Acer Surface Grinding Spindle Failure
Acer surface grinding spindle, 3600 RPM, lifetime grease bearing lubrication, coupling drive
One of our New England customers was experiencing very poor part finish on their Acer surface grinder. When we picked up the spindle and its direct-drive motor one cause was immediately apparent. At some point, the rubber “spider” insert of the Lovejoy-style coupling had worn out. As the spindle continued to be operated, the spindle and motor halves of the coupling became heavily worn, as did the spindle-side drive key. Our inspection also showed that the bearing grease in both the spindle and motor was old & degraded, the wheel hub taper had excessive runout of >8µ and the taper threads had some superficial damage.
We performed a kiss grind on the hub taper to improve the runout and reworked the taper threads. We replaced the bearings & assembly screws in the spindle and motor, and installed a new drive key and motor coupling. When final assembly was complete, we ran the spindle to break in the new bearing grease while checking the vibration & heat signature and balanced the spindle. Now our customer has a surface grinder which produces a consistently fine finish like it did when it was brand new.