Milltronics VM17 Spindle Repair
This is a spindle made by Setco for a Milltronics machine. The #3 bearing of the front tri-set failed. The manufacturer or the previous rebuilder did not set the spacers correctly for the front bearing set. They had the spacers set for a much heavier preload than the speed of the spindle would allow. This caused heat and premature bearing wear that eventually lead to the failure of the spindle assembly. The taper also had 8 microns of run out.
Northland Tool kiss ground the taper and reworked the spacers to give the front tri-set of bearings the proper preload. We assembled the spindle and test ran it on our test stand at the top operational speed of 8000 rpm.