Stepper running rough

[DAlgie]

Hi, my 13 by 40 Mach controlled lathe has an issue with it's X axis motor. It sounded like a bearing was going out on it or the ballscrew. It has a 1:2 drive belt up to the cross slide, so I removed the belt and rotated the screw by hand. It felt good. The motor also felt normal. I ran the motor by itself with the belt off and at higher speeds it sounded rough. I wondered if the stepper had lost a segment or something, don't know if they can do that. I had a new spare motor so I swapped it, and it was the same. Seems like it's missing steps with the rough sound, sort of intermittent, but I'm not sure. I had changed nothing before this, have just run the snot out of the thing the last few months. It also sounds rough at slow speeds, even with the belt drive off, so it's not loaded. I tried lowering the max speed, it did nothing, and why would it when the motor sounds abnormal at slower speeds anyway. Possible for a Gecko drive to go bad? Have 201's I believe or something like that, have great cooling on them.
   DaveA.

[OCNC]

Can you swap the drive with another axis to eliminate that as the problem?

Chris

[RICH]

If swapping the drives dosen't help then may want to have a look at the drive input signal from the computer.
NOT THE DRIVE OUTPUT AS YOU CAN BLOW THE DRIVE! You can also try adjusting the mid band adjusting trim pot or disabling it.

RICH

[DAlgie]

Thanks guys. I'll try playing with the mid band trim and see if that makes a difference, if not then swap the drive for the other axis.

DaveA.

[DAlgie]

Well I "fixed" it. I had a USB thumb drive plugged in, it has a flashing LED on it, wondered if that might be something messing with timing. So I uplugged it and the motor sounded good. I opened up the Driver test and ran it, the line was perfectly flat. While still running I plugged the USB drive in, and the line went fuzzy. Also had a small spike every 0.2 sec or somewhere like that. So, chalk that one up to experience I guess.

[RICH]

DAlgie,
Glad you found it. I often say that one should not "Play with Their Mouse" since that can create spikes during the driver test. Mach shares  time with Windows and anything which requires Windows to access a device can create problems. That is one of the reasons  I quit using a USB optical keyboard and mouse. Guess we can add a thumb drive to the list.

RICH

[olf20]

Rich, what do you use instead of your keyboard and mouse??
Thanks
olf20 / Bob

[RICH]

Serial port keyboard and mouse......tried mind control but kept falling asleep.     
RICH

[olf20]

I know what you mean.
Thanks olf20 / Bob