.makeitfrom.com/compare/SAE-AISI-4140-SCM440-G41400-Cr-Mo-Steel/SAE-AISI-P20-T51620-Low-Carbon-Mould-Steel


-Original Message-
From: John Dammeyer  
Sent: January 5, 2021 5:57 PM
To: 'Enhanced Machine Controller (EMC)' 
Subject: Re: [Emc-users] I wonder if I can fix it?

> > After heat treating it would probably require some grinding or polishing 
> > unless you can cover it in a way that it won't oxidize.
> 
> I am wondering about using something like P20.
> 
> 
What is P20?
John

> --
> 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] I wonder if I can fix it?

[John Dammeyer]

> > After heat treating it would probably require some grinding or polishing 
> > unless you can cover it in a way that it won't oxidize.
> 
> I am wondering about using something like P20.
> 
> 
What is P20?
John

> --
> 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] I wonder if I can fix it?

[andy pugh]

On Tue, 5 Jan 2021 at 22:26, John Dammeyer  wrote:

> After heat treating it would probably require some grinding or polishing 
> unless you can cover it in a way that it won't oxidize.

I am wondering about using something like P20.


-- 
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] I wonder if I can fix it?

[John Dammeyer]

> From: andy pugh [mailto:bodge...@gmail.com]
> 
> On Tue, 5 Jan 2021 at 21:31, John Dammeyer  wrote:
> 
> > Turn the inside to a predefined diameter and press in a support hub that 
> > has a center hole that will be used for support.
> 
> That mirrors what I was thinking of doing, though as the part is only
> 50mm diameter there is probably no need to fabricate the blank.
> 
> --
> atp

I'd still start with much larger than 50mm and then bore the inside first to 
create the holder.  Even if you first turned the outside and milled the teeth 
you then have to hold it so it _won't_ flex as designed while you turn the 
inside to size.

You could fabricate a retaining ring that slips on just below the teeth and 
even over the finished teeth for the fixed steady.   And then bore out the 
inside.  

After heat treating it would probably require some grinding or polishing unless 
you can cover it in a way that it won't oxidize.

John




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Re: [Emc-users] I wonder if I can fix it?

[andy pugh]

On Tue, 5 Jan 2021 at 21:31, John Dammeyer  wrote:

> Turn the inside to a predefined diameter and press in a support hub that has 
> a center hole that will be used for support.

That mirrors what I was thinking of doing, though as the part is only
50mm diameter there is probably no need to fabricate the blank.

-- 
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] I wonder if I can fix it?

[Chris Albertson]

Quite a lot of the drive is still in perfect shape.   That flex cup part is
toast.

What you can do is try and 3D print a new flex cup but do NOT repeat the #1
mistake that almost everyone does.  They try and duplicate a metal design
but use plastic.  That approach is doomed to fail.  A plastic part will
have 10X greater volume of materials.  Rather than a "flex-CUP" try a
"flex-HOCKEY PUCK"   Maybe it looks like a metal disk with a ribbed tire on
it.

I read where Gene tried many times to print one of these,  that failed
because the designer thought he was designing with metal.  I really think a
nylon tire over some TPU over a rigid metal wheel might work.

The final result is not the same as metal part will always have a better
strength to volume ratio and better cooing and work at a higher speed.
 But maybe you can get 30% of the torque from a plastic replacement part.

I've been slowly making machine tool parts from PLA and the results are not
bad.  The trick is to NOT pretend that PLA is cast iron.

On Tue, Jan 5, 2021 at 9:28 AM andy pugh  wrote:

> I bought an FHA-17C actuator from eBay. It was cheaper than normal,
> for parts or not working.
> It clearly had the cables cut off, so I decided to gamble.
>
> It turns out that things were worse than I hoped.
>
> https://photos.app.goo.gl/p3SL2Bwv2b9yd5XJ9
>
> I am seriously considering trying to make a new flexspline. I mean,
> how hard can it be?
>
> --
> 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] I wonder if I can fix it?

[John Dammeyer]

Instead of carving away over 90% to make one I wonder it an outside of the box 
approach might work.  

Start with a piece of pipe stock close to the right size.  Turn bevels on the 
bottom edge and a disk to fit against the bottom.  

Weld in a disk at the bottom.  Heat treat and allow to cool to leave material 
soft as possible.

Turn the inside to a predefined diameter and press in a support hub that has a 
center hole that will be used for support.   (Possibly epoxy and a slightly 
looser fit for all but both ends? )Turn in the chuck and drill a center hole on 
the other end and face plus add the radius on the edge.

Mill the 4 or 5 lightening holes in the bottom and put it back in the lathe and 
in Andy's case hold it in the chuck since he can move that to his Harmonic 
Drive.  Hold the other end with a ball bearing center.  Or use the center at 
both ends and a drive dog.

Now turn the diameter continuing from the radius leaving the thicker outboard 
end for the tooth form.  Again in Andy's case transfer the chuck to the 
harmonic 4th axis.  

Install that Hob that he's always wanted to learn how to make and cut the 
teeth.  Heat the end result enough to soften the epoxy and press out the hub.  

If the dimensions are correct you have a soft hub that now needs 
hardening/tempering. 

Just an idea.
John

> -Original Message-
> From: andy pugh [mailto:bodge...@gmail.com]
> Sent: January-05-21 12:42 PM
> To: ra...@linwin.com; Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] I wonder if I can fix it?
> 
> On Tue, 5 Jan 2021 at 20:36, Rafael Skodlar  wrote:
> 
> > > I am seriously considering trying to make a new flexspline. I mean,
> > > how hard can it be?
> > >
> >
> > Based on what I know about harmonic drives, extremely hard.
> 
> Yes, I was being a little sarcastic. But if I don't expect to make a
> _good_ one, I think I can do it.
> 
> > https://www.harmonicdrive.net/technology
> >
> 
> Rather usefully that has a picture of the tooth shape.
> 
> --
> 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] I wonder if I can fix it?

[andy pugh]

On Tue, 5 Jan 2021 at 20:36, Rafael Skodlar  wrote:

> > I am seriously considering trying to make a new flexspline. I mean,
> > how hard can it be?
> >
>
> Based on what I know about harmonic drives, extremely hard.

Yes, I was being a little sarcastic. But if I don't expect to make a
_good_ one, I think I can do it.

> https://www.harmonicdrive.net/technology
>

Rather usefully that has a picture of the tooth shape.

-- 
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] I wonder if I can fix it?

[Rafael Skodlar]

On 1/5/21 9:25 AM, andy pugh wrote:

I bought an FHA-17C actuator from eBay. It was cheaper than normal,
for parts or not working.
It clearly had the cables cut off, so I decided to gamble.

It turns out that things were worse than I hoped.

https://photos.app.goo.gl/p3SL2Bwv2b9yd5XJ9

I am seriously considering trying to make a new flexspline. I mean,
how hard can it be?



Based on what I know about harmonic drives, extremely hard.
Each mechanism has a serial number on both tooth gears to be perfectly 
matched. You cannot mix and match. That explains high cost.


I happen to get my hand on few gears like that. See
https://www.harmonicdrive.net/technology

I know that people play with 3D printed plastic ones for toys etc. but 
that cannot replace metal.


--
Rafael Skodlar


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Re: [Emc-users] I wonder if I can fix it?

[Todd Zuercher]

-Original Message-
From: andy pugh  
Sent: Tuesday, January 05, 2021 12:26 PM
To: Enhanced Machine Controller (EMC) 
Subject: [Emc-users] I wonder if I can fix it?

>I bought an FHA-17C actuator from eBay. It was cheaper than normal, for parts 
>or not working.
>It clearly had the cables cut off, so I decided to gamble.
>
>It turns out that things were worse than I hoped.
>
>https://photos.app.goo.gl/p3SL2Bwv2b9yd5XJ9
>
>I am seriously considering trying to make a new flexspline. I mean, how hard 
>can it be?
>
>--
>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
>

I would imaging that there is a lot of black voodoo that goes into making one 
of those flexi spline cups.  But what do you have to loose, besides time and 
money.

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Re: [Emc-users] I wonder if I can fix it?

[David Berndt]

This is easily repaired by throwing it in the nearest round bin and buying  
a more robust Spinea cycloidal reducer and servo from ebay



On Tue, 05 Jan 2021 12:25:42 -0500, andy pugh  wrote:


I bought an FHA-17C actuator from eBay. It was cheaper than normal,
for parts or not working.
It clearly had the cables cut off, so I decided to gamble.

It turns out that things were worse than I hoped.

https://photos.app.goo.gl/p3SL2Bwv2b9yd5XJ9

I am seriously considering trying to make a new flexspline. I mean,
how hard can it be?



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Re: [Emc-users] I wonder if I can fix it?

[John Dammeyer]

Fascinating. I hope mine never fails.  Thanks for that posting.
John


> -Original Message-
> From: andy pugh [mailto:bodge...@gmail.com]
> Sent: January-05-21 10:32 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] I wonder if I can fix it?
> 
> On Tue, 5 Jan 2021 at 18:15, Mark Johnsen  wrote:
> 
> > back, pushed back again, and I think they finally gave up (not sure).
> > Why?  Because their flexspline kept breaking because of fatigue.  At least,
> > that's what I had heard.
> 
> I found this interesting article:
> https://www.nature.com/articles/srep37773
> 
> --
> 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
> 
> 
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
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Re: [Emc-users] I wonder if I can fix it?

[andy pugh]

On Tue, 5 Jan 2021 at 18:15, Mark Johnsen  wrote:

> back, pushed back again, and I think they finally gave up (not sure).
> Why?  Because their flexspline kept breaking because of fatigue.  At least,
> that's what I had heard.

I found this interesting article:
https://www.nature.com/articles/srep37773

-- 
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] I wonder if I can fix it?

[andy pugh]

On Tue, 5 Jan 2021 at 18:23, Gene Heskett  wrote:

>  That one I'd hazard a guess, has been over torqued,

I think it is fatigue, starting at the root of one tooth and growing
through the whole cup.

-- 
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] I wonder if I can fix it?

[Gene Heskett]

On Tuesday 05 January 2021 12:25:42 andy pugh wrote:

> I bought an FHA-17C actuator from eBay. It was cheaper than normal,
> for parts or not working.
> It clearly had the cables cut off, so I decided to gamble.
>
> It turns out that things were worse than I hoped.
>
> https://photos.app.goo.gl/p3SL2Bwv2b9yd5XJ9
>
> I am seriously considering trying to make a new flexspline. I mean,
> how hard can it be?

Don't waste your time trying to 3d print it, Andy.  I've tried every 
filament recipe that is made without lasting at 10 rpm output running 
overnight, they've all, even TPU looked like that in the mornings with a 
nema 17 driver.  That one I'd hazard a guess, has been over torqued, 
normal breakage for any of my attempts is at the wall/disk junction. The 
flexing is highly concentrated at the bottom of the side wall. In 15 or 
more tries, even with an oversized bearing carrier, I've not broken the 
wall like that one is. As the splines are a sliding contact, correct 
lube is very important.

Thanks Andy.

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] I wonder if I can fix it?

[Mark Johnsen]

The flexspline is the secret sauce of harmonic gearboxes.  If you can make
one (that can last), you can print money because these harmonics are used
in so many robotic applications.  The Harmonic Drive patents expired a few
years ago and there was one competitor (forget who??) who was coming out
with their version of the Harmonic drive.  The release date was pushed
back, pushed back again, and I think they finally gave up (not sure).
Why?  Because their flexspline kept breaking because of fatigue.  At least,
that's what I had heard.

I suppose if you use it for home use and it doesn't run 24/7, you could be
successful.  I'd love to see it :-)

BTW - If you know what kind of grease they use, that would be good to
know.  You should use their recommended grease.  Also, you can get away
with a lot less grease than what is required.  Although, applications may
differ.

Mark

On Tue, Jan 5, 2021 at 9:26 AM andy pugh  wrote:

>
> I am seriously considering trying to make a new flexspline. I mean,
> how hard can it be?
>
>

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Re: [Emc-users] I wonder if I can fix it?

[Todd Zuercher]

Looks a lot like the harmonic drive that failed in one of our machine's tool 
changers.  We bought the machine used and the previous owner tried to weld it 
back together.  Their repair lasted for about 6 months after we bought it.  Our 
break wasn't quite as bad though because ours only went around the base of the 
cup and wasn't split through the splines like yours.  From the looks of the 
repair on ours their weld only held in a couple of small spots, most of it 
probably was never held or broke almost instantly. 

Todd Zuercher
P. Graham Dunn Inc.
630 Henry Street 
Dalton, Ohio 44618
Phone:  (330)828-2105ext. 2031

-Original Message-
From: andy pugh  
Sent: Tuesday, January 05, 2021 12:26 PM
To: Enhanced Machine Controller (EMC) 
Subject: [Emc-users] I wonder if I can fix it?

[EXTERNAL EMAIL] Be sure links are safe.

I bought an FHA-17C actuator from eBay. It was cheaper than normal, for parts 
or not working.
It clearly had the cables cut off, so I decided to gamble.

It turns out that things were worse than I hoped.

https://photos.app.goo.gl/p3SL2Bwv2b9yd5XJ9

I am seriously considering trying to make a new flexspline. I mean, how hard 
can it be?

--
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] I wonder if I can fix it?

[John Dammeyer]

Ouch!

> -Original Message-
> From: andy pugh [mailto:bodge...@gmail.com]
> Sent: January-05-21 9:26 AM
> To: Enhanced Machine Controller (EMC)
> Subject: [Emc-users] I wonder if I can fix it?
> 
> I bought an FHA-17C actuator from eBay. It was cheaper than normal,
> for parts or not working.
> It clearly had the cables cut off, so I decided to gamble.
> 
> It turns out that things were worse than I hoped.
> 
> https://photos.app.goo.gl/p3SL2Bwv2b9yd5XJ9
> 
> I am seriously considering trying to make a new flexspline. I mean,
> how hard can it be?
> 
> --
> 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
> 
> 
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users



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[Emc-users] I wonder if I can fix it?

[andy pugh]

I bought an FHA-17C actuator from eBay. It was cheaper than normal,
for parts or not working.
It clearly had the cables cut off, so I decided to gamble.

It turns out that things were worse than I hoped.

https://photos.app.goo.gl/p3SL2Bwv2b9yd5XJ9

I am seriously considering trying to make a new flexspline. I mean,
how hard can it be?

-- 
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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