I have a super X3 mill from Grizzly (G0619) that I converted to cnc a little over a year ago. I also changed the pulley tooth ratio to double the spindle speed. I've noticed that above 2500rpm or so the bearings get very warm (spindle and collets are very warm after 10-15minutes of running). I'm curious if anyone knows what the rated speed is for the spindle bearings? I've seen threads for the X3 saying they are rated up to 5000rpm, but I'm not sure if the X3 and super X3 have the same bearings. I'm also wondering if anyone out there has installed new spindle bearings on a super X3. Any insight is much appreciated.

Thanks!