Quote Originally Posted by Toolmaker51 View Post
Don't know the exact term, but there is an issue where stray current erodes contact areas of bearing components and races. IIRC, VFD rated motors have additional frame grounding to bypass the bearings.
Do they rely on the spindles discharging static through the workpiece? So for example the bearings in a mill used to machine aluminum will last longer than a similar mill used to machine UHMW?

My router table produces an ungodly amount of static when running. It's basically a Van de Graaff generator. The spindle is 3 phase VFD driven. I'm now questioning whether I should try grounding it or not. I really want to take that spindle apart. Perhaps it could use some conductive grease and a ground strap.