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Author Topic: Motors stalling /growling  (Read 1815 times)

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Re: Motors stalling /growling
« Reply #10 on: May 04, 2019, 09:03:39 PM »
Made changes on driver switches but did not solve the growling/stalling. May be I just need to find tune the motors. Any suggestion are welcome?

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Re: Motors stalling /growling
« Reply #11 on: May 04, 2019, 11:30:44 PM »
Made changes on driver switches but did not solve the growling/stalling. May be I just need to find tune the motors. Any suggestion are welcome?
see attached (mm units) as starting point. Then tune up by making changes to suit your hardware.
If you have a fast PC, step pulse could be decreased to 5 or even 2. Decrease until SMOOTH.

increase speed and accel for each axis until it's becomes too high then back off 20% for normal use.
« Last Edit: May 04, 2019, 11:35:44 PM by reuelt »
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Re: Motors stalling /growling
« Reply #12 on: May 05, 2019, 08:15:20 AM »
should my drivers never be set above 1600 steps per rev. ?? And than set accordingly?
Re: Motors stalling /growling
« Reply #13 on: May 05, 2019, 03:02:09 PM »
Hi,
it is possible to set your microstepping regime higher than 8 microsteps per full step (1600 steps per rev)
but you get little advantage.

It is seductive to believe that you get increased resolution as the number of microsteps go up, unfortunately
that does not happen in practice. In fact no genuine increase in resolution is achieved beyond half stepping (400
steps per rev). If no increase in resolution then why bother? The answer is smoothness of motion....the higher the
microstepping the smoother the motion.

If however you increase the microstepping too high then the required pulse rate to spin your motors will exceed what your
controller is capable of.

For example if you set your microstepping to 64 microsteps per fullstep (12800 steps per rev) and you want a maximum
speed of 600rpm from your stepper the required pulse rate is:

600 / 60 =10 (revs/sec)
Pulse rate =10 x 12800
              =128kHz

Machs parallel port in default is only 25kHz and there are only a few external controllers that can generate pulse stream at that
speed. If however you choose 8 microsteps per fullstep the pulse rate is:
600 / 60 =10 (revs/sec)
Pulse rate = 10 X 1600
               =16kHz

ie well within Machs parallel port even at default speed.

As it turns out the smoothness of an 8 microstep regime is very nearly the same as a 16 or 32 microstep regime
ie there is little to be gained beyond 8 microsteps (1600 steps/rev). As a consequence 4, 5, 8 and 10 microsteps
per fullstep are the norm among Mach CNCers.

Craig
My wife left with my best friend...
     and I miss him!

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Re: Motors stalling /growling
« Reply #14 on: May 05, 2019, 05:33:56 PM »
should my drivers never be set above 1600 steps per rev. ?? And than set accordingly?
Craig already said it well.
See attached and ask yourself.
Do I want to lose more "holding torque" by setting micro-steps much higher?
Holding torque.
A stepper motor's holding torque is the amount of torque needed in order to move the motor one full step when the windings are energized but the rotor is stationary
More holding torque is needed if you want to cut MORE deeper in one pass.
« Last Edit: May 05, 2019, 05:50:30 PM by reuelt »
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Re: Motors stalling /growling
« Reply #15 on: May 05, 2019, 07:15:06 PM »
Also see attached (result published at Hackaday)
Highest accuracy is 1/8 microsteps (1600 microsteps/rev)
Above 1/16 microsteps (3200 microsteps/rev) stepper motor can no longer position accurately.
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Re: Motors stalling /growling
« Reply #16 on: May 05, 2019, 08:27:37 PM »
in motor tuning I have set my/ steps per, to 1600/ and I have changed my velocity and acceleration to many different numbers. I can get the motors to run smooth when I jog, but when running the demo in mach 3 they sound terrible. At this point I am not worry about speed. I just can't get them tuned. I know i'm just missing something but can't figure it out. I don't give up very easy so i'll keep at it. So any information on tuning is appreciated. you need to dummy it down, as I said I am very new. Thanks for all your information.

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Re: Motors stalling /growling
« Reply #17 on: May 06, 2019, 01:47:11 AM »
in motor tuning I have set my/ steps per, to 1600/ and I have changed my velocity and acceleration to many different numbers. I can get the motors to run smooth when I jog, but when running the demo in mach 3 they sound terrible. At this point I am not worry about speed. I just can't get them tuned. I know i'm just missing something but can't figure it out. I don't give up very easy so i'll keep at it. So any information on tuning is appreciated. you need to dummy it down, as I said I am very new. Thanks for all your information.

steps/per are not set to steps per motorrevolution it is steps/unit (mm or Inch, dont know in witch Units you are working).

do you realy have 1600 steps per mm or Inch?
are you realy sure about your Motor Connections (A+/A- and B+/B-)?
witch exact Motors are you using?
« Last Edit: May 06, 2019, 01:51:09 AM by TPS »
anything is possible, just try it.
if you find some mistakes, in my bad bavarian english,they are yours.
Re: Motors stalling /growling
« Reply #18 on: May 06, 2019, 03:38:37 AM »
Hi,

Quote
I can get the motors to run smooth when I jog, but when running the demo in mach 3 they sound terrible.

First lets dispel a myth, Mach3 Demo and Licensed Mach3 run identically. The only limitation that need concern you is that Demo
is limited to 500 lines of Gcode at a time. The kernel frequency of Mach3 Demo is limited to 25Hz, but this need not concern you,
unless, as previously explained, you choose to set a too higher microstepping regime; if you keep to 8 microsteps per full step
or below the limited kernel speed will have no effect.

The fact that the motors run smoothly when jogging tells us that the steppers and drivers are good, it also tells us that the BoB
and Machs parallel port can produce the required high quality pulse stream. The fact that the same steppers/drivers/BoB run poorly
when processing code suggests to me that Mach's parallel port is running poorly when the Gcode interpreter is commanding
motion.

My guess is that when the Gcode interpreter is running it introduces a heavy demand on the PC's interrupt system which in
turn causes excessive jitter within Mach's parallel port driver, itself an interrupt driven timer.

Proving that this is so is not straight forward.

Would you please post a screen shot of DriverTest.exe. Its not conclusive but is still a fair indication as to the health or
otherwise of the parallel port driver. Note that some PC's seem to do a good job with a parallel port and another machine,
possibly with much higher specification, does poorly. There is no way to tell short of installing Mach and trying it.

Have you considered an external motion controller such as an Ethernet SmoothStepper or a UC300? One of the
advantages that an external motion controller offers (vs the parallel port) is very high quality, high speed pulse
streams WITHOUT being dependent on PC hardware. Should you consider this option you should budget somewhere
in the $150-$300 range, if you buy cheap Chinese rubbish you'll have even less luck with it than the parallel port!!!

Craig
My wife left with my best friend...
     and I miss him!

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Re: Motors stalling /growling
« Reply #19 on: May 06, 2019, 04:08:22 AM »
Perhaps speed (in motor tuning) is set too high so G0 moves in program run are stalling /growling

Jog may appear Ok because the MACH3 Factory default Jog speed is at 50% (unless it had been changed by user).
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