Re: [Emc-users] DC Servo issues

[Gene Heskett]

On Wednesday 22 September 2021 05:18:40 John Dammeyer wrote:

> > From: Gene Heskett [mailto:ghesk...@shentel.net]
> >
> > On Wednesday 22 September 2021 00:27:53 John Dammeyer wrote:
> > > I love it when a plan comes together.
> > >
> > > John
> >
> > I'm surprised you kept the acme screw.
> >
> > Cheers, Gene Heskett
>
> This is a slow on-going project.  Ball screws are on the list.
>
> John

Ahh, resembles some of mine then. ;o) Do carry on.
>
>
>
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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] DC Servo issues

[John Dammeyer]

> From: Gene Heskett [mailto:ghesk...@shentel.net]
> On Wednesday 22 September 2021 00:27:53 John Dammeyer wrote:
> 
> > I love it when a plan comes together.  

> > John
> 
> I'm surprised you kept the acme screw. 
 
> Cheers, Gene Heskett

This is a slow on-going project.  Ball screws are on the list.

John




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Re: [Emc-users] DC Servo issues

[Gene Heskett]

On Wednesday 22 September 2021 00:27:53 John Dammeyer wrote:

> I love it when a plan comes together.  Tested out the Bergerda 1.27NM
> motor on the Y axis. I was worried that it might not carry the extra
> weight as the DC Servos were 1.6NM.
>
> Well.  Silky smooth.  For a 2.8A motor it never has more than about
> 1.0A current draw and about 0.34NM based on what the servo drive
> reports.  Sounds nice too.  And that's with two heavy vices and a
> rotary table all the way up to 3000 RPM 4:1 to 0.2" pitch ACME screw.
>
> Time to put the other one on the X axis and verify that the positions
> remain accurate.
>
> John

I'm surprised you kept the acme screw. I used a stationary acme as z on 
my hf micromill, first mill I cnc'd. with a rotating nut design useing 
two nook nuts. Had to adjust the phases of the 2 nuts to keep the 
backlash under 5 thou, several times a year. First thing I did to the 
bigger G0704 was put a ball screw kit in it. Never looked back, 5 years 
later backlash is still under 2 thou. Now my biggest problem is that the 
post isn't plumb. So its impossible to tram correctly. But my garage is 
full, no room for a bigger, more accurately cast nachine.
>
> > -Original Message-
> > From: Bari [mailto:bari00...@gmail.com]
> > Sent: September-18-21 11:30 PM
> > To: emc-users@lists.sourceforge.net
> > Subject: Re: [Emc-users] DC Servo issues
> >
> > On 9/19/21 00:44, John Dammeyer wrote:
> > > Over 10 years ago I bought two of these for the XY axis of the
> > > mill.
> > > https://www.automationtechnologiesinc.com/products-page/dc-servo-m
> > >otor/nema34-1125ozin-dual-shaft-servo-motor
> > >
> > > One of the things that showed up right away was that with
> > > identical drives one motor ran hotter than the other.  Further
> >
> > investigation showed the resistance of the windings was different
> > with the warmer motor having the lower resistance and inductance
> > which matched the spec sheet.  By then it was too late to return the
> > high resistance one so I decided to put what appeared to be the on
> > spec motor on the Y axis since it had to carry more weight.  The X
> > axis got the cooler and higher resistance motor.
> >
> > > Especially since AutomationTechnologies wouldn't replace the motor
> > > even though it was clearly out of spec.  Not about to buy
> >
> > anything else from them.
> >
> >
> > They are local for me. The owner is a nice enough guy but he also
> > problems with getting reliable consistent parts from his homeland.
> >
> > I only buy things from them that I expect to be like a kit that
> > needs to be cleaned and assembled properly before use. I have had to
> > return radial bearings with detents and linear bearings with crud
> > inside or flat spots. We call them crunchy bearings. CNC mills come
> > with red oxide treated fasteners and without nuts on the end of
> > ballscrews so you can't adjust preloads unless you shim or replace
> > with proper screws. Cables are assembled without the use of strain
> > reliefs.
> >
> > Red oxide treated fasteners� https://postimg.cc/jnhmsRhq
> >
> > No strain relief� https://postimg.cc/7bqwTvvy
> >
> > 1mm of lash� https://postimg.cc/w1bvqpWk
> >
> >
> >
> >
> > ___
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> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
> ___
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>


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Re: [Emc-users] DC Servo issues

[John Dammeyer]

I love it when a plan comes together.  Tested out the Bergerda 1.27NM motor on 
the Y axis. I was worried that it might not carry the extra weight as the DC 
Servos were 1.6NM.

Well.  Silky smooth.  For a 2.8A motor it never has more than about 1.0A 
current draw and about 0.34NM based on what the servo drive reports.  Sounds 
nice too.  And that's with two heavy vices and a rotary table all the way up to 
3000 RPM 4:1 to 0.2" pitch ACME screw.

Time to put the other one on the X axis and verify that the positions remain 
accurate.

John 

> -Original Message-
> From: Bari [mailto:bari00...@gmail.com]
> Sent: September-18-21 11:30 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] DC Servo issues
> 
> On 9/19/21 00:44, John Dammeyer wrote:
> 
> > Over 10 years ago I bought two of these for the XY axis of the mill.
> > https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor
> 
> > One of the things that showed up right away was that with identical drives 
> > one motor ran hotter than the other.  Further
> investigation showed the resistance of the windings was different with the 
> warmer motor having the lower resistance and
> inductance which matched the spec sheet.  By then it was too late to return 
> the high resistance one so I decided to put what
> appeared to be the on spec motor on the Y axis since it had to carry more 
> weight.  The X axis got the cooler and higher resistance
> motor.
> > Especially since AutomationTechnologies wouldn't replace the motor even 
> > though it was clearly out of spec.  Not about to buy
> anything else from them.
> 
> 
> They are local for me. The owner is a nice enough guy but he also
> problems with getting reliable consistent parts from his homeland.
> 
> I only buy things from them that I expect to be like a kit that needs to
> be cleaned and assembled properly before use. I have had to return
> radial bearings with detents and linear bearings with crud inside or
> flat spots. We call them crunchy bearings. CNC mills come with red oxide
> treated fasteners and without nuts on the end of ballscrews so you can't
> adjust preloads unless you shim or replace with proper screws. Cables
> are assembled without the use of strain reliefs.
> 
> Red oxide treated fasteners� https://postimg.cc/jnhmsRhq
> 
> No strain relief� https://postimg.cc/7bqwTvvy
> 
> 1mm of lash� https://postimg.cc/w1bvqpWk
> 
> 
> 
> 
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Re: [Emc-users] DC Servo issues

[John Dammeyer]

I find the pendant great for that.  The only issue has been with setting tool 
height as selecting and moving an axis with the pendant doesn't change the 
buttons on the AXIS screen.  So I sneak up to the right hight but perhaps X is 
still selected for the keyboard jog buttons.  Then I click on set tool height 
and instead it sets the X offset.  Makes things interesting.

Well motors have been swapped back.  CAM generated for new Y axis plate to hold 
the Bergerda Motor.  Might as well try and see if I can move the Y Axis system 
with that small Bergerda AC Servo.  It did fine on the X but never did try the 
Y.

John




> -Original Message-
> From: Sam Sokolik [mailto:samco...@gmail.com]
> Sent: September-19-21 1:30 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] DC Servo issues
> 
> Yes..  I agree.   Though my favorite thing to setup on a linuxcnc machine
> is an encoder wheel for jogging and overrides...   What I use the most is
> maximum velocity over ride..  allows you to sneak up on part...
> 
> On Sun, Sep 19, 2021, 2:53 PM John Dammeyer  wrote:
> 
> > Hi Sam,
> > I must admit there's a certain amount of fear every time I press the go
> > button for a CNC program.  Especially when I started mucking around with
> > tool #'s and offsets.   My hand now overs over ESTOP when I press start.
> > Watching a tool that appears too low scream over to the part held in the
> > vise at a G0 180 ipm is not for the faint of heart.
> >
> > But then the first time I apply power to a newly assembled power supply my
> > heart is also in my throat.  For one product, if the Pick and Place people
> > didn't use enough solder under the ground pad of the regulator chip (the
> > only ground connection too), it would fry and take out the 8 SMD power
> > transistors for the dual supply.  Very difficult to repair.
> >
> > On the servo side, the caps are 200V rated as are the 50A transistors so
> > theoretically I could run one with 115VAC as the 165VDC supply.   That
> > would certainly provide the force to drive more current into the motor
> > windings and create the speed desired.  With 105V the motor can reach 3000
> > RPM with a lighter load, otherwise it would never work on the X axis but
> > the torque might also just be on the edge during acceleration in one
> > direction and not the other.
> >
> > Or build up a small circuit so I can measure the instantaneous DC current
> > with the scope (don't have a current probe) and see how much current the
> > motors are really drawing.   Torque is Amps x Turns and if the voltage
> > isn't there to push the amps then following errors are likely.
> >
> > John
> >
> >
> >
> > > -Original Message-
> > > From: Sam Sokolik [mailto:samco...@gmail.com]
> > > Sent: September-19-21 12:11 PM
> > > To: Enhanced Machine Controller (EMC)
> > > Subject: Re: [Emc-users] DC Servo issues
> > >
> > > Lol..  I certainly love the electrics part more than the machining most
> > of
> > > the time...
> > >
> > > On Sun, Sep 19, 2021, 2:07 PM John Dammeyer 
> > wrote:
> > >
> > > > Hi Sam,
> > > > See below.
> > > > > From: Sam Sokolik [mailto:samco...@gmail.com]
> > > > >
> > > > > I have never used servo drives that close the loop..   I have always
> > had
> > > > > great luck with normal closed loop within linuxcnc.  (cheap used amc
> > > > > drives)
> > > > >
> > > > > (Actually - I take that back - I have used the stmbl drives. so far
> > only
> > > > > for a spindle..)
> > > > >
> > > > > This is of course using mesa analog interface hardware.
> > > > >
> > > > > The only time I had issues with encoder counting was when I thought I
> > > > could
> > > > > get by with single ended encoders going over 8 ft...
> > > > >
> > > > > Look at something like this..  2 counts per rev,  2 axis with
> > 4000?
> > > > > counts per rev...  (and the encoders came installed on the servo,
> > single
> > > > > ended and I think they are us-digital)
> > > > > If I was missing counts during these complicated sync moves - you
> > would
> > > > > certainly see it.
> > > > >
> > > > > https://www.youtube.com/watch?v=-4sKHBh6rDk
> > > > >
> > > > > (plus no 3rd party software to tune...)  - Granted you have the
> > dri

Re: [Emc-users] DC Servo issues

[Sam Sokolik]

Yes..  I agree.   Though my favorite thing to setup on a linuxcnc machine
is an encoder wheel for jogging and overrides...   What I use the most is
maximum velocity over ride..  allows you to sneak up on part...

On Sun, Sep 19, 2021, 2:53 PM John Dammeyer  wrote:

> Hi Sam,
> I must admit there's a certain amount of fear every time I press the go
> button for a CNC program.  Especially when I started mucking around with
> tool #'s and offsets.   My hand now overs over ESTOP when I press start.
> Watching a tool that appears too low scream over to the part held in the
> vise at a G0 180 ipm is not for the faint of heart.
>
> But then the first time I apply power to a newly assembled power supply my
> heart is also in my throat.  For one product, if the Pick and Place people
> didn't use enough solder under the ground pad of the regulator chip (the
> only ground connection too), it would fry and take out the 8 SMD power
> transistors for the dual supply.  Very difficult to repair.
>
> On the servo side, the caps are 200V rated as are the 50A transistors so
> theoretically I could run one with 115VAC as the 165VDC supply.   That
> would certainly provide the force to drive more current into the motor
> windings and create the speed desired.  With 105V the motor can reach 3000
> RPM with a lighter load, otherwise it would never work on the X axis but
> the torque might also just be on the edge during acceleration in one
> direction and not the other.
>
> Or build up a small circuit so I can measure the instantaneous DC current
> with the scope (don't have a current probe) and see how much current the
> motors are really drawing.   Torque is Amps x Turns and if the voltage
> isn't there to push the amps then following errors are likely.
>
> John
>
>
>
> > -Original Message-
> > From: Sam Sokolik [mailto:samco...@gmail.com]
> > Sent: September-19-21 12:11 PM
> > To: Enhanced Machine Controller (EMC)
> > Subject: Re: [Emc-users] DC Servo issues
> >
> > Lol..  I certainly love the electrics part more than the machining most
> of
> > the time...
> >
> > On Sun, Sep 19, 2021, 2:07 PM John Dammeyer 
> wrote:
> >
> > > Hi Sam,
> > > See below.
> > > > From: Sam Sokolik [mailto:samco...@gmail.com]
> > > >
> > > > I have never used servo drives that close the loop..   I have always
> had
> > > > great luck with normal closed loop within linuxcnc.  (cheap used amc
> > > > drives)
> > > >
> > > > (Actually - I take that back - I have used the stmbl drives. so far
> only
> > > > for a spindle..)
> > > >
> > > > This is of course using mesa analog interface hardware.
> > > >
> > > > The only time I had issues with encoder counting was when I thought I
> > > could
> > > > get by with single ended encoders going over 8 ft...
> > > >
> > > > Look at something like this..  2 counts per rev,  2 axis with
> 4000?
> > > > counts per rev...  (and the encoders came installed on the servo,
> single
> > > > ended and I think they are us-digital)
> > > > If I was missing counts during these complicated sync moves - you
> would
> > > > certainly see it.
> > > >
> > > > https://www.youtube.com/watch?v=-4sKHBh6rDk
> > > >
> > > > (plus no 3rd party software to tune...)  - Granted you have the
> drives
> > > and
> > > > are familiar with them - at what point do you give up?
> > > >
> > > > sam
> > >
> > > That's the question.  One possibility to try is to grab 110VAC line
> > > voltage. Put a bridge and caps on it and drive that motor with more
> than
> > > the 105VDC power supply.  I'll have to check if my transistors are
> rated
> > > for the 165VDC rectified voltage and I really would rather have them be
> > > 250V transitors.   And then there's the filters on the board too. The
> UHU
> > > circuit was originally for up to about 75V.  The HP_UHU came about for
> > > higher voltage drives;  Just don't know if I built mine for more than
> > > 125VDC although the circuit design parts are for 11A.
> > >
> > > I _have_ tried one these motors with the STMBL but could never get it
> > > tuned and support from the designers was inadequate to help me so I
> gave
> > > up.
> > >
> > > I'd rather be machining...
> > >
> > > John
> > >
> > >
> > >
> > > >

Re: [Emc-users] DC Servo issues

[John Dammeyer]

I have a shunt circuit on the 105VDC supply for that.   I could build up 
another one of those PC boards to do it for a higher voltage supply.  But is it 
all worth it for one motor that does not match the data sheet winding 
resistance and shows up with problems.

John

> -Original Message-
> From: John Figie [mailto:zephyr9...@gmail.com]
> Sent: September-19-21 12:14 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] DC Servo issues
> 
> John Figie
> 
> 
> On Sun, Sep 19, 2021 at 2:07 PM John Dammeyer 
> wrote:
> 
> >
> >
> > That's the question.  One possibility to try is to grab 110VAC line
> > voltage. Put a bridge and caps on it and drive that motor with more than
> > the 105VDC power supply.  I'll have to check if my transistors are rated
> > for the 165VDC rectified voltage and I really would rather have them be
> > 250V transitors.
> 
> 
> I think you will need the 250V transistors and also need to consider a
> shunt resistor and switch to keep the bus voltage from going too high when
> you rapidly decelerate a motor.
> 
> 
> > And then there's the filters on the board too. The UHU circuit was
> > originally for up to about 75V.  The HP_UHU came about for higher voltage
> > drives;  Just don't know if I built mine for more than 125VDC although the
> > circuit design parts are for 11A.
> >
> > I _have_ tried one these motors with the STMBL but could never get it
> > tuned and support from the designers was inadequate to help me so I gave
> > up.
> >
> > I'd rather be machining...
> >
> > John
> >
> >
> >
> 
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Re: [Emc-users] DC Servo issues

[John Dammeyer]

Hi Sam,
I must admit there's a certain amount of fear every time I press the go button 
for a CNC program.  Especially when I started mucking around with tool #'s and 
offsets.   My hand now overs over ESTOP when I press start.  Watching a tool 
that appears too low scream over to the part held in the vise at a G0 180 ipm 
is not for the faint of heart.

But then the first time I apply power to a newly assembled power supply my 
heart is also in my throat.  For one product, if the Pick and Place people 
didn't use enough solder under the ground pad of the regulator chip (the only 
ground connection too), it would fry and take out the 8 SMD power transistors 
for the dual supply.  Very difficult to repair.

On the servo side, the caps are 200V rated as are the 50A transistors so 
theoretically I could run one with 115VAC as the 165VDC supply.   That would 
certainly provide the force to drive more current into the motor windings and 
create the speed desired.  With 105V the motor can reach 3000 RPM with a 
lighter load, otherwise it would never work on the X axis but the torque might 
also just be on the edge during acceleration in one direction and not the other.

Or build up a small circuit so I can measure the instantaneous DC current with 
the scope (don't have a current probe) and see how much current the motors are 
really drawing.   Torque is Amps x Turns and if the voltage isn't there to push 
the amps then following errors are likely.

John



> -Original Message-
> From: Sam Sokolik [mailto:samco...@gmail.com]
> Sent: September-19-21 12:11 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] DC Servo issues
> 
> Lol..  I certainly love the electrics part more than the machining most of
> the time...
> 
> On Sun, Sep 19, 2021, 2:07 PM John Dammeyer  wrote:
> 
> > Hi Sam,
> > See below.
> > > From: Sam Sokolik [mailto:samco...@gmail.com]
> > >
> > > I have never used servo drives that close the loop..   I have always had
> > > great luck with normal closed loop within linuxcnc.  (cheap used amc
> > > drives)
> > >
> > > (Actually - I take that back - I have used the stmbl drives. so far only
> > > for a spindle..)
> > >
> > > This is of course using mesa analog interface hardware.
> > >
> > > The only time I had issues with encoder counting was when I thought I
> > could
> > > get by with single ended encoders going over 8 ft...
> > >
> > > Look at something like this..  2 counts per rev,  2 axis with 4000?
> > > counts per rev...  (and the encoders came installed on the servo, single
> > > ended and I think they are us-digital)
> > > If I was missing counts during these complicated sync moves - you would
> > > certainly see it.
> > >
> > > https://www.youtube.com/watch?v=-4sKHBh6rDk
> > >
> > > (plus no 3rd party software to tune...)  - Granted you have the drives
> > and
> > > are familiar with them - at what point do you give up?
> > >
> > > sam
> >
> > That's the question.  One possibility to try is to grab 110VAC line
> > voltage. Put a bridge and caps on it and drive that motor with more than
> > the 105VDC power supply.  I'll have to check if my transistors are rated
> > for the 165VDC rectified voltage and I really would rather have them be
> > 250V transitors.   And then there's the filters on the board too. The UHU
> > circuit was originally for up to about 75V.  The HP_UHU came about for
> > higher voltage drives;  Just don't know if I built mine for more than
> > 125VDC although the circuit design parts are for 11A.
> >
> > I _have_ tried one these motors with the STMBL but could never get it
> > tuned and support from the designers was inadequate to help me so I gave
> > up.
> >
> > I'd rather be machining...
> >
> > John
> >
> >
> >
> > >
> > > On Sun, Sep 19, 2021 at 12:59 PM John Dammeyer 
> > > wrote:
> > >
> > > > Hi Rick,
> > > > It may also have something to do with the DC Servo drive electronics.
> > > > Although it's differential encoder signalling the design may have
> > internal
> > > > issues that are somewhat corrected by the Henk Olsson module.  I had
> > both a
> > > > small electrolytic and ceramic capacitors right by the US Digital
> > encoders,
> > > > which BTW, have been discontinued for a few years.  Perhaps that's why?
> > > > Issues?
> > > >
> > > > I swapped the X and Y motor/encoder pair and sure enough the pro

Re: [Emc-users] DC Servo issues

[Rick Moscoloni]

Is really a pain to debug such issues, i have an old machine with the same
motors connected to gecko 340 (but I have to remove the multiplier), us
digital encoders wont work without the caps.
I hope you can resolve this issue soon, i pull my hair when things like
this show up!
Go John!

El dom, 19 sept 2021 a las 14:59, John Dammeyer ()
escribió:

> Hi Rick,
> It may also have something to do with the DC Servo drive electronics.
> Although it's differential encoder signalling the design may have internal
> issues that are somewhat corrected by the Henk Olsson module.  I had both a
> small electrolytic and ceramic capacitors right by the US Digital encoders,
> which BTW, have been discontinued for a few years.  Perhaps that's why?
> Issues?
>
> I swapped the X and Y motor/encoder pair and sure enough the problem moved
> to the Y axis along with now only 120 IPM instead of 150 IPM.  Above that I
> get following errors.  Given that this motor has a higher winding
> resistance I'm going to guess it's not a 90VDC motor but is more likely a
> 180VDC motor that was shipped as a 90VDC.   Maybe the loading introduces
> noise in one direction that fools the quadrature encoder.  It's very
> strange that the following errors are only in one direction.
>
> At $145US plus shipping, since Automation Technologies won't replace it,
> I'm going to cast a new mounting plate for one of the slightly smaller
> 1.27NM Bergerda AC servos.  They were destined for the ball screw upgrade
> (and I'd ordered the wrong size thinking they were the same torque as the
> DC ones).  So we'll see.  If the Bergerda does well on the heavier Y axis
> then problem solved.
>
> More as it unfolds.
>
> Oh I swapped motor/encoder sets between X and Y,and with the Y motor
> running the X axis the test program that runs the table back and forth no
> longer has a slightly different sound between changing direction CW
> compared to CCW.  So it appears that's also on the motor and not LinuxCNC
> nor the MESA.  And absolutely no errors in position on X.  Only now on the
> Y instead.  That lets the HP_UHU servo drive off the hook too.
>
> John
>
> > -Original Message-----
> > From: Rick Moscoloni [mailto:rmoscol...@gmail.com]
> > Sent: September-19-21 10:12 AM
> > To: Enhanced Machine Controller (EMC)
> > Subject: Re: [Emc-users] DC Servo issues
> >
> > us digital encoders with a capacitor across dc+and- works without a
> > fault
> >
> > El dom, 19 sept 2021 a las 2:49, John Dammeyer ( >)
> > escribi�:
> >
> > > Over 10 years ago I bought two of these for the XY axis of the mill.
> > >
> > >
> https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor
> > >
> > > Also from US Digital the 250 line encoders.
> > > I had assembled HP_UHU kits and had on standby the Henrik Olsson
> > > replacement PIC processor modules although this photo shows the
> original
> > > processor.
> > > http://www.autoartisans.com/mill/HP_UHU_Modified.jpg
> > >
> > > One of the things that showed up right away was that with identical
> drives
> > > one motor ran hotter than the other.  Further investigation showed the
> > > resistance of the windings was different with the warmer motor having
> the
> > > lower resistance and inductance which matched the spec sheet.  By then
> it
> > > was too late to return the high resistance one so I decided to put what
> > > appeared to be the on spec motor on the Y axis since it had to carry
> more
> > > weight.  The X axis got the cooler and higher resistance motor.
> > >
> > > When I finally got it all together I had a lot of position errors and
> > > Henrik convinced me to trash the US Digital encoders which appeared to
> be
> > > losing counts and replace them with the CUI.  Changing to Henrik's
> module
> > > improved things and positioning was now reasonably accurate.  Until a
> short
> > > while ago on the X axis.
> > >
> > > I pulled the encoder off remounted things and the problem seemed to go
> > > away.  Well last week, after the center drilled holes were off from
> where
> > > the 1/4" drill bit went down I realized the problem had returned.
> After
> > > much mucking around it seems that the real issue is still with that X
> axis
> > > out of spec motor.
> > >
> > > What I did is swap motor+encoder from X <=> Y.  The cumulative position
> > > errors on X are now gone so that shows the HP_UHU drive was not the
> is

Re: [Emc-users] DC Servo issues

[John Figie]

John Figie


On Sun, Sep 19, 2021 at 2:07 PM John Dammeyer 
wrote:

>
>
> That's the question.  One possibility to try is to grab 110VAC line
> voltage. Put a bridge and caps on it and drive that motor with more than
> the 105VDC power supply.  I'll have to check if my transistors are rated
> for the 165VDC rectified voltage and I really would rather have them be
> 250V transitors.


I think you will need the 250V transistors and also need to consider a
shunt resistor and switch to keep the bus voltage from going too high when
you rapidly decelerate a motor.


> And then there's the filters on the board too. The UHU circuit was
> originally for up to about 75V.  The HP_UHU came about for higher voltage
> drives;  Just don't know if I built mine for more than 125VDC although the
> circuit design parts are for 11A.
>
> I _have_ tried one these motors with the STMBL but could never get it
> tuned and support from the designers was inadequate to help me so I gave
> up.
>
> I'd rather be machining...
>
> John
>
>
>

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Re: [Emc-users] DC Servo issues

[Sam Sokolik]

Lol..  I certainly love the electrics part more than the machining most of
the time...

On Sun, Sep 19, 2021, 2:07 PM John Dammeyer  wrote:

> Hi Sam,
> See below.
> > From: Sam Sokolik [mailto:samco...@gmail.com]
> >
> > I have never used servo drives that close the loop..   I have always had
> > great luck with normal closed loop within linuxcnc.  (cheap used amc
> > drives)
> >
> > (Actually - I take that back - I have used the stmbl drives. so far only
> > for a spindle..)
> >
> > This is of course using mesa analog interface hardware.
> >
> > The only time I had issues with encoder counting was when I thought I
> could
> > get by with single ended encoders going over 8 ft...
> >
> > Look at something like this..  2 counts per rev,  2 axis with 4000?
> > counts per rev...  (and the encoders came installed on the servo, single
> > ended and I think they are us-digital)
> > If I was missing counts during these complicated sync moves - you would
> > certainly see it.
> >
> > https://www.youtube.com/watch?v=-4sKHBh6rDk
> >
> > (plus no 3rd party software to tune...)  - Granted you have the drives
> and
> > are familiar with them - at what point do you give up?
> >
> > sam
>
> That's the question.  One possibility to try is to grab 110VAC line
> voltage. Put a bridge and caps on it and drive that motor with more than
> the 105VDC power supply.  I'll have to check if my transistors are rated
> for the 165VDC rectified voltage and I really would rather have them be
> 250V transitors.   And then there's the filters on the board too. The UHU
> circuit was originally for up to about 75V.  The HP_UHU came about for
> higher voltage drives;  Just don't know if I built mine for more than
> 125VDC although the circuit design parts are for 11A.
>
> I _have_ tried one these motors with the STMBL but could never get it
> tuned and support from the designers was inadequate to help me so I gave
> up.
>
> I'd rather be machining...
>
> John
>
>
>
> >
> > On Sun, Sep 19, 2021 at 12:59 PM John Dammeyer 
> > wrote:
> >
> > > Hi Rick,
> > > It may also have something to do with the DC Servo drive electronics.
> > > Although it's differential encoder signalling the design may have
> internal
> > > issues that are somewhat corrected by the Henk Olsson module.  I had
> both a
> > > small electrolytic and ceramic capacitors right by the US Digital
> encoders,
> > > which BTW, have been discontinued for a few years.  Perhaps that's why?
> > > Issues?
> > >
> > > I swapped the X and Y motor/encoder pair and sure enough the problem
> moved
> > > to the Y axis along with now only 120 IPM instead of 150 IPM.  Above
> that I
> > > get following errors.  Given that this motor has a higher winding
> > > resistance I'm going to guess it's not a 90VDC motor but is more
> likely a
> > > 180VDC motor that was shipped as a 90VDC.   Maybe the loading
> introduces
> > > noise in one direction that fools the quadrature encoder.  It's very
> > > strange that the following errors are only in one direction.
> > >
> > > At $145US plus shipping, since Automation Technologies won't replace
> it,
> > > I'm going to cast a new mounting plate for one of the slightly smaller
> > > 1.27NM Bergerda AC servos.  They were destined for the ball screw
> upgrade
> > > (and I'd ordered the wrong size thinking they were the same torque as
> the
> > > DC ones).  So we'll see.  If the Bergerda does well on the heavier Y
> axis
> > > then problem solved.
> > >
> > > More as it unfolds.
> > >
> > > Oh I swapped motor/encoder sets between X and Y,and with the Y motor
> > > running the X axis the test program that runs the table back and forth
> no
> > > longer has a slightly different sound between changing direction CW
> > > compared to CCW.  So it appears that's also on the motor and not
> LinuxCNC
> > > nor the MESA.  And absolutely no errors in position on X.  Only now on
> the
> > > Y instead.  That lets the HP_UHU servo drive off the hook too.
> > >
> > > John
> > >
> > > > -Original Message-
> > > > From: Rick Moscoloni [mailto:rmoscol...@gmail.com]
> > > > Sent: September-19-21 10:12 AM
> > > > To: Enhanced Machine Controller (EMC)
> > > > Subject: Re: [Emc-users] DC Servo issues
> > > >
> > > > us digi

Re: [Emc-users] DC Servo issues

[John Dammeyer]

Hi Sam,
See below.
> From: Sam Sokolik [mailto:samco...@gmail.com]
> 
> I have never used servo drives that close the loop..   I have always had
> great luck with normal closed loop within linuxcnc.  (cheap used amc
> drives)
> 
> (Actually - I take that back - I have used the stmbl drives. so far only
> for a spindle..)
> 
> This is of course using mesa analog interface hardware.
> 
> The only time I had issues with encoder counting was when I thought I could
> get by with single ended encoders going over 8 ft...
> 
> Look at something like this..  2 counts per rev,  2 axis with 4000?
> counts per rev...  (and the encoders came installed on the servo, single
> ended and I think they are us-digital)
> If I was missing counts during these complicated sync moves - you would
> certainly see it.
> 
> https://www.youtube.com/watch?v=-4sKHBh6rDk
> 
> (plus no 3rd party software to tune...)  - Granted you have the drives and
> are familiar with them - at what point do you give up?
> 
> sam

That's the question.  One possibility to try is to grab 110VAC line voltage. 
Put a bridge and caps on it and drive that motor with more than the 105VDC 
power supply.  I'll have to check if my transistors are rated for the 165VDC 
rectified voltage and I really would rather have them be 250V transitors.   And 
then there's the filters on the board too. The UHU circuit was originally for 
up to about 75V.  The HP_UHU came about for higher voltage drives;  Just don't 
know if I built mine for more than 125VDC although the circuit design parts are 
for 11A.

I _have_ tried one these motors with the STMBL but could never get it tuned and 
support from the designers was inadequate to help me so I gave up.

I'd rather be machining...

John



> 
> On Sun, Sep 19, 2021 at 12:59 PM John Dammeyer 
> wrote:
> 
> > Hi Rick,
> > It may also have something to do with the DC Servo drive electronics.
> > Although it's differential encoder signalling the design may have internal
> > issues that are somewhat corrected by the Henk Olsson module.  I had both a
> > small electrolytic and ceramic capacitors right by the US Digital encoders,
> > which BTW, have been discontinued for a few years.  Perhaps that's why?
> > Issues?
> >
> > I swapped the X and Y motor/encoder pair and sure enough the problem moved
> > to the Y axis along with now only 120 IPM instead of 150 IPM.  Above that I
> > get following errors.  Given that this motor has a higher winding
> > resistance I'm going to guess it's not a 90VDC motor but is more likely a
> > 180VDC motor that was shipped as a 90VDC.   Maybe the loading introduces
> > noise in one direction that fools the quadrature encoder.  It's very
> > strange that the following errors are only in one direction.
> >
> > At $145US plus shipping, since Automation Technologies won't replace it,
> > I'm going to cast a new mounting plate for one of the slightly smaller
> > 1.27NM Bergerda AC servos.  They were destined for the ball screw upgrade
> > (and I'd ordered the wrong size thinking they were the same torque as the
> > DC ones).  So we'll see.  If the Bergerda does well on the heavier Y axis
> > then problem solved.
> >
> > More as it unfolds.
> >
> > Oh I swapped motor/encoder sets between X and Y,and with the Y motor
> > running the X axis the test program that runs the table back and forth no
> > longer has a slightly different sound between changing direction CW
> > compared to CCW.  So it appears that's also on the motor and not LinuxCNC
> > nor the MESA.  And absolutely no errors in position on X.  Only now on the
> > Y instead.  That lets the HP_UHU servo drive off the hook too.
> >
> > John
> >
> > > -Original Message-
> > > From: Rick Moscoloni [mailto:rmoscol...@gmail.com]
> > > Sent: September-19-21 10:12 AM
> > > To: Enhanced Machine Controller (EMC)
> > > Subject: Re: [Emc-users] DC Servo issues
> > >
> > > us digital encoders with a capacitor across dc+and- works without a
> > > fault
> > >
> > > El dom, 19 sept 2021 a las 2:49, John Dammeyer ( > >)
> > > escribi?:
> > >
> > > > Over 10 years ago I bought two of these for the XY axis of the mill.
> > > >
> > > >
> > https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor
> > > >
> > > > Also from US Digital the 250 line encoders.
> > > > I had assembled HP_UHU kits and had on standby the Henrik Olsson
> > > > repl

Re: [Emc-users] DC Servo issues

[Sam Sokolik]

I have never used servo drives that close the loop..   I have always had
great luck with normal closed loop within linuxcnc.  (cheap used amc
drives)

(Actually - I take that back - I have used the stmbl drives. so far only
for a spindle..)

This is of course using mesa analog interface hardware.

The only time I had issues with encoder counting was when I thought I could
get by with single ended encoders going over 8 ft...

Look at something like this..  2 counts per rev,  2 axis with 4000?
counts per rev...  (and the encoders came installed on the servo, single
ended and I think they are us-digital)
If I was missing counts during these complicated sync moves - you would
certainly see it.

https://www.youtube.com/watch?v=-4sKHBh6rDk

(plus no 3rd party software to tune...)  - Granted you have the drives and
are familiar with them - at what point do you give up?

sam

On Sun, Sep 19, 2021 at 12:59 PM John Dammeyer 
wrote:

> Hi Rick,
> It may also have something to do with the DC Servo drive electronics.
> Although it's differential encoder signalling the design may have internal
> issues that are somewhat corrected by the Henk Olsson module.  I had both a
> small electrolytic and ceramic capacitors right by the US Digital encoders,
> which BTW, have been discontinued for a few years.  Perhaps that's why?
> Issues?
>
> I swapped the X and Y motor/encoder pair and sure enough the problem moved
> to the Y axis along with now only 120 IPM instead of 150 IPM.  Above that I
> get following errors.  Given that this motor has a higher winding
> resistance I'm going to guess it's not a 90VDC motor but is more likely a
> 180VDC motor that was shipped as a 90VDC.   Maybe the loading introduces
> noise in one direction that fools the quadrature encoder.  It's very
> strange that the following errors are only in one direction.
>
> At $145US plus shipping, since Automation Technologies won't replace it,
> I'm going to cast a new mounting plate for one of the slightly smaller
> 1.27NM Bergerda AC servos.  They were destined for the ball screw upgrade
> (and I'd ordered the wrong size thinking they were the same torque as the
> DC ones).  So we'll see.  If the Bergerda does well on the heavier Y axis
> then problem solved.
>
> More as it unfolds.
>
> Oh I swapped motor/encoder sets between X and Y,and with the Y motor
> running the X axis the test program that runs the table back and forth no
> longer has a slightly different sound between changing direction CW
> compared to CCW.  So it appears that's also on the motor and not LinuxCNC
> nor the MESA.  And absolutely no errors in position on X.  Only now on the
> Y instead.  That lets the HP_UHU servo drive off the hook too.
>
> John
>
> > -Original Message-----
> > From: Rick Moscoloni [mailto:rmoscol...@gmail.com]
> > Sent: September-19-21 10:12 AM
> > To: Enhanced Machine Controller (EMC)
> > Subject: Re: [Emc-users] DC Servo issues
> >
> > us digital encoders with a capacitor across dc+and- works without a
> > fault
> >
> > El dom, 19 sept 2021 a las 2:49, John Dammeyer ( >)
> > escribi�:
> >
> > > Over 10 years ago I bought two of these for the XY axis of the mill.
> > >
> > >
> https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor
> > >
> > > Also from US Digital the 250 line encoders.
> > > I had assembled HP_UHU kits and had on standby the Henrik Olsson
> > > replacement PIC processor modules although this photo shows the
> original
> > > processor.
> > > http://www.autoartisans.com/mill/HP_UHU_Modified.jpg
> > >
> > > One of the things that showed up right away was that with identical
> drives
> > > one motor ran hotter than the other.  Further investigation showed the
> > > resistance of the windings was different with the warmer motor having
> the
> > > lower resistance and inductance which matched the spec sheet.  By then
> it
> > > was too late to return the high resistance one so I decided to put what
> > > appeared to be the on spec motor on the Y axis since it had to carry
> more
> > > weight.  The X axis got the cooler and higher resistance motor.
> > >
> > > When I finally got it all together I had a lot of position errors and
> > > Henrik convinced me to trash the US Digital encoders which appeared to
> be
> > > losing counts and replace them with the CUI.  Changing to Henrik's
> module
> > > improved things and positioning was now reasonably accurate.  Until a
> short
> > > while ago on the X axis.
> > >
> > &

Re: [Emc-users] DC Servo issues

[John Dammeyer]

Hi Rick,
It may also have something to do with the DC Servo drive electronics.  Although 
it's differential encoder signalling the design may have internal issues that 
are somewhat corrected by the Henk Olsson module.  I had both a small 
electrolytic and ceramic capacitors right by the US Digital encoders, which 
BTW, have been discontinued for a few years.  Perhaps that's why?  Issues?

I swapped the X and Y motor/encoder pair and sure enough the problem moved to 
the Y axis along with now only 120 IPM instead of 150 IPM.  Above that I get 
following errors.  Given that this motor has a higher winding resistance I'm 
going to guess it's not a 90VDC motor but is more likely a 180VDC motor that 
was shipped as a 90VDC.   Maybe the loading introduces noise in one direction 
that fools the quadrature encoder.  It's very strange that the following errors 
are only in one direction.  

At $145US plus shipping, since Automation Technologies won't replace it, I'm 
going to cast a new mounting plate for one of the slightly smaller 1.27NM 
Bergerda AC servos.  They were destined for the ball screw upgrade (and I'd 
ordered the wrong size thinking they were the same torque as the DC ones).  So 
we'll see.  If the Bergerda does well on the heavier Y axis then problem 
solved.   

More as it unfolds.  

Oh I swapped motor/encoder sets between X and Y,and with the Y motor running 
the X axis the test program that runs the table back and forth no longer has a 
slightly different sound between changing direction CW compared to CCW.  So it 
appears that's also on the motor and not LinuxCNC nor the MESA.  And absolutely 
no errors in position on X.  Only now on the Y instead.  That lets the HP_UHU 
servo drive off the hook too.

John

> -Original Message-
> From: Rick Moscoloni [mailto:rmoscol...@gmail.com]
> Sent: September-19-21 10:12 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] DC Servo issues
> 
> us digital encoders with a capacitor across dc+and- works without a
> fault
> 
> El dom, 19 sept 2021 a las 2:49, John Dammeyer ()
> escribi�:
> 
> > Over 10 years ago I bought two of these for the XY axis of the mill.
> >
> > https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor
> >
> > Also from US Digital the 250 line encoders.
> > I had assembled HP_UHU kits and had on standby the Henrik Olsson
> > replacement PIC processor modules although this photo shows the original
> > processor.
> > http://www.autoartisans.com/mill/HP_UHU_Modified.jpg
> >
> > One of the things that showed up right away was that with identical drives
> > one motor ran hotter than the other.  Further investigation showed the
> > resistance of the windings was different with the warmer motor having the
> > lower resistance and inductance which matched the spec sheet.  By then it
> > was too late to return the high resistance one so I decided to put what
> > appeared to be the on spec motor on the Y axis since it had to carry more
> > weight.  The X axis got the cooler and higher resistance motor.
> >
> > When I finally got it all together I had a lot of position errors and
> > Henrik convinced me to trash the US Digital encoders which appeared to be
> > losing counts and replace them with the CUI.  Changing to Henrik's module
> > improved things and positioning was now reasonably accurate.  Until a short
> > while ago on the X axis.
> >
> > I pulled the encoder off remounted things and the problem seemed to go
> > away.  Well last week, after the center drilled holes were off from where
> > the 1/4" drill bit went down I realized the problem had returned.  After
> > much mucking around it seems that the real issue is still with that X axis
> > out of spec motor.
> >
> > What I did is swap motor+encoder from X <=> Y.  The cumulative position
> > errors on X are now gone so that shows the HP_UHU drive was not the issue.
> > What's really interesting is the heavier Y axis now regularly faults at 140
> > ipm where before the other motor could do 150 ipm.
> >
> > Also interesting when I drop the speeds to below 130 it doesn't fault but
> > I started seeing position errors.
> >
> > The G-Code test program
> > G01 X0 Y0 F60
> > X-4
> > Y-1.1
> > Y0
> > X0
> > Y-1.1
> > Y0
> > X5
> > And so on for about 5 cycles.
> >
> > Now the X axis returns to 0 every single time from either side of 0.  But
> > the Y axis accumulates -0.020 or so error every time the program runs just
> > like X used to with that motor.  Always only negative values.  So strange.

Re: [Emc-users] DC Servo issues

[Rick Moscoloni]

us digital encoders with a capacitor across dc+and- works without a
fault

El dom, 19 sept 2021 a las 2:49, John Dammeyer ()
escribió:

> Over 10 years ago I bought two of these for the XY axis of the mill.
>
> https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor
>
> Also from US Digital the 250 line encoders.
> I had assembled HP_UHU kits and had on standby the Henrik Olsson
> replacement PIC processor modules although this photo shows the original
> processor.
> http://www.autoartisans.com/mill/HP_UHU_Modified.jpg
>
> One of the things that showed up right away was that with identical drives
> one motor ran hotter than the other.  Further investigation showed the
> resistance of the windings was different with the warmer motor having the
> lower resistance and inductance which matched the spec sheet.  By then it
> was too late to return the high resistance one so I decided to put what
> appeared to be the on spec motor on the Y axis since it had to carry more
> weight.  The X axis got the cooler and higher resistance motor.
>
> When I finally got it all together I had a lot of position errors and
> Henrik convinced me to trash the US Digital encoders which appeared to be
> losing counts and replace them with the CUI.  Changing to Henrik's module
> improved things and positioning was now reasonably accurate.  Until a short
> while ago on the X axis.
>
> I pulled the encoder off remounted things and the problem seemed to go
> away.  Well last week, after the center drilled holes were off from where
> the 1/4" drill bit went down I realized the problem had returned.  After
> much mucking around it seems that the real issue is still with that X axis
> out of spec motor.
>
> What I did is swap motor+encoder from X <=> Y.  The cumulative position
> errors on X are now gone so that shows the HP_UHU drive was not the issue.
> What's really interesting is the heavier Y axis now regularly faults at 140
> ipm where before the other motor could do 150 ipm.
>
> Also interesting when I drop the speeds to below 130 it doesn't fault but
> I started seeing position errors.
>
> The G-Code test program
> G01 X0 Y0 F60
> X-4
> Y-1.1
> Y0
> X0
> Y-1.1
> Y0
> X5
> And so on for about 5 cycles.
>
> Now the X axis returns to 0 every single time from either side of 0.  But
> the Y axis accumulates -0.020 or so error every time the program runs just
> like X used to with that motor.  Always only negative values.  So strange.
>
> Also when that motor was on the X axis the sound of the system when
> changing direction was clunky sounding in one direction and not the other
> under G-Code.  The change direction with jogging keys wasn't like that.
>
> I don't think it's worthwhile to spend the time to figure out what's
> wrong.  Seems pointless to continue to use a motor that isn't up to spec.
> Probably better to just install one of the Bergerda AC Servos I have here
> that I was saving for the Ball Screw upgrade.  Especially since
> AutomationTechnologies wouldn't replace the motor even though it was
> clearly out of spec.  Not about to buy anything else from them.
>
> John Dammeyer
>
>
>
>
> ___
> Emc-users mailing list
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> https://lists.sourceforge.net/lists/listinfo/emc-users
>

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Re: [Emc-users] DC Servo issues

[Bari]

On 9/19/21 00:44, John Dammeyer wrote:


Over 10 years ago I bought two of these for the XY axis of the mill.
https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor



One of the things that showed up right away was that with identical drives one 
motor ran hotter than the other.  Further investigation showed the resistance 
of the windings was different with the warmer motor having the lower resistance 
and inductance which matched the spec sheet.  By then it was too late to return 
the high resistance one so I decided to put what appeared to be the on spec 
motor on the Y axis since it had to carry more weight.  The X axis got the 
cooler and higher resistance motor.
Especially since AutomationTechnologies wouldn't replace the motor even though 
it was clearly out of spec.  Not about to buy anything else from them.



They are local for me. The owner is a nice enough guy but he also 
problems with getting reliable consistent parts from his homeland.


I only buy things from them that I expect to be like a kit that needs to 
be cleaned and assembled properly before use. I have had to return 
radial bearings with detents and linear bearings with crud inside or 
flat spots. We call them crunchy bearings. CNC mills come with red oxide 
treated fasteners and without nuts on the end of ballscrews so you can't 
adjust preloads unless you shim or replace with proper screws. Cables 
are assembled without the use of strain reliefs.


Red oxide treated fasteners  https://postimg.cc/jnhmsRhq

No strain relief  https://postimg.cc/7bqwTvvy

1mm of lash  https://postimg.cc/w1bvqpWk




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[Emc-users] DC Servo issues

[John Dammeyer]

Over 10 years ago I bought two of these for the XY axis of the mill. 
https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor

Also from US Digital the 250 line encoders.
I had assembled HP_UHU kits and had on standby the Henrik Olsson replacement 
PIC processor modules although this photo shows the original processor.
http://www.autoartisans.com/mill/HP_UHU_Modified.jpg

One of the things that showed up right away was that with identical drives one 
motor ran hotter than the other.  Further investigation showed the resistance 
of the windings was different with the warmer motor having the lower resistance 
and inductance which matched the spec sheet.  By then it was too late to return 
the high resistance one so I decided to put what appeared to be the on spec 
motor on the Y axis since it had to carry more weight.  The X axis got the 
cooler and higher resistance motor.

When I finally got it all together I had a lot of position errors and Henrik 
convinced me to trash the US Digital encoders which appeared to be losing 
counts and replace them with the CUI.  Changing to Henrik's module improved 
things and positioning was now reasonably accurate.  Until a short while ago on 
the X axis.

I pulled the encoder off remounted things and the problem seemed to go away.  
Well last week, after the center drilled holes were off from where the 1/4" 
drill bit went down I realized the problem had returned.  After much mucking 
around it seems that the real issue is still with that X axis out of spec motor.

What I did is swap motor+encoder from X <=> Y.  The cumulative position errors 
on X are now gone so that shows the HP_UHU drive was not the issue.  What's 
really interesting is the heavier Y axis now regularly faults at 140 ipm where 
before the other motor could do 150 ipm. 

Also interesting when I drop the speeds to below 130 it doesn't fault but I 
started seeing position errors.

The G-Code test program
G01 X0 Y0 F60
X-4
Y-1.1
Y0
X0 
Y-1.1
Y0
X5
And so on for about 5 cycles.

Now the X axis returns to 0 every single time from either side of 0.  But the Y 
axis accumulates -0.020 or so error every time the program runs just like X 
used to with that motor.  Always only negative values.  So strange.

Also when that motor was on the X axis the sound of the system when changing 
direction was clunky sounding in one direction and not the other under G-Code.  
The change direction with jogging keys wasn't like that.  

I don't think it's worthwhile to spend the time to figure out what's wrong.  
Seems pointless to continue to use a motor that isn't up to spec.  Probably 
better to just install one of the Bergerda AC Servos I have here that I was 
saving for the Ball Screw upgrade.  Especially since AutomationTechnologies 
wouldn't replace the motor even though it was clearly out of spec.  Not about 
to buy anything else from them.  

John Dammeyer




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