Quote Originally Posted by RichR View Post
As soon as I send power from the vfd to the spindle the y axis stepper motor begins to turn in a jerky way.
Quick question that might help others to understand.

As written, you've not indicated that any axis was in motion when the spindle was spun-up. Are you saying that with all axis stationary, that turning the spindle on will cause the stepper on the Y-Axis to start to turn (jerkily). In one direction, or either?

Or...

Are you saying that with the axis stationary, and the spindle on, that there is no activity on the Y-Axis; however, if you then issue a G0/G1 command that the motion is jerky (when, without the spindle, it would otherwise be smooth).

(It has a bearing as to where noise/whatever can be influencing the control box).