Juddering Y axis

[JAZZCNC]

If there's nothing obviously mechanical causing this judder then it could possibly be resonance causing the motors to judder. This is a typical mind band resonance problem. Called mind band because it affects motors at mid to high rev ranges or frequency.

To quickly see if this could be the cause then try changing the micro stepping on the drives and see if it changes or moves the point when it happens.
If it's midband res then changing the MS can often eliminate the judder altogether, doesn't fix the problem just changes the frequency to a point it doesn't affect motors.