Re: [Emc-users] Cheaper than normal FHA-25B

[andrew beck]

Hey Chris.

That's awesome.  I was just looking at that video lol.

Do you know how he is designing these.  I know that the lobes are
calculated by a  equation.

It would be good to see the equations that go into this and any plug-ins he
uses etc.

I'm quite keen to build one of these.  Like you for robotics or just
anything.   And of course my 4th axis on the VMC

Regards

Andrew

On Sun, May 17, 2020, 4:39 PM Chris Albertson 
wrote:

> Paul Gould is doing good work with these reduction drives.   This video
> shows how a triple reduction system works and just how simple it is.
>
> Note that all the points of contact with the plastic lobes are ball bearing
> units.This unit is about as complex as they get and it is still easy to
> see how it works.   But do notice there must be three dozen bearings total.
> At the end of the video where he spins the drive with the drill you can see
> the bearings all around the outside of the gear rotate.This is not
> required.  Those can be made with pins or you can use a machined ring
> gear.
>
> https://youtu.be/ewoUsVMFWfU
>
> My use case for these is robotics but there is such a large overlap between
> robots and machine tools.   I am building both a power steering system for
> a robot self-drive car and a z-axis for a Harbor Freight mini mill.   I use
> the same motor and drive electronics for both of these.  The only
> difference is the mill uses a 16mm ball screw and the car uses spur gears
> But the same NEMA23 motor.   Paul is working on walking robots but there is
> no reason not to use one of his knee joints as an A-axis in a mill.  In
> both cases you put a 2000 PPR encoder on it can use closed loop control.
>
>
>
> On Sat, May 16, 2020 at 7:53 PM andrew beck 
> wrote:
> >
> > Chris
> >
> > So do they use some needle roller bearings that run on the lobes or
> > something?
> >
>
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Re: [Emc-users] Cheaper than normal FHA-25B

[Chris Albertson]

Paul Gould is doing good work with these reduction drives.   This video
shows how a triple reduction system works and just how simple it is.

Note that all the points of contact with the plastic lobes are ball bearing
units.This unit is about as complex as they get and it is still easy to
see how it works.   But do notice there must be three dozen bearings total.
At the end of the video where he spins the drive with the drill you can see
the bearings all around the outside of the gear rotate.This is not
required.  Those can be made with pins or you can use a machined ring
gear.

https://youtu.be/ewoUsVMFWfU

My use case for these is robotics but there is such a large overlap between
robots and machine tools.   I am building both a power steering system for
a robot self-drive car and a z-axis for a Harbor Freight mini mill.   I use
the same motor and drive electronics for both of these.  The only
difference is the mill uses a 16mm ball screw and the car uses spur gears
But the same NEMA23 motor.   Paul is working on walking robots but there is
no reason not to use one of his knee joints as an A-axis in a mill.  In
both cases you put a 2000 PPR encoder on it can use closed loop control.



On Sat, May 16, 2020 at 7:53 PM andrew beck 
wrote:
>
> Chris
>
> So do they use some needle roller bearings that run on the lobes or
> something?
>

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Re: [Emc-users] Cheaper than normal FHA-25B

[andrew beck]

Chris

So do they use some needle roller bearings that run on the lobes or
something?

I could make that work I reckon.  I already have the massive big angular
contact bearings and if I can make the lobe part OK then I'm away.

Add a big clamp to hold everything rigid and tight for milling and I have a
decent commercial quality 4th axis.   Might use a 1kw Chinese servo drive
on it.

Then add my harmonic drive I have for a 5th axis and I'm into 5axis
territory.

Just need to learn how to do that on linuxcnc haha.

My bearings have a 100mm ID and I'm thinking that would be good for a
hollow spindle maybe..  Not that I would need one that much.

Regards

Andrew

On Sun, May 17, 2020, 1:51 PM Chris Albertson 
wrote:

> Actually the 3D printed plastic cycloidal lobes are lasting quite a
> while.  The reason it can work is that rather then the round pins
> shown on the demo video, real systems use tiny sealed ball bearing
> units.  So there is no sliding contact on the lobes.
>
> On Sat, May 16, 2020 at 4:40 PM andrew beck 
> wrote:
> >
> > The concern I have is that the cycloidal lobes will be unHardened and
> will
> > wear out faster.
>
> --
>
> Chris Albertson
> Redondo Beach, California
>
>
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Re: [Emc-users] Cheaper than normal FHA-25B

[Chris Albertson]

Actually the 3D printed plastic cycloidal lobes are lasting quite a
while.  The reason it can work is that rather then the round pins
shown on the demo video, real systems use tiny sealed ball bearing
units.  So there is no sliding contact on the lobes.

On Sat, May 16, 2020 at 4:40 PM andrew beck  wrote:
>
> The concern I have is that the cycloidal lobes will be unHardened and will
> wear out faster.

-- 

Chris Albertson
Redondo Beach, California


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Re: [Emc-users] Cheaper than normal FHA-25B

[Ken Strauss]

I assume that you are thinking of
https://hackaday.io/project/19405-strain-wave-gear-with-timing-belts Thanks
for the interesting idea!

> -Original Message-
> From: Chris Albertson [mailto:albertson.ch...@gmail.com]
> Sent: Saturday, May 16, 2020 6:21 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] Cheaper than normal FHA-25B
>
> THere are two different kinds of drives.  The "harmonic" and
> "cycloidal".  THey both use an eccentric center gear but the teeth
> have different shape.  The cyclodal type use arcs and have fewer
> teeth.   This is why I said they could be made using average equipment
> -- just an end-mill.
>
> You can get 100:1 with a 10 tooth cyclodal by stacking.   THere are
> some smart designs where a stack of two is less then 2x tall.
>
> One more thing:   Some smart person figured out how to make a 100:
> harmonic system with no need to make an internal ring gear.  Internal
> 101 tooth gears are hard to make.   So it used a timing belt press fit
> into a hollow cylinder.  THen you can use a timming pulley as the
> eccentric.
>
> > Several of those on ebay for solid gold prices have far less outer pins
> > than teeth on the moving wheels, looks like at least 100/1 can be
> > obtained from a single stage that way but the tooth shapes seem like
> > they are not exactly fixed arcs but just fractions of full arcs.  That
> > would be more complex to make, but probably still quicker than 2 stages
> > with full arcs as the wiki page shows.
> >
> --
>
> Chris Albertson
> Redondo Beach, California
>
>
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Re: [Emc-users] Cheaper than normal FHA-25B

[andrew beck]

The concern I have is that the cycloidal lobes will be unHardened and will
wear out faster.

They really need to be Hardened.

And If I made one it would have a decent size air or hydraulic clamp to
hold everything rigid for 4th axis positional work.

On Sun, May 17, 2020, 10:23 AM Chris Albertson 
wrote:

> THere are two different kinds of drives.  The "harmonic" and
> "cycloidal".  THey both use an eccentric center gear but the teeth
> have different shape.  The cyclodal type use arcs and have fewer
> teeth.   This is why I said they could be made using average equipment
> -- just an end-mill.
>
> You can get 100:1 with a 10 tooth cyclodal by stacking.   THere are
> some smart designs where a stack of two is less then 2x tall.
>
> One more thing:   Some smart person figured out how to make a 100:
> harmonic system with no need to make an internal ring gear.  Internal
> 101 tooth gears are hard to make.   So it used a timing belt press fit
> into a hollow cylinder.  THen you can use a timming pulley as the
> eccentric.
>
> > Several of those on ebay for solid gold prices have far less outer pins
> > than teeth on the moving wheels, looks like at least 100/1 can be
> > obtained from a single stage that way but the tooth shapes seem like
> > they are not exactly fixed arcs but just fractions of full arcs.  That
> > would be more complex to make, but probably still quicker than 2 stages
> > with full arcs as the wiki page shows.
> >
> --
>
> Chris Albertson
> Redondo Beach, California
>
>
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Re: [Emc-users] Trouble with 8i20 settings.

[Curtis Dutton]

I got time to get back to my machine and indeed it seems to be working much
better now.

I tried

current-maxlim = 100
current-minlim = -100
current-scalemax = 100

and things are much snappier.


On Sat, May 16, 2020 at 4:47 PM Curtis Dutton  wrote:

> Yes the current is set to 1 or -1 while this is occurring.
>
> I'm willing to say that it may just be as fast as it will go. Which will
> be fine for my application. I just wasn't sure.
>
> But just so I understand. If I wanted my output range to be 100 to -100
>
> I would set NVMAXCURRENT 3000 (30 AMPS)
> current-maxlim = 100
> current-minlim = -100
> current-scalemax = 100
>
>
> Thanks,
>Curt
>
> On Sat, May 16, 2020 at 4:10 PM andy pugh  wrote:
>
>> On Sat, 16 May 2020 at 17:56, Curtis Dutton  wrote:
>>
>> > I've tried to look for some documentation explaining exactly how those
>> > values work, but I can't seem to find it.
>>
>> It might not be in the most obvious place.
>> http://linuxcnc.org/docs/2.7/html/man/man9/sserial.9.html#8i20
>>
>> But that comes closer to explaining max, min and scalemax in the 7i76
>> section rather than the 8i20 section.
>>
>> --
>> 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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>> https://lists.sourceforge.net/lists/listinfo/emc-users
>>
>

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Re: [Emc-users] Cheaper than normal FHA-25B

[Chris Albertson]

THere are two different kinds of drives.  The "harmonic" and
"cycloidal".  THey both use an eccentric center gear but the teeth
have different shape.  The cyclodal type use arcs and have fewer
teeth.   This is why I said they could be made using average equipment
-- just an end-mill.

You can get 100:1 with a 10 tooth cyclodal by stacking.   THere are
some smart designs where a stack of two is less then 2x tall.

One more thing:   Some smart person figured out how to make a 100:
harmonic system with no need to make an internal ring gear.  Internal
101 tooth gears are hard to make.   So it used a timing belt press fit
into a hollow cylinder.  THen you can use a timming pulley as the
eccentric.

> Several of those on ebay for solid gold prices have far less outer pins
> than teeth on the moving wheels, looks like at least 100/1 can be
> obtained from a single stage that way but the tooth shapes seem like
> they are not exactly fixed arcs but just fractions of full arcs.  That
> would be more complex to make, but probably still quicker than 2 stages
> with full arcs as the wiki page shows.
>
-- 

Chris Albertson
Redondo Beach, California


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Re: [Emc-users] Cheaper than normal FHA-25B

[Gene Heskett]

On Saturday 16 May 2020 17:13:23 Chris Albertson wrote:

> On Sat, May 16, 2020 at 12:24 PM Gene Heskett  
wrote:
> > Which then brings up the need for some math.  So how would one go
> > about getting from a 3 phase stepper motors holding power, say 3 NM
> > to lbs/ft at the output of a 12/1 cycloidal gear?
> >
> > Assuming zero losses in the bearings, which I'd guess at 5% if
> > decent bearings.
> >
> > Could that 3NM motor hold it, or even move it under cutting loads?
>
> Torque multiplies by the gear ratio.  So if the motor holds 3.0 Nm and
> there is a 10X r
> eduction then the part can be held to 30 Nm.   If you need the result
> in foot-pounds it is an easy conversion.
>
> But many times they use two reduers in series to get an effective 100x
> reduction then you have 300 Nm.  What is needed?  You need to know
> the force from your cutter and the distance from the cutter to the
> axis.  You can always adjust the cutter force by taking smaller cuts.
>
Several of those on ebay for solid gold prices have far less outer pins 
than teeth on the moving wheels, looks like at least 100/1 can be 
obtained from a single stage that way but the tooth shapes seem like 
they are not exactly fixed arcs but just fractions of full arcs.  That 
would be more complex to make, but probably still quicker than 2 stages 
with full arcs as the wiki page shows.

> > 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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> 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] Cheaper than normal FHA-25B

[Chris Albertson]

On Sat, May 16, 2020 at 12:24 PM Gene Heskett  wrote:
>
> Which then brings up the need for some math.  So how would one go about
> getting from a 3 phase stepper motors holding power, say 3 NM to lbs/ft
> at the output of a 12/1 cycloidal gear?
>
> Assuming zero losses in the bearings, which I'd guess at 5% if decent
> bearings.
>
> Could that 3NM motor hold it, or even move it under cutting loads?

Torque multiplies by the gear ratio.  So if the motor holds 3.0 Nm and
there is a 10X r
eduction then the part can be held to 30 Nm.   If you need the result
in foot-pounds it is an easy conversion.

But many times they use two reduers in series to get an effective 100x
reduction then you have 300 Nm.  What is needed?  You need to know
the force from your cutter and the distance from the cutter to the
axis.  You can always adjust the cutter force by taking smaller cuts.

> >
> >
> 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] Trouble with 8i20 settings.

[Curtis Dutton]

Yes the current is set to 1 or -1 while this is occurring.

I'm willing to say that it may just be as fast as it will go. Which will be
fine for my application. I just wasn't sure.

But just so I understand. If I wanted my output range to be 100 to -100

I would set NVMAXCURRENT 3000 (30 AMPS)
current-maxlim = 100
current-minlim = -100
current-scalemax = 100


Thanks,
   Curt

On Sat, May 16, 2020 at 4:10 PM andy pugh  wrote:

> On Sat, 16 May 2020 at 17:56, Curtis Dutton  wrote:
>
> > I've tried to look for some documentation explaining exactly how those
> > values work, but I can't seem to find it.
>
> It might not be in the most obvious place.
> http://linuxcnc.org/docs/2.7/html/man/man9/sserial.9.html#8i20
>
> But that comes closer to explaining max, min and scalemax in the 7i76
> section rather than the 8i20 section.
>
> --
> 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] Cheaper than normal FHA-25B

[Ken Strauss]

> -Original Message-
> From: Gene Heskett [mailto:ghesk...@shentel.net]
> Sent: Saturday, May 16, 2020 4:32 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Cheaper than normal FHA-25B
>
> On Saturday 16 May 2020 16:01:08 Ken Strauss wrote:
>
> > 3 Nm is about 2.21 ft-lb so at 12:1 reduction I think it would provide
> > about 26.5 ft-lb. For comparison, the Tormach microArc4 (harmonic
> > drive with NEMA 34 stepper) claims to provide a maximum holding torque
> > of 28 ft-lbs but they suggest using only half of that to avoid
> > excessive wear. I don't know the reduction ratio for their unit.
> > See https://tormach.com/microarc-4-4th-axis-38412.html
> >
> I don't know as I ever seen a nema 34 that short, and neither of those
> lb/ft rating are very impressive. I'd be a heck of a lot more
> comfortable with 100 lb/ft. With the BS-1 being a 40/1 worm, I'd expect
> well north of that when stationary.  Asking the worm to move it at 50lbs
> might tax things though.  I wonder if the cycloidal drive could be
> shrunk to serve as the worm drive on a BS-1?  Say 3" OD?


I haven't been closely following this discussion so I apologize if my
questions have already been answered.

How much does a decent sized harmonic reducer cost new (non-eBay)? Who makes
a good unit?




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Re: [Emc-users] Cheaper than normal FHA-25B

[Gene Heskett]

On Saturday 16 May 2020 16:01:08 Ken Strauss wrote:

> 3 Nm is about 2.21 ft-lb so at 12:1 reduction I think it would provide
> about 26.5 ft-lb. For comparison, the Tormach microArc4 (harmonic
> drive with NEMA 34 stepper) claims to provide a maximum holding torque
> of 28 ft-lbs but they suggest using only half of that to avoid
> excessive wear. I don't know the reduction ratio for their unit.
> See https://tormach.com/microarc-4-4th-axis-38412.html
>
I don't know as I ever seen a nema 34 that short, and neither of those 
lb/ft rating are very impressive. I'd be a heck of a lot more 
comfortable with 100 lb/ft. With the BS-1 being a 40/1 worm, I'd expect 
well north of that when stationary.  Asking the worm to move it at 50lbs 
might tax things though.  I wonder if the cycloidal drive could be 
shrunk to serve as the worm drive on a BS-1?  Say 3" OD? 


Interesting train of thought.  And small enough I might be able to make 
it on the G0704.  I'll go back and look at the wiki drawings.

> > -Original Message-
> > From: Gene Heskett [mailto:ghesk...@shentel.net]
> > Sent: Saturday, May 16, 2020 3:22 PM
> > To: emc-users@lists.sourceforge.net
> > Subject: Re: [Emc-users] Cheaper than normal FHA-25B
> >
> > On Saturday 16 May 2020 15:09:08 Chris Albertson wrote:
> > > One interesting and fun option is to make your own cycloidical
> > > reduction. These are completely buildable on a CNC mill that can
> > > do 2 1/2 D machining on mild steel.  Unlike most other gears,
> > > these can be cut from plate stock with just an end mill.   THey
> > > can be 3D printed too.
> > >
> > > See the wiki link below.  In a real system, the purple and grey
> > > parts are made from sealed bearing units and you'd have two moving
> > > plates stacked 180 degrees out of phase so as to counterbalance
> > > each other. But the good points are (1) high torque, (2) very low
> > > backlash, (3) compact size, (4) very simple 2D geometry
> > > https://en.wikipedia.org/wiki/Cycloidal_drive
> > > There are 100 Youtube videos about people making these with 3D
> > > printers but they work better with metal.   These have become
> > > popular with people building robot arms and robot legs but could
> > > also be driven with a servo motor and used as a rotational axis
> > > for a machine tool.
> > >
> > > In a machine tool application, you would place a rotational sensor
> > > on the axis and close the servo loop inside the controller.   A
> > > cycloidal system can be back-driven (just like spur gears or
> > > timing belts)  so they MUST be used in a closed-loop
> >
> > Which then brings up the need for some math.  So how would one go
> > about getting from a 3 phase stepper motors holding power, say 3 NM
> > to lbs/ft at the output of a 12/1 cycloidal gear?
> >
> > Assuming zero losses in the bearings, which I'd guess at 5% if
> > decent bearings.
> >
> > Could that 3NM motor hold it, or even move it under cutting loads?
> >
> >
> > 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] Trouble with 8i20 settings.

[andy pugh]

On Sat, 16 May 2020 at 17:56, Curtis Dutton  wrote:

> I've tried to look for some documentation explaining exactly how those
> values work, but I can't seem to find it.

It might not be in the most obvious place.
http://linuxcnc.org/docs/2.7/html/man/man9/sserial.9.html#8i20

But that comes closer to explaining max, min and scalemax in the 7i76
section rather than the 8i20 section.

-- 
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] Cheaper than normal FHA-25B

[Ken Strauss]

3 Nm is about 2.21 ft-lb so at 12:1 reduction I think it would provide about
26.5 ft-lb. For comparison, the Tormach microArc4 (harmonic drive with NEMA
34 stepper) claims to provide a maximum holding torque of 28 ft-lbs but they
suggest using only half of that to avoid excessive wear. I don't know the
reduction ratio for their unit.
See https://tormach.com/microarc-4-4th-axis-38412.html

> -Original Message-
> From: Gene Heskett [mailto:ghesk...@shentel.net]
> Sent: Saturday, May 16, 2020 3:22 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Cheaper than normal FHA-25B
>
> On Saturday 16 May 2020 15:09:08 Chris Albertson wrote:
>
> > One interesting and fun option is to make your own cycloidical
> > reduction. These are completely buildable on a CNC mill that can do 2
> > 1/2 D machining on mild steel.  Unlike most other gears, these can be
> > cut from plate stock with just an end mill.   THey can be 3D printed
> > too.
> >
> > See the wiki link below.  In a real system, the purple and grey parts
> > are made from sealed bearing units and you'd have two moving plates
> > stacked 180 degrees out of phase so as to counterbalance each other.
> > But the good points are (1) high torque, (2) very low backlash, (3)
> > compact size, (4) very simple 2D geometry
> > https://en.wikipedia.org/wiki/Cycloidal_drive
> > There are 100 Youtube videos about people making these with 3D
> > printers but they work better with metal.   These have become popular
> > with people building robot arms and robot legs but could also be
> > driven with a servo motor and used as a rotational axis for a machine
> > tool.
> >
> > In a machine tool application, you would place a rotational sensor on
> > the axis and close the servo loop inside the controller.   A cycloidal
> > system can be back-driven (just like spur gears or timing belts)  so
> > they MUST be used in a closed-loop
>
> Which then brings up the need for some math.  So how would one go about
> getting from a 3 phase stepper motors holding power, say 3 NM to lbs/ft
> at the output of a 12/1 cycloidal gear?
>
> Assuming zero losses in the bearings, which I'd guess at 5% if decent
> bearings.
>
> Could that 3NM motor hold it, or even move it under cutting loads?
> >
> >
> 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] Cheaper than normal FHA-25B

[Gene Heskett]

On Saturday 16 May 2020 15:09:08 Chris Albertson wrote:

> One interesting and fun option is to make your own cycloidical
> reduction. These are completely buildable on a CNC mill that can do 2
> 1/2 D machining on mild steel.  Unlike most other gears, these can be
> cut from plate stock with just an end mill.   THey can be 3D printed
> too.
>
> See the wiki link below.  In a real system, the purple and grey parts
> are made from sealed bearing units and you'd have two moving plates
> stacked 180 degrees out of phase so as to counterbalance each other.  
> But the good points are (1) high torque, (2) very low backlash, (3)
> compact size, (4) very simple 2D geometry
> https://en.wikipedia.org/wiki/Cycloidal_drive
> There are 100 Youtube videos about people making these with 3D
> printers but they work better with metal.   These have become popular
> with people building robot arms and robot legs but could also be
> driven with a servo motor and used as a rotational axis for a machine
> tool.
>
> In a machine tool application, you would place a rotational sensor on
> the axis and close the servo loop inside the controller.   A cycloidal
> system can be back-driven (just like spur gears or timing belts)  so
> they MUST be used in a closed-loop

Which then brings up the need for some math.  So how would one go about 
getting from a 3 phase stepper motors holding power, say 3 NM to lbs/ft 
at the output of a 12/1 cycloidal gear?

Assuming zero losses in the bearings, which I'd guess at 5% if decent 
bearings.

Could that 3NM motor hold it, or even move it under cutting loads?
>
>
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] Cheaper than normal FHA-25B

[Chris Albertson]

One interesting and fun option is to make your own cycloidical reduction.
These are completely buildable on a CNC mill that can do 2 1/2 D machining
on mild steel.  Unlike most other gears, these can be cut from plate stock
with just an end mill.   THey can be 3D printed too.

See the wiki link below.  In a real system, the purple and grey parts are
made from sealed bearing units and you'd have two moving plates stacked 180
degrees out of phase so as to counterbalance each other.   But the good
points are (1) high torque, (2) very low backlash, (3) compact size, (4)
very simple 2D geometry
https://en.wikipedia.org/wiki/Cycloidal_drive
There are 100 Youtube videos about people making these with 3D printers but
they work better with metal.   These have become popular with people
building robot arms and robot legs but could also be driven with a servo
motor and used as a rotational axis for a machine tool.

In a machine tool application, you would place a rotational sensor on the
axis and close the servo loop inside the controller.   A cycloidal system
can be back-driven (just like spur gears or timing belts)  so they MUST be
used in a closed-loop





On Sat, May 16, 2020 at 10:45 AM John Dammeyer 
wrote:

> I agree with Lester.  Searching for that description on the www.ebay.ca
> eventually does bring up that particular supplier along with about 10
> others.  All located in either China or Korea.  Most of the motors are more
> in the $800 range.   It almost looks like various companies are all
> sourcing the same images.
>
> Mine came through EBAY from the USA.  And IIRC, was about $400 US.  Not
> only that the supplier provided drawings of how they had it connected to
> their conveyor system.  And the manufacturer supplied a few scanned
> documents of the now discontinued B series.
>
> I've been bitten once by what I thought was a supplier in Italy that
> suddenly had a UK company doing the shipping that ultimately shipped
> something totally different from China.  It took six months with carefully
> documented emails with the Chinese company to get Mastercard to finally
> issue a refund.  The moment the refund came through the email address with
> the Chinese con artist company vanished as not available.
>
> It started with our shipping company sent the wrong part.
> Poor us, we had to pay shipping so perhaps we can refund 40% and you keep
> the goods?
> Poor us, perhaps 50%?
> If you ship it back then when we receive it we can refund 80%.
> When I asked for a name and phone number because Canada Post needs that
> for tracking the replies became more interesting.
> The address for return was incomplete and google maps showed it in the
> middle of some sort of residence building in China.
>
> At that point the email records were complete enough that Mastercard was
> able to reverse the charges but with a warning that it could be contested
> for another 3 or 4 months.  That expired a couple of months ago with
> nothing else from the supplier.
>
> The point is.  If you get taken be vigilant.  Keep records.  Don't be
> nasty.  And don't give up.  They rely on you either being rude or just
> taking your losses.
>
> John
>
>
>
> > -Original Message-
> > From: Lester Caine [mailto:les...@lsces.uk]
> > Sent: May-16-20 1:23 AM
> > To: emc-users@lists.sourceforge.net
> > Subject: Re: [Emc-users] Cheaper than normal FHA-25B
> >
> > On 15/05/2020 13:08, andy pugh wrote:
> > > I have no connection with the vendor, if you order one and receive
> > > dolls-house furniture instead don't blame me.
> >
> > As with many of these sellers it is questionable at times just what they
> > do actually have and where the product IS actually located. This one
> > does say shipping from China so why then is there a 'UK LocaL Warehouse'
> > in big text, and is the "Our opening times are 08:00 - 17:00 Monday -
> > Friday." UK time or Chinese time? They also obviously have no idea what
> > they are selling, so no indication where it has been salvaged from or
> > how old it's likely to be?
> >
> > When you see a nice 'UK Stock' flash actually on the images but the
> > sellers details are in Chinese, it's a good indication of someone
> > pulling the wool, but they are slipping up these days as they forget to
> > fiddle the 'located' entry and THAT says China ...
> >
> > I'm trying to pick up a couple of bits currently to finish off a radio
> > control car and hitting this problem. The parts ordered from a 'UK
> > Stockist with Royal Mail Delivery' in early April are still waiting for
> > tracking to update from a Chinese tracking number to the 'Royal Mail'
> > one but at least ebay took one look at the tracking number and refunded
> > me straight away saying 'the tracking number is invalid'. Problem now is
> > finding someone who has the parts in the UK ...
> >
> > --
> > Lester Caine - G8HFL
> > -
> > Contact - https://lsces.uk/wiki/Contact
> > L.S.Caine Electronic Services - https://lsces.uk
> > 

Re: [Emc-users] Trouble with 8i20 settings.

[Gene Heskett]

On Saturday 16 May 2020 12:53:29 Curtis Dutton wrote:

> I believe that I'm having trouble understanding how to set an 8i20 up
> properly.
>
> It is connected to a 2.5KW 200V AC servo which can take a maximum
> current of 44.5 amps. Maximum speed of 5000RPM.
>
> It is running a lathe spindle. I am able to get it to spin up but it
> seems a bit sluggish. I also would expect, when setting the current
> value to maximum output that I would see current-lim go true but it
> doesn't.
>
> NVMAXCURRENT = 3000
> current-maxlim = 30
> current-minlim = -30
> current-scalemax = 1
>
>
> 8i20 voltage says 350 ~ 351
> voltage drops to 340 while accelerating. I have 10 GA wires from the
> power supply to the 8i20 which are about 8" long. The power supply is
> an ELMO Tam-20/230 with a peak of 40A power output.
>
>
> I've tried to look for some documentation explaining exactly how those
> values work, but I can't seem to find it.
>
> Thanks,
>   Curt

Generally, for snappy response, you will need at least 2x the rated 
current available to supply the surge needed for quick response.  And 
lots more capacitance to supply the surge needed to accelerate it 
smartly w/o haveing a huge sag on voltage.  Mt guess, since the drop is 
not obviously large is that the controller is limiting the current to 
protect itself.

My G0704's stock spindle motor is rated at 90 volts and 9.7 amps to 
develop its rated 1 horsepower. But the psu I built for it, basicly out 
of my scrap box parts, has a 126 volt output and enough microfarads 
worth of filter capacitors that from a cold start, can and has tripped a 
30 amp breaker from the 126 volt line, so it gets 3 seconds worth of a 
soft start limited by a 50 ohm 200 watt resistor to get the caps 
somewhere near to a working voltage before the the 2nd SSR closes, 
bypassing the resistor. Originally supplied with a puny scr based 
controller by grizzly, could run it 2250 revs on a really good day, its 
remains are in that same junk box now, and one of Jon's Pico Systems 
pwn-servo amplifiers, which is a full 4 quadrant controller, now runs 
that spindle at 3000 revs, but being a full controller, it can pull that 
energy back out of the motor, running all that capacitance up to around 
165 volts peak, and the stop which is detected by a one shot on an 
encoder leg, then allows the change in direction to get thru to the 
controller, which also releases the speed stop and spins it back up 
using that stored energy in the capacitance to spin it back up in the 
opposite direction. All in about 400 milliseconds and not tripping the 
20 amp breaker in that slot of my service now.

Your 40 amp supply is too little, too slow. But the controller is 
probably most of the sluggish.  With lots more microfarads, it might get 
the job done better. 80 amps would be even better but probably would be 
more than the controller can tolerate even for the short term needed to 
get that snappy response.  That supply I built, has around 140,000 
microfarads of storage capacitance, on purpose to supply the surge 
needed to manhandle a big motor. Jon's pwm-servo is set to current limit 
that 9.7 amp motor at about 17 amps, and I hear the iron in the motor 
squeak from that limit being hit for maybe 50 milliseconds while its 
doing that turn around.  Sure, if it continued for any length of time it 
would be hard on the motors brushes, but in normal service its 
maybe .0001% of the time, and no brush maintenance has been needed in 
about 4 years  now.

That turnaround is profiled by a limit3 in front of the PID, so both the 
decel and accel times are controlled just enough the Z can keep up if 
doing a rigid tap with a tap big enough to need a peck cycle.

You might even consider putting the circuit breaker downstream of the 
supply, between it and the capacitance so the surge currents won't cause 
some "nuisance" trips. That will however, still subject the controller 
to the surges, which it must be able to handle with aplomb.

Bear in mind that at that power level, an accidental short with a 
screwdriver will remove a good sized piece of the screwdriver and your 
eyes will suffer spots for quite some time.  Use common sense around 
such stuff.  If you aren't comfortable doing it, don't! Get someone 
who IS qualified and pay his fee with a smile.

I wouldn't even think of advising on this if I weren't a C.E.T. and a 
retired broadcast tv engineer, used to dealing with transmitters drawing 
250 kilowatts at normal song.  Respect it folks, its made several passes 
at frying my ass but I am a survivor. Don't ask why, he hasn't told me 
yet.

I once came across a hot, smelly kearney bolt, holding 4 strands of 750 
MCM cable together, carved the insulation off the cables beside the hot 
one with my pocket knife, went to town and got another bolt, and several 
rolls of scotch 88 to tape up a new 24" crescent wrench handle I also 
bought, and installed that 5 lb kearney bolt beside the hot one, all 
while that cash cow was 

Re: [Emc-users] Trouble with 8i20 settings.

[Peter C. Wallace]

On Sat, 16 May 2020, Curtis Dutton wrote:


Date: Sat, 16 May 2020 12:53:29 -0400
From: Curtis Dutton 
Reply-To: "Enhanced Machine Controller (EMC)"

To: "Enhanced Machine Controller (EMC)" 
Subject: [Emc-users] Trouble with 8i20 settings.

I believe that I'm having trouble understanding how to set an 8i20 up
properly.

It is connected to a 2.5KW 200V AC servo which can take a maximum current
of 44.5 amps. Maximum speed of 5000RPM.

It is running a lathe spindle. I am able to get it to spin up but it seems
a bit sluggish. I also would expect, when setting the current value to
maximum output that I would see current-lim go true but it doesn't.

NVMAXCURRENT = 3000
current-maxlim = 30
current-minlim = -30
current-scalemax = 1



Those are not flags but rather settings that limit the maximum current
If scalemax is set to 1 that means that full current would occur at
a setting of +-1. Is the PID output +- 1 when accelerating?




8i20 voltage says 350 ~ 351
voltage drops to 340 while accelerating. I have 10 GA wires from the power
supply to the 8i20 which are about 8" long. The power supply is an ELMO
Tam-20/230 with a peak of 40A power output.


I've tried to look for some documentation explaining exactly how those
values work, but I can't seem to find it.

Thanks,
 Curt

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Peter Wallace
Mesa Electronics

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.



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Re: [Emc-users] Cheaper than normal FHA-25B

[James Isaac]

I had never found an analysis of repeatability or transmission accuracy in the 
advertising or Wikipedia for Cycloidal gear boxes.

Given the non engineering drawings at https://www.darali.com/page17.html, I was 
thinking they would allow greater holding power on a stepper motor in a fourth 
or fifth axis.


Thank you.

James Isaac.


From: David Berndt 
Sent: May 16, 2020 2:18 AM
To: Enhanced Machine Controller (EMC) ; Roland 
Jollivet 
Subject: Re: [Emc-users] Cheaper than normal FHA-25B

Why are you particularly worried about that? Cyclodial gear boxes and
harmonic drives are both basically 0 backlash, with potentially some lost
motion. Most are repeatable well under 1 arc minute, which compared to a
lot of rotary tables already out there. And that's something like a .0017"
displacement on a 12" radius. Angular transmission accuracy would seem to
be almost as big an issue that you'd have to start to think about if
you're concerned about those levels of backlash. Also overall mechanical
stiffness.

-Dave


On Sat, 16 May 2020 01:49:58 -0400, Roland Jollivet
 wrote:

> I've been thinking about 4th axes;
> While motorised reduction drives are readily available, the issue is
> obviously backlash.
>
> One way to make a zero backlash drive is to use two identical
> gearbox/drives. Place them at opposite ends of the axis, and pit them
> against each other by a few encoder counts.
> So they will track and retain the zero-backlash.
>
> Of course, the total power available is now less than one drive motor,
> but
> it is an option to use almost any pair of reduction drives that can be
> got.
> But there is also the cost of the second servo amp.
>
>
> On Fri, 15 May 2020 at 14:11, andy pugh  wrote:
>
>> The normally appear on eBay at up to 6x this price.
>> https://www.ebay.co.uk/itm/233587431605
>>
>> The B versions have conventional incremental encoders and hall
>> sensors, so are easy to integrate. Lots of torque, zero backlash and a
>> very strong and fancy big crossed-roller bearing make them an
>> almost-complete 4th or 5th axis just needing a bracket and a drive.
>>
>> I have no connection with the vendor, if you order one and receive
>> dolls-house furniture instead don't blame me.
>>
>> --
>> 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] Cheaper than normal FHA-25B

[John Dammeyer]

I agree with Lester.  Searching for that description on the www.ebay.ca 
eventually does bring up that particular supplier along with about 10 others.  
All located in either China or Korea.  Most of the motors are more in the $800 
range.   It almost looks like various companies are all sourcing the same 
images.

Mine came through EBAY from the USA.  And IIRC, was about $400 US.  Not only 
that the supplier provided drawings of how they had it connected to their 
conveyor system.  And the manufacturer supplied a few scanned documents of the 
now discontinued B series.

I've been bitten once by what I thought was a supplier in Italy that suddenly 
had a UK company doing the shipping that ultimately shipped something totally 
different from China.  It took six months with carefully documented emails with 
the Chinese company to get Mastercard to finally issue a refund.  The moment 
the refund came through the email address with the Chinese con artist company 
vanished as not available.

It started with our shipping company sent the wrong part.
Poor us, we had to pay shipping so perhaps we can refund 40% and you keep the 
goods?
Poor us, perhaps 50%?
If you ship it back then when we receive it we can refund 80%.
When I asked for a name and phone number because Canada Post needs that for 
tracking the replies became more interesting.
The address for return was incomplete and google maps showed it in the middle 
of some sort of residence building in China.

At that point the email records were complete enough that Mastercard was able 
to reverse the charges but with a warning that it could be contested for 
another 3 or 4 months.  That expired a couple of months ago with nothing else 
from the supplier.

The point is.  If you get taken be vigilant.  Keep records.  Don't be nasty.  
And don't give up.  They rely on you either being rude or just taking your 
losses.

John



> -Original Message-
> From: Lester Caine [mailto:les...@lsces.uk]
> Sent: May-16-20 1:23 AM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Cheaper than normal FHA-25B
> 
> On 15/05/2020 13:08, andy pugh wrote:
> > I have no connection with the vendor, if you order one and receive
> > dolls-house furniture instead don't blame me.
> 
> As with many of these sellers it is questionable at times just what they
> do actually have and where the product IS actually located. This one
> does say shipping from China so why then is there a 'UK LocaL Warehouse'
> in big text, and is the "Our opening times are 08:00 - 17:00 Monday -
> Friday." UK time or Chinese time? They also obviously have no idea what
> they are selling, so no indication where it has been salvaged from or
> how old it's likely to be?
> 
> When you see a nice 'UK Stock' flash actually on the images but the
> sellers details are in Chinese, it's a good indication of someone
> pulling the wool, but they are slipping up these days as they forget to
> fiddle the 'located' entry and THAT says China ...
> 
> I'm trying to pick up a couple of bits currently to finish off a radio
> control car and hitting this problem. The parts ordered from a 'UK
> Stockist with Royal Mail Delivery' in early April are still waiting for
> tracking to update from a Chinese tracking number to the 'Royal Mail'
> one but at least ebay took one look at the tracking number and refunded
> me straight away saying 'the tracking number is invalid'. Problem now is
> finding someone who has the parts in the UK ...
> 
> --
> Lester Caine - G8HFL
> -
> Contact - https://lsces.uk/wiki/Contact
> L.S.Caine Electronic Services - https://lsces.uk
> Model Engineers Digital Workshop - https://medw.uk
> Rainbow Digital Media - https://rainbowdigitalmedia.uk
> 
> 
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Re: [Emc-users] Cheaper than normal FHA-25B

[Gene Heskett]

On Saturday 16 May 2020 12:48:22 Chris Albertson wrote:

> Some types of motor drives don't have backlash.  Timing belts,
> cycloidal, and harmonic drives don't have enough backlash to worry
> about.  The linked harmonic drive is as good as the leadscrew on the
> other axis.
>
But slack, any, in a belt is the same as backlash and spring mixed, so 
don't allow it, period.

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] Trouble with 8i20 settings.

[Curtis Dutton]

I believe that I'm having trouble understanding how to set an 8i20 up
properly.

It is connected to a 2.5KW 200V AC servo which can take a maximum current
of 44.5 amps. Maximum speed of 5000RPM.

It is running a lathe spindle. I am able to get it to spin up but it seems
a bit sluggish. I also would expect, when setting the current value to
maximum output that I would see current-lim go true but it doesn't.

NVMAXCURRENT = 3000
current-maxlim = 30
current-minlim = -30
current-scalemax = 1


8i20 voltage says 350 ~ 351
voltage drops to 340 while accelerating. I have 10 GA wires from the power
supply to the 8i20 which are about 8" long. The power supply is an ELMO
Tam-20/230 with a peak of 40A power output.


I've tried to look for some documentation explaining exactly how those
values work, but I can't seem to find it.

Thanks,
  Curt

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Re: [Emc-users] Cheaper than normal FHA-25B

[Chris Albertson]

Some types of motor drives don't have backlash.  Timing belts,
cycloidal, and harmonic drives don't have enough backlash to worry
about.  The linked harmonic drive is as good as the leadscrew on the
other axis.

On Fri, May 15, 2020 at 10:53 PM Roland Jollivet
 wrote:
>
> I've been thinking about 4th axes;
> While motorised reduction drives are readily available, the issue is
> obviously backlash.
>
> One way to make a zero backlash drive is to use two identical
> gearbox/drives. Place them at opposite ends of the axis, and pit them
> against each other by a few encoder counts.
> So they will track and retain the zero-backlash.
>
> Of course, the total power available is now less than one drive motor, but
> it is an option to use almost any pair of reduction drives that can be got.
> But there is also the cost of the second servo amp.
>
>
> On Fri, 15 May 2020 at 14:11, andy pugh  wrote:
>
> > The normally appear on eBay at up to 6x this price.
> > https://www.ebay.co.uk/itm/233587431605
> >
> > The B versions have conventional incremental encoders and hall
> > sensors, so are easy to integrate. Lots of torque, zero backlash and a
> > very strong and fancy big crossed-roller bearing make them an
> > almost-complete 4th or 5th axis just needing a bracket and a drive.
> >
> > I have no connection with the vendor, if you order one and receive
> > dolls-house furniture instead don't blame me.
> >
> > --
> > 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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-- 

Chris Albertson
Redondo Beach, California


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Re: [Emc-users] Does anyone here have a BS-1 indexer?

[Gene Heskett]

On Saturday 16 May 2020 09:13:45 andy pugh wrote:

> On Sat, 16 May 2020 at 13:46, Gene Heskett  
wrote:
> > I ask 'cuz I'm going to see if I can find out today why I can't turn
> > the index axle on the side much more than 1 turn and it bind
>
> There is an end-thrust adjustment for the worm shaft on the opposite
> side of the unit.
> Also, the worm shaft housing is eccentric and can be rotated to either
> have low backlash or to be able to make a full rotation.
> (I imagine with a good one you can achieve both, with the one I had
> (BS0) it was an either/or proposition.

Much like the $100 4" table I have now, eccentric tolerance in both the 
worm and the worm gear were as you'd expect, sloppy. After I had 
motorized it, I set it so the motor could turn it, then ran it at speed 
back and forth several turns for a week thinking I could wear it in.  No 
diff. I've been using it, but with its backlash approaching a degree in 
places Its not been asked to do more than the hex head of a bolt. I 
needed to make a BIG wood drill and had to take cuts not over a couple 
thou or it would slip the motor as it was spiraling. I did get the holes 
drilled, but it was a PITA

I'd cut a slot in the front deck to make a wheel chair ramp for my 
missus, and was erecting guard rails around it.  Still there, still 
solid 3 years later though. Considering the quality of the treated wood 
18" stub posts inside that pretty plastic guard railing, I am impressed.

I get the impression I'll have to take it all apart, and wash out lots of 
machining debris. And there is not room under the GO704 spindle to tilt 
it upward, not enough post.  Maybe should have bought a BS-0.  Or a 
bigger mill...  I can also see a problem with my original 2 belt idea to 
drive it, I thought the side crank was on the end of the worm but I 
don't think it is.  My idea was to setup the first belt from the motor 
to a big 2 step pulley on the head tilt rotation axis, and another short 
belt down to the worm shaft, but there appears to be an intermediate 
gear inside to drive the worm. Or something since I've not taken that 
stuff off yet.

There does appear to be an 8mm tapped hole located at the tilt axis 
center on the right side but that seems a bit puny to put an idler 
pulley setup shaft on.  Thinking out loud.  People who know better 
should correct me. :)

I did find a manual for a similar version at grizzly.  Some diffs but not 
show stoppers at first read.  Obviously written by a lawyer, far more 
warnings than any real info.

Come the revolution, we are going to need a longer wall. :-\

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] Does anyone here have a BS-1 indexer?

[andy pugh]

On Sat, 16 May 2020 at 13:46, Gene Heskett  wrote:

> I ask 'cuz I'm going to see if I can find out today why I can't turn the
> index axle on the side much more than 1 turn and it bind

There is an end-thrust adjustment for the worm shaft on the opposite
side of the unit.
Also, the worm shaft housing is eccentric and can be rotated to either
have low backlash or to be able to make a full rotation.
(I imagine with a good one you can achieve both, with the one I had
(BS0) it was an either/or proposition.

-- 
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] QtPyVCP installation error

[Gene Heskett]

On Saturday 16 May 2020 07:51:52 Valerio Bellizzomi wrote:

> On Fri, 2020-05-15 at 13:40 -0500, Bari wrote:
> > On 5/15/20 1:02 PM, Valerio Bellizzomi wrote:
> > > I am using 2.8 amd64, I will the instructions tomorrow and post
> > > the result.
> > >
> > > Thanks.
> >
> > Support for QTPYVCP is really great on IRC freenode  #hazzy
>
> Launching pyvcp shows error: option -i not recognized
>
>
>
>
> hm2_5i25.0: initialized AnyIO board at :03:00.0
> Found file(REL): ./custom.hal
> Starting TASK program: milltask
> Starting DISPLAY program: pyvcp
> option -i not recognized
> Usage: pyvcp [-g WIDTHxHEIGHT+XOFFSET+YOFFSET][-c hal_component_name]
> myfile.xml
> If the component name is not specified, the basename of the xml file
> is used.
> -g options are in pixel units, XOFFSET/YOFFSET is referenced from top
> left of screen
> use -g WIDTHxHEIGHT for just setting size or -g +XOFFSET+YOFFSET for
> just position
> Shutting down and cleaning up LinuxCNC...
> Running HAL shutdown script
>
Letting my imagination out to play w/o a chaperon would seem to indicate 
that that useage could generate a 2nd pyvcp window to the right of the 
default one.  That would certainly alleviate my bitches about screen 
real estate wastage by the various buttons etc.  Like a button 3x taller 
than the text inside it. Huge waste of real estate IMO.

I assume hal_component_name would be how its buttons and pins would be 
addressed???

Thanks.
>
>
>
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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
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[Emc-users] Does anyone here have a BS-1 indexer?

[Gene Heskett]

Greetings all;

I ask 'cuz I'm going to see if I can find out today why I can't turn the 
index axle on the side much more than 1 turn and it binds, with the 
locking levers on the other side all loosened a turn or so.  Even that 
amount of turning is quite draggy.  And this came w/o anything like a 
usage or even a lube guide. And if that is supposed to be a backing 
plate for the chuck on the front of it, which came in a separate box, 
its not machined for the chuck. Its totally plain.

If anyone has a link to a tut on one of these BS-1's I'd sure appreciate 
it.

Thanks a bunch.

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] QtPyVCP installation error

[Valerio Bellizzomi]

On Fri, 2020-05-15 at 13:40 -0500, Bari wrote:
> On 5/15/20 1:02 PM, Valerio Bellizzomi wrote:
> 
> >
> > I am using 2.8 amd64, I will the instructions tomorrow and post the
> > result.
> >
> > Thanks.
> >
> Support for QTPYVCP is really great on IRC freenode  #hazzy


Launching pyvcp shows error: option -i not recognized




hm2_5i25.0: initialized AnyIO board at :03:00.0
Found file(REL): ./custom.hal
Starting TASK program: milltask
Starting DISPLAY program: pyvcp
option -i not recognized
Usage: pyvcp [-g WIDTHxHEIGHT+XOFFSET+YOFFSET][-c hal_component_name]
myfile.xml
If the component name is not specified, the basename of the xml file is
used.
-g options are in pixel units, XOFFSET/YOFFSET is referenced from top
left of screen
use -g WIDTHxHEIGHT for just setting size or -g +XOFFSET+YOFFSET for
just position
Shutting down and cleaning up LinuxCNC...
Running HAL shutdown script




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Re: [Emc-users] Cheaper than normal FHA-25B

[andy pugh]

On Sat, 16 May 2020 at 08:08, David Berndt  wrote:

> When reasonably sized harmonic drives with servo motors inbuilt are 250$
> on ebay, they are COTS.  So the answer is yes. Just buy one of those and
> move on to solving a more interesting problem or making whatever the
> machine is supposed to make.

Don't forget the very special bearing. That's probably a $500 part.

-- 
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] Cheaper than normal FHA-25B

[Lester Caine]

On 15/05/2020 13:08, andy pugh wrote:

I have no connection with the vendor, if you order one and receive
dolls-house furniture instead don't blame me.


As with many of these sellers it is questionable at times just what they 
do actually have and where the product IS actually located. This one 
does say shipping from China so why then is there a 'UK LocaL Warehouse' 
in big text, and is the "Our opening times are 08:00 - 17:00 Monday - 
Friday." UK time or Chinese time? They also obviously have no idea what 
they are selling, so no indication where it has been salvaged from or 
how old it's likely to be?


When you see a nice 'UK Stock' flash actually on the images but the 
sellers details are in Chinese, it's a good indication of someone 
pulling the wool, but they are slipping up these days as they forget to 
fiddle the 'located' entry and THAT says China ...


I'm trying to pick up a couple of bits currently to finish off a radio 
control car and hitting this problem. The parts ordered from a 'UK 
Stockist with Royal Mail Delivery' in early April are still waiting for 
tracking to update from a Chinese tracking number to the 'Royal Mail' 
one but at least ebay took one look at the tracking number and refunded 
me straight away saying 'the tracking number is invalid'. Problem now is 
finding someone who has the parts in the UK ...


--
Lester Caine - G8HFL
-
Contact - https://lsces.uk/wiki/Contact
L.S.Caine Electronic Services - https://lsces.uk
Model Engineers Digital Workshop - https://medw.uk
Rainbow Digital Media - https://rainbowdigitalmedia.uk


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Re: [Emc-users] Cheaper than normal FHA-25B

[N]

Harmonic drive but they are expensive.

> I've been thinking about 4th axes;
> While motorised reduction drives are readily available, the issue is
> obviously backlash.
> 
> One way to make a zero backlash drive is to use two identical
> gearbox/drives. Place them at opposite ends of the axis, and pit them
> against each other by a few encoder counts.
> So they will track and retain the zero-backlash.
> 
> Of course, the total power available is now less than one drive motor, but
> it is an option to use almost any pair of reduction drives that can be got.
> But there is also the cost of the second servo amp.
> 
> 
> On Fri, 15 May 2020 at 14:11, andy pugh  wrote:
> 
> > The normally appear on eBay at up to 6x this price.
> > https://www.ebay.co.uk/itm/233587431605
> >
> > The B versions have conventional incremental encoders and hall
> > sensors, so are easy to integrate. Lots of torque, zero backlash and a
> > very strong and fancy big crossed-roller bearing make them an
> > almost-complete 4th or 5th axis just needing a bracket and a drive.
> >
> > I have no connection with the vendor, if you order one and receive
> > dolls-house furniture instead don't blame me.
> >
> > --
> > 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] Cheaper than normal FHA-25B

[David Berndt]

When reasonably sized harmonic drives with servo motors inbuilt are 250$  
on ebay, they are COTS.  So the answer is yes. Just buy one of those and  
move on to solving a more interesting problem or making whatever the  
machine is supposed to make.


-Dave



On Sat, 16 May 2020 02:49:55 -0400, John Dammeyer   
wrote:



Hi Dave,
I think the question being raised is whether it's possible to create a  
zero backlash 4th or 5th axis with COTS hardware for less money than a  
harmonic drive or the cycloidal gearboxes.


John



-Original Message-
From: David Berndt [mailto:ber...@uberwin.com]
Sent: May-15-20 11:19 PM
To: Enhanced Machine Controller (EMC); Roland Jollivet
Subject: Re: [Emc-users] Cheaper than normal FHA-25B

Why are you particularly worried about that? Cyclodial gear boxes and
harmonic drives are both basically 0 backlash, with potentially some  
lost

motion. Most are repeatable well under 1 arc minute, which compared to a
lot of rotary tables already out there. And that's something like a  
.0017"
displacement on a 12" radius. Angular transmission accuracy would seem  
to

be almost as big an issue that you'd have to start to think about if
you're concerned about those levels of backlash. Also overall mechanical
stiffness.

-Dave


On Sat, 16 May 2020 01:49:58 -0400, Roland Jollivet
 wrote:

> I've been thinking about 4th axes;
> While motorised reduction drives are readily available, the issue is
> obviously backlash.
>
> One way to make a zero backlash drive is to use two identical
> gearbox/drives. Place them at opposite ends of the axis, and pit them
> against each other by a few encoder counts.
> So they will track and retain the zero-backlash.
>
> Of course, the total power available is now less than one drive motor,
> but
> it is an option to use almost any pair of reduction drives that can be
> got.
> But there is also the cost of the second servo amp.
>
>
> On Fri, 15 May 2020 at 14:11, andy pugh  wrote:
>
>> The normally appear on eBay at up to 6x this price.
>> https://www.ebay.co.uk/itm/233587431605
>>
>> The B versions have conventional incremental encoders and hall
>> sensors, so are easy to integrate. Lots of torque, zero backlash and  
a

>> very strong and fancy big crossed-roller bearing make them an
>> almost-complete 4th or 5th axis just needing a bracket and a drive.
>>
>> I have no connection with the vendor, if you order one and receive
>> dolls-house furniture instead don't blame me.
>>
>> --
>> 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@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/emc-users
>>
>
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Re: [Emc-users] Cheaper than normal FHA-25B

[andrew beck]

I don't think so.
But have dreams of machining a big 300mm cycloidal drive myself.  Large Dia
to increase rigidity and accuracy

After a point if you put any value on your time it just makes sense to go
buy a second hand cycloidal gearbox

On Sat, May 16, 2020, 6:54 PM John Dammeyer  wrote:

> Hi Dave,
> I think the question being raised is whether it's possible to create a
> zero backlash 4th or 5th axis with COTS hardware for less money than a
> harmonic drive or the cycloidal gearboxes.
>
> John
>
>
> > -Original Message-
> > From: David Berndt [mailto:ber...@uberwin.com]
> > Sent: May-15-20 11:19 PM
> > To: Enhanced Machine Controller (EMC); Roland Jollivet
> > Subject: Re: [Emc-users] Cheaper than normal FHA-25B
> >
> > Why are you particularly worried about that? Cyclodial gear boxes and
> > harmonic drives are both basically 0 backlash, with potentially some lost
> > motion. Most are repeatable well under 1 arc minute, which compared to a
> > lot of rotary tables already out there. And that's something like a
> .0017"
> > displacement on a 12" radius. Angular transmission accuracy would seem to
> > be almost as big an issue that you'd have to start to think about if
> > you're concerned about those levels of backlash. Also overall mechanical
> > stiffness.
> >
> > -Dave
> >
> >
> > On Sat, 16 May 2020 01:49:58 -0400, Roland Jollivet
> >  wrote:
> >
> > > I've been thinking about 4th axes;
> > > While motorised reduction drives are readily available, the issue is
> > > obviously backlash.
> > >
> > > One way to make a zero backlash drive is to use two identical
> > > gearbox/drives. Place them at opposite ends of the axis, and pit them
> > > against each other by a few encoder counts.
> > > So they will track and retain the zero-backlash.
> > >
> > > Of course, the total power available is now less than one drive motor,
> > > but
> > > it is an option to use almost any pair of reduction drives that can be
> > > got.
> > > But there is also the cost of the second servo amp.
> > >
> > >
> > > On Fri, 15 May 2020 at 14:11, andy pugh  wrote:
> > >
> > >> The normally appear on eBay at up to 6x this price.
> > >> https://www.ebay.co.uk/itm/233587431605
> > >>
> > >> The B versions have conventional incremental encoders and hall
> > >> sensors, so are easy to integrate. Lots of torque, zero backlash and a
> > >> very strong and fancy big crossed-roller bearing make them an
> > >> almost-complete 4th or 5th axis just needing a bracket and a drive.
> > >>
> > >> I have no connection with the vendor, if you order one and receive
> > >> dolls-house furniture instead don't blame me.
> > >>
> > >> --
> > >> 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
> > >>
> > >
> > > ___
> > > Emc-users mailing list
> > > Emc-users@lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
> >
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>
>
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Re: [Emc-users] Cheaper than normal FHA-25B

[John Dammeyer]

Hi Dave,
I think the question being raised is whether it's possible to create a zero 
backlash 4th or 5th axis with COTS hardware for less money than a harmonic 
drive or the cycloidal gearboxes.   

John


> -Original Message-
> From: David Berndt [mailto:ber...@uberwin.com]
> Sent: May-15-20 11:19 PM
> To: Enhanced Machine Controller (EMC); Roland Jollivet
> Subject: Re: [Emc-users] Cheaper than normal FHA-25B
> 
> Why are you particularly worried about that? Cyclodial gear boxes and
> harmonic drives are both basically 0 backlash, with potentially some lost
> motion. Most are repeatable well under 1 arc minute, which compared to a
> lot of rotary tables already out there. And that's something like a .0017"
> displacement on a 12" radius. Angular transmission accuracy would seem to
> be almost as big an issue that you'd have to start to think about if
> you're concerned about those levels of backlash. Also overall mechanical
> stiffness.
> 
> -Dave
> 
> 
> On Sat, 16 May 2020 01:49:58 -0400, Roland Jollivet
>  wrote:
> 
> > I've been thinking about 4th axes;
> > While motorised reduction drives are readily available, the issue is
> > obviously backlash.
> >
> > One way to make a zero backlash drive is to use two identical
> > gearbox/drives. Place them at opposite ends of the axis, and pit them
> > against each other by a few encoder counts.
> > So they will track and retain the zero-backlash.
> >
> > Of course, the total power available is now less than one drive motor,
> > but
> > it is an option to use almost any pair of reduction drives that can be
> > got.
> > But there is also the cost of the second servo amp.
> >
> >
> > On Fri, 15 May 2020 at 14:11, andy pugh  wrote:
> >
> >> The normally appear on eBay at up to 6x this price.
> >> https://www.ebay.co.uk/itm/233587431605
> >>
> >> The B versions have conventional incremental encoders and hall
> >> sensors, so are easy to integrate. Lots of torque, zero backlash and a
> >> very strong and fancy big crossed-roller bearing make them an
> >> almost-complete 4th or 5th axis just needing a bracket and a drive.
> >>
> >> I have no connection with the vendor, if you order one and receive
> >> dolls-house furniture instead don't blame me.
> >>
> >> --
> >> 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
> >>
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
> 
> 
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Re: [Emc-users] Cheaper than normal FHA-25B

[David Berndt]

Why are you particularly worried about that? Cyclodial gear boxes and  
harmonic drives are both basically 0 backlash, with potentially some lost  
motion. Most are repeatable well under 1 arc minute, which compared to a  
lot of rotary tables already out there. And that's something like a .0017"  
displacement on a 12" radius. Angular transmission accuracy would seem to  
be almost as big an issue that you'd have to start to think about if  
you're concerned about those levels of backlash. Also overall mechanical  
stiffness.


-Dave


On Sat, 16 May 2020 01:49:58 -0400, Roland Jollivet  
 wrote:



I've been thinking about 4th axes;
While motorised reduction drives are readily available, the issue is
obviously backlash.

One way to make a zero backlash drive is to use two identical
gearbox/drives. Place them at opposite ends of the axis, and pit them
against each other by a few encoder counts.
So they will track and retain the zero-backlash.

Of course, the total power available is now less than one drive motor,  
but
it is an option to use almost any pair of reduction drives that can be  
got.

But there is also the cost of the second servo amp.


On Fri, 15 May 2020 at 14:11, andy pugh  wrote:


The normally appear on eBay at up to 6x this price.
https://www.ebay.co.uk/itm/233587431605

The B versions have conventional incremental encoders and hall
sensors, so are easy to integrate. Lots of torque, zero backlash and a
very strong and fancy big crossed-roller bearing make them an
almost-complete 4th or 5th axis just needing a bracket and a drive.

I have no connection with the vendor, if you order one and receive
dolls-house furniture instead don't blame me.

--
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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