Re: [Emc-users] Assembled control cabinet

[Gene Heskett]

On Saturday 13 February 2021 18:35:40 John Dammeyer wrote:

> > -Original Message-
> > From: marcus.bow...@visible.eclipse.co.uk
> >
> > On 2021-02-13 18:10, John Dammeyer wrote:
> > > Friday night I put everything back onto the mill to make sure that
> > > with all the cabinetry and wiring changes (including a new Knee
> > > Motor) that I hadn't broken anything.
> > >
> > > Everything works as this video demonstrates.
> > > https://youtu.be/I6lvnYhlez4
> >
> > Nice demo, and impressive speeds.
> >
> > What is the max speed of the spindle?
> >
> > Marcus
>
> The 3 pulley combination with single phase motor was 2950 RPM and from
> what I've read you don't really want to push the stock bearings past
> that.
>
> The Bergerda 1.8kW Servo is 3000 RPM with two custom pulleys for 1:1. 
> I can also get about 1.5:1 with a slightly different pulley set to
> increase torque at lower speeds if I need it.  So far with what I've
> done I've not seen major loading.  I'm using PWM to a small far easy
> 0V to 10V module which limits low speed to 100RPM and does go to 3000
> RPM.
>
> When I had the setup on the bench this week I ran a motor with
> step/dir instead of PWM.  Easy with MACH3 because you just change a
> check box for PWM (1kHz)  or STEP with appropriate tuning for max RPM.
>  At the moment impossible using the MESA 7i92H without running
> different wires from the second parallel port.  Or going through the
> process of reprogramming the existing PWM pins to have a step/dir
> module instead which I don't know how to do.  Be nice if the FPGA
> firmware had a few parameters that could be set from the HAL file to
> select either PWM or Step/Dir.  I'm using the stock MESA
> 7i92_C11Gx2D.pin file.
>
The software pwmgen and the mesa pwmgen have both step/dir and individual 
dir steps in mode=2, where it pulses one wire or the other, this can 
drive a full bridge driver from the bob's 2 outputs.

What I don't know is if your bergera drives can handle that style of 
signal,

My home made servo is using these mode 2 signals straight into a $6.40 
BTS 7960 dual half bridge. Its rated for 27 volts, at up to 43 amps, 
develops absolutely no heat running a 24 volt 100 watt motor with a worm 
output, from a 400 watt, 24 volt psu, which is driveing the worm of a 
BS-1 at about 2 to 3 rpm at the chuck to an accuracy of about .0003 
degrees. The ONLY failures I have had was when it was running wide open 
and I sent it a reverse, that will crowbar the 400 watt supply and shut 
it down for a couple minutes to cool, no smoke was let out and no 
kittens were killed.

Cycle the power after the psu fan quits blowing hot air and its ready to 
do it again.

> The technique for stepping under WIN-XP parallel port does create
> considerable jitter and inaccuracies.  I found when I set up to create
> a step rate for 3000 RPM after 20 or so seconds the servo would fault
> with a following error.  The motor itself is limited to 3000 RPM so if
> you exceed that step rate then eventually it can't keep up.
>
> Setting the step rate to give me 2980 RPM (as indicated on the
> Bergerda LED display) no longer created the following error.  I could
> probably tweak it closer.  I did not try moving the USB SmoothStepper
> over from the CNC router to see if it was more stable.  Don't care
> really.  I seem to boot into LinuxCNC more often then MACH3.
>
> Under LinuxCNC I expect with the MESA once I've assigned HAL Pins
> configured to use one of the step/dir modules that the step rate for
> 3000 RPM will be very precise. But even then I'm probably best to aim
> for 2950 RPM.
>
> Oh and I think the other reason it wouldn't be a good idea to go above
> manufacturers recommended 2950 RPM is that when I tighten the quill
> clamp the bearing noise in the spindle changes.   I don't know if
> other mills do this but it's certainly not encouraging.
>
I have not noted such an effect on my ultra cheap GO704. I wouldn't be 
encouraged either.

Stay well John

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] Assembled control cabinet

[John Dammeyer]

> -Original Message-
> From: marcus.bow...@visible.eclipse.co.uk 
> On 2021-02-13 18:10, John Dammeyer wrote:
> > Friday night I put everything back onto the mill to make sure that
> > with all the cabinetry and wiring changes (including a new Knee Motor)
> > that I hadn't broken anything.
> >
> > Everything works as this video demonstrates.
> > https://youtu.be/I6lvnYhlez4
> >
> 
> Nice demo, and impressive speeds.
> 
> What is the max speed of the spindle?
> 
> Marcus
The 3 pulley combination with single phase motor was 2950 RPM and from what 
I've read you don't really want to push the stock bearings past that.  

The Bergerda 1.8kW Servo is 3000 RPM with two custom pulleys for 1:1.  I can 
also get about 1.5:1 with a slightly different pulley set to increase torque at 
lower speeds if I need it.  So far with what I've done I've not seen major 
loading.  I'm using PWM to a small far easy 0V to 10V module which limits low 
speed to 100RPM and does go to 3000 RPM.

When I had the setup on the bench this week I ran a motor with step/dir instead 
of PWM.  Easy with MACH3 because you just change a check box for PWM (1kHz)  or 
STEP with appropriate tuning for max RPM.  At the moment impossible using the 
MESA 7i92H without running different wires from the second parallel port.  Or 
going through the process of reprogramming the existing PWM pins to have a 
step/dir module instead which I don't know how to do.  Be nice if the FPGA 
firmware had a few parameters that could be set from the HAL file to select 
either PWM or Step/Dir.  I'm using the stock MESA 7i92_C11Gx2D.pin file.

The technique for stepping under WIN-XP parallel port does create considerable 
jitter and inaccuracies.  I found when I set up to create a step rate for 3000 
RPM after 20 or so seconds the servo would fault with a following error.  The 
motor itself is limited to 3000 RPM so if you exceed that step rate then 
eventually it can't keep up.

Setting the step rate to give me 2980 RPM (as indicated on the Bergerda LED 
display) no longer created the following error.  I could probably tweak it 
closer.  I did not try moving the USB SmoothStepper over from the CNC router to 
see if it was more stable.  Don't care really.  I seem to boot into LinuxCNC 
more often then MACH3.

Under LinuxCNC I expect with the MESA once I've assigned HAL Pins configured to 
use one of the step/dir modules that the step rate for 3000 RPM will be very 
precise. But even then I'm probably best to aim for 2950 RPM. 

Oh and I think the other reason it wouldn't be a good idea to go above 
manufacturers recommended 2950 RPM is that when I tighten the quill clamp the 
bearing noise in the spindle changes.   I don't know if other mills do this but 
it's certainly not encouraging.

John




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Re: [Emc-users] Assembled control cabinet

[marcus . bowman]

On 2021-02-13 18:10, John Dammeyer wrote:

Friday night I put everything back onto the mill to make sure that
with all the cabinetry and wiring changes (including a new Knee Motor)
that I hadn't broken anything.

Everything works as this video demonstrates.
https://youtu.be/I6lvnYhlez4



Nice demo, and impressive speeds.

What is the max speed of the spindle?

Marcus


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[Emc-users] Assembled control cabinet

[John Dammeyer]

Friday night I put everything back onto the mill to make sure that with all the 
cabinetry and wiring changes (including a new Knee Motor) that I hadn't broken 
anything.
 
Everything works as this video demonstrates.  
https://youtu.be/I6lvnYhlez4
The knee motion is 150 ipm which is really too fast for the bevel gears and 
they are very noisy.  Going down the motor is faster than what gravity does to 
the knee mass and so the knee appears to catch up and then be pulled and then 
catch up and be pulled.
 
But even at that speed the Bergerda Servo does not fault so that's good.  The 
3D printed gears are 3.2:1 turning the 0.25" per turn knee handle.  I think 
I'll limit knee top speed to about 60 or 80 ipm.   Sure is nicer than the 24 
ipm I had with the 1200 oz-in stepper motor.  At 24 ipm this AC servo and the 
knee are very quiet.
 
Now to still figure out what to do with the combined Fault signal.
 
John
 
 
"ELS! Nothing else works as well for your Lathe"
Automation Artisans Inc.
www dot autoartisans dot com 
 

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