What i thought was mechanical backlash, is not.

Hi all,

On one of my machines i have these big ac servos. Y axis only, it has 1/16” play. I can move the axis when the drives are enabled 1/16”. This axis is 1” ballscrew with 1to1 timing belt to motor. When i removed the covers to the timing belt/pulleys, i saw when i move the axis by hand the pully on the servo is moving also. I checked and the pulley is not slipping on the motor.

So my question is, could it be a defective motor? I can turn the pully slightly by movin* the timing belt then i feel it trying to pull back which inassume is lcnc correcting the feedback. I am pretty confimdent this is where i am seeing the slight overruns in the piece i am cutting.

Could this be caused by poor tuning?

Thnaks,

Bob

Yes, poor tunning can be the reason, probably because of a low P gain.
If you inspect the following error using halscope during that move that you force you will see the error increasing if the reason is a bad tunning.

emcPT wrote: Yes, poor tunning can be the reason, probably because of a low P gain.
If you inspect the following error using halscope during that move that you force you will see the error increasing if the reason is a bad tunning.

Thanks, I upped the P in the PID and tightened up the belt and it almost disappeared completely. i will work on it more.

Thanks for the tip.

Bob