Re: [Emc-users] Bed isn't flat on my 6040.

[marcus . bowman]

On 2021-01-06 04:25, Bruce Layne wrote:

Why don't you just install a spoil board and machine it flat like most
people do with a CNC router?

When I converted my mill, I followed some published instructions for an 
identical mill, and added ballscrews. That involved machining a shallow 
'trench' on the underside of the bed. I know machining a casting is 
always risky, but I trusted the instructions and figured the bed must be 
sufficiently well seasoned or stress relieved, so I went ahead.
Of course the bed bowed along the Y axis, quite noticeably. I then took 
it to the only machine shop in this area and spoke to the foreman. By 
pure luck, they had a grinder with a large bed, and the foreman was 
sufficiently interested in my attempts to convert my mill that he used 
the job as an example for the apprentices. I got a beautifully flat bed, 
nicely finished, and they got a box of prizes for their annual golf 
competition.
A couple of months later, the big grinder went in the skip, along with 
all the other manual machines. The factory concentrated on CNC machining 
of toolheads for the oil drilling industry. With the downturn in recent 
times, the factory has gone, so no more machine shops in this area.


In the absence of someone to do a surface grinding job, I would do one 
of two things.
First, as Bruce suggests, I would mount a plate on the bed and flycut it 
flat. If you drill an array of holes, tap some and ream others for pins, 
you will have a handy way of securing work, holding your vice, jig, 
fixtures etc.  It may be difficult to reach the whole of the table, so a 
good alternative is to mount a couple of blocks parallel to Y and flycut 
the tops of those, then bolt a plate to the tops. Even with my flat bed, 
I use this arrangement as it locates the work a little higher. The top 
plate has bolt holes and pin holes and I use those to hold a selection 
of fixtures for various jobs. I seldom remove the sub-plate and revert 
to the bed. You may be able to buy T-slotted table tops from other mills 
(SEIG table tops are available in the UK in small and large sizes at 
reasonable prices). Mount one of those on the blocks.
A second approach, developed because of a particular job that keeps 
reappearing, is to mount a long SEIG table top on L-shaped legs using a 
tilting arrangement which pivots the table near the top front, along the 
X axis. That gives me a table large enough to hold large-ish plates so 
that I can machine one edge at an angle. It has been useful for other 
jobs too. Adjustment is from -5 to a positive angle which depends on the 
height of the legs.


Marcus


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Re: [Emc-users] Bed isn't flat on my 6040.

[Bruce Layne]

Why don't you just install a spoil board and machine it flat like most
people do with a CNC router?



On 1/5/21 10:48 PM, Gene Heskett wrote:
> Greetings all;
>
> I find on a simple jobs tonight, that the bed isn't flat, and that I need 
> to scan it for lincurve data.
>
> But this would be a true 3d need as it needs correction in both X and Y 
> travel. lincurve isn't made to do that.  So how might that be done?
>
> Thanks.
>
> Cheers, Gene Heskett


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[Emc-users] Bed isn't flat on my 6040.

[Gene Heskett]

Greetings all;

I find on a simple jobs tonight, that the bed isn't flat, and that I need 
to scan it for lincurve data.

But this would be a true 3d need as it needs correction in both X and Y 
travel. lincurve isn't made to do that.  So how might that be done?

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
Genes Web page 


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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
> 
> 
> ___
> Emc-users mailing list
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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
> 
> 
> ___
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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] stepgen step rate

[Gene Heskett]

On Tuesday 05 January 2021 10:47:16 andy pugh wrote:

> On Tue, 5 Jan 2021 at 15:40, Thomas J Powderly  
wrote:
> > Thats a max step/sec of 1 for that particular sequence of 2
> > steps.
> >
> > That sequence can happen at anytime in a cnc path.
>
> Not so. A stepper will only ever reverse at zero speed, when the step
> rate is zero. So you don't need to make allowances for setup.

This might be so, but zero speed is very fleeting for the reversal at the 
bottom of a g33.1. Even if being sequenced by hal tricks like I am. And 
a step loss  at the bottom turnaround could cause the sloppy oversized 
threads I am getting when I have to peck exec with a descending turn 
around due to lack of torque to drive the tap of that size in one stroke 
so I write a peck loop.

I'd have no trouble expanding that spindle stopped window, its a setp in 
my hal code, so how long a dead time between encoder pulses do I need in 
order to guarantee no loss of Z steps in that condition?

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?

[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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Re: [Emc-users] stepgen step rate

[andy pugh]

On Tue, 5 Jan 2021 at 16:24, Thomas J Powderly  wrote:

> but , a special case ignores/allows for when the velocity is zero.

I don't think that it is a special case, just that because the
reversals always happen at very low step rates you don't need to
factor in the setup time when calculating maximum step rate.

Also look at the "reset" function, which allows for steps shorter than
a full base period, and for a step every base period.


-- 
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] stepgen step rate

[Thomas J Powderly]

Thx Andy

I will look for what the code says it does when there's a zero speed 
reversal.


So I take it is true that the 4 values _are_ up rounded to the base 
period length.


but , a special case ignores/allows for when the velocity is zero.

I didnt see that yet.

TomP

On 1/5/21 10:47 PM, andy pugh wrote:

On Tue, 5 Jan 2021 at 15:40, Thomas J Powderly  wrote:


Thats a max step/sec of 1 for that particular sequence of 2 steps.

That sequence can happen at anytime in a cnc path.

Not so. A stepper will only ever reverse at zero speed, when the step
rate is zero. So you don't need to make allowances for setup.




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Re: [Emc-users] stepgen step rate

[andy pugh]

On Tue, 5 Jan 2021 at 15:40, Thomas J Powderly  wrote:

> Thats a max step/sec of 1 for that particular sequence of 2 steps.
>
> That sequence can happen at anytime in a cnc path.

Not so. A stepper will only ever reverse at zero speed, when the step
rate is zero. So you don't need to make allowances for setup.

-- 
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] stepgen step rate

[Thomas J Powderly]

Hello

I am studying the stepgen.c code.

I see that the 4 parameters

  steplen stepspace dirhold and dirsetup

are rounded up ( ulceil() )

to the next larger interger value of the BASE period.


That means for my Gecko 540, the 1uS Steplen 2uSstepspace 200nSdirhold 
and 200uS dirsetup


all become 25uS for the typical 25uS Base thread period.


But the DirSetup and DirHold must co-exist in a single StepSpace when 
the direction reverses between 2 step pulses.



I think that makes the stepspace become 50uS ( to accomodate the dirhold 
plus dirsetup )


and the steplen and stepspace now total 75uS.


Thats a max step/sec of 1 for that particular sequence of 2 steps.

That sequence can happen at anytime in a cnc path.

Som I must allow for these 'random' ocurrances,

and this lowers the max steprate to 1 ( 1 sec / .75 )..


The commonly mentioned 2 steps per second rate appears to be only 
for unchanging direction


and 1 steps per second for useful paths.

( 2 for drag racing  vs 1 for gymkhana )


Coreections invited, I am still studying.


Thx TomP



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[Emc-users] GUI Feature Request

[Todd Zuercher]

I've noticed what appears to be a lot of new development of new GUIs for 
Linuxcnc lately.  Here is an idea that I would love to see implemented in a new 
GUI, but I do not have the programming skills to implement it.  For our 
production machines it would be nice for the supervisors to be able to set up a 
que of g-code files for shifts to run.  The que would be a list of g-code 
files, and their location paths (possibly a network location), the number of 
repeats to run, and possibly a material to be used description.  Then the 
machine operators would simply unload/load the machine, and press start, once 
the required number of runs is completed the gui would automatically load the 
next g-code file in the que and prompt the user what material to load for the 
next run.  How hard might something like this be to implement?


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


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