[Scott Pancheau]

I have a travel issue on one axis of a gantry with a 320 gecko. I can tune the travel distance in one direction to be spot on. When commanded the same distance in the opposite direction there is a gain of about a half inch in 36 inches.This remains constant so that there is additional gain every command. I have tried three different encoders and three different gecko drives and get the same problem with all. The Gecko thinks it is traveling correctly as is does not trip out when driving the incorrect distance. This is run by mach 3. The DRO shows the correct commanded travel. If I reinstall the original stepper motor with the same commands the travel is correct in both directions. The current encoder is a 600ppr incremental. The other two were an optical and a magnetic. I called gecko tech support and they suggested mechanical slip issues. I have checked that out and find no problem with slippage, and it is disproved by the stepper traveling correctly. I need more power than the stepper can deliver. Is there a test method I can employ to find the culprit?
Thanks for any suggestions.

Scott

[jfong]

I run a whole bunch of 320's. never seen one go different distances in opposite direction like that. The only thing I can think of is the step pulse width may be to short. Try increasing the step pulse width in mach3 tuning.

[Scott Pancheau]

Thanks for the suggestion. I will give it a try.

[Scott Pancheau]

I tried changing the setting gradually up the the 5 maximum and it did not change the error issue. If I run a program to cut a round hole it ends up as an oval. Short of an answer to the problem I will go back to stepper on that axis. Is there any possibility of it being a servo motor problem? It is a new old stock unit.

[jfong]

Swap servo motors with a different axis. See if the problem moves with the motor. If it does, motor is bad somehow.

[davy182]

Redo your connectors at the motor. We had something similar it was a bad connector.

[Scott Pancheau]

Thanks for your suggestions, I will try them tonight.

[Scott Pancheau]

I had no luck figuring out the cause. I reinstalled a stepper for now and it works as it should.