servo motor are jittering

i recently started a conversion on an old(ish) tos f2vcnc. but now i got the servo working the motors are jittering when standing still.. at the same frequntie and amplitude. almost like its overshooting its position goal. i have tried pid tuning but nothong takes the jitter away anyone nows what the problm might be? i will upload some pictures later. the drives are baumuller bus3. the picture is of when i was still building it up its all conected now.

this is how the ferror looks

fiveseven wrote:

the picture is of when i was still building it up its all conected now.

What picture?
Have a read through this, skip the wiring and testing part:
forum.linuxcnc.org/10-advanced-configura...ning-detailed-how-to

Hard to tell from the plot (higher vertical gain would help)
but it sort of looks like +- 1 count dither. If this is the case
(and that jitter is only +-1 micron or so) you could add some
deadband to the PID controller to lessen the dither.

Yeah, forgot to ask, if you put your hand on the motor, does it vibrate and how much?

yes the motors are vibrating a bit not enough to see enough to feel it. i will try to add some to the deadband and see if it fixes it.

turns out it was EMI all along. rewired it and its not all gone but its way better and good enough.