Stepper motor stutters.

[Sinistersam]

I am having a problem with my motors and/or drivers. The best way to describe it would be to listen to it yourself, so I recorded it. http://sinistersam.com/del/motor.mp3
Every so often, they will have stutters. Some times these 'stutters' will be strong enough to cause it to stop turning. I have tried using a different computer. I have tried using different motors. Same problem. I have 3 G203V's (geckos), and this problem occurs on 2 of them. One drive runs smoothly. If I simply swap the drive, leaving the wiring the same, the motor runs smoothly. So I am assuming now that the problem is with the drivers.
Am I correct in this assumption?
What is the cause of this problem?
What is the remedy?
Thank you for any replies.

This post was posted in another forum also with these replies so far....

Is this under Mach3? Sounds like a disturbed timer by another process.

1) Use a breakout board from Bob Campbell Designs, PMDX or CNC4PC.
These boards convert the 3.3V logic from your parallel port to 5V
logic the G320 needs.

2) Set Mach3 ports and pins to 'active low' on all outputs. Set Mach3
motor tuning 'step pulse width' to '3uS'.

3) Run a wire from your motor case to terminal 1 (GND) of the G320.
Have this wire in the same cable with the 2 motor armature wires.

4) Use twisted pair cable for long encoder cable runs (> 10 ft or 3
m). Put CH_A and GND on one pair, CH_B and +5VDC on another pair.
Never put CH_A and CH_B on the same twisted pair.

5) Do not bundle the motor cable with the encoder cable unless both
cables are shielded. Ground the shield at one end only, usually at
the control box end.

Thanks for the replies. Unfortunatly, the problem still remains.

Yes it is under mach3. However, the problem is also present under turbocnc.
Fresh format and install of XP, and also DOS on another partition for turbocnc.

The drives are 203V's. I was under the impression that the 203's did'nt need the breakout board. All I'm using is a 25 pin cable to terminal block board. I think you must have misinterpreted my post for having 320's. The motor is wired directly to the drive, to take the long cable out of the equation. The wires are about 10 inches long. If I simply take the terminal blocks off the drive, and swap the drive out, the problem disappears completly. The stuttering only occurs on two of the three drives.

I am using a regulated switching type power supply @ 40V 7.5A. Could this type of supply damage the drive? This same problem has been posted on CNCZone. ( http://www.cnczone.com/forums/showth...6370&page=4and )The user also posted a sound clip, wich mimics my problem exactly. http://www.geocities.com/maglight2000us/motor_sound.mp3 . HOWEVER......his resolve to the problem was the breakout board, and he stated that when he bypassed it, everything worked fine.

The user base seems to be much larger here, hence the repost from another forum. Any ideas guys???

[kreutz]

Do you have access to one oscilloscope? Check the power supply output with the scope while your motors are working.

[Sinistersam]

Unfortunately I don't have access to one. I will try to find another supply and see if that remedies anything. Thank you for taking the time to post.

[kreutz]

Get two 4700 uF / 50 Volt capacitors in parallel and place them across the output from the power supply, for testing only , if the sound changes or disappears let me know. Next step is using two 25 ohm 50 watt resistors in series (to form the equivalent of one 50 ohm 100 watt) across the power supply (in order to drain approx 1 A continuously from it), and repeat the test with the motors.

[Sinistersam]

No change whatsoever.

[kreutz]

I was trying to rule out the switching power supply as the cause of the problem. By adding a continuous load you rule out the switching off of the PWM drivers when the load decreases as a result of regeneration or BEMF. By adding extra capacitance I was trying to rule out interference due to high frequency switching on the power supply interacting with high frequency chopping on the controller boards and producing beating frequencies in the audio spectrum.