Rotating ball nut assembly for fast linear cnc motion

[Saltfever]

I understand your concerns about inertial effects on a long shaft and revolving the nut to compensate is a good idea. Thanks for sharing your results. I see the Y axis assembly has a lot of aluminum in it and, of course, a heavy spindle. So I am assuming the mass of the Y assembly is probably equal to or greater than the mass of the X ball screw. Even though the Y axis has a different CG location and structural shape, acceleration of similar (or greater) mass has issues as well. Are we primarily concerned with the LONG spinning X shaft and not the shorter Y assembly? Is there anything to be gained by revolving the Y nut?