We received the Tongtai BT-40 Spindle with the complaint of high noise along with vibrations. Also the reported runout on a 300 mm test mandrel was out of tolerance. We dismantled the spindle assembly and the same was thoroughly cleaned. Bearing condition was found to be absolutely dismal. Spindle nose taper condition was quite bad.

We ground the spindle nose within the accuracy of 1 micron. All the rotating components were dynamically balanced. Then Spindle was re-assembled. Checked the runout which was 1 micron on the spindle nose and 8 micron on a test mandrel of 300 mm length.