Luthier CNC

[bluesking]

My tool tip has earth continuity, so this type of touch plate works for me.

Have you metered the resistance between collet and spindle body ?

I've metered between collet all the way to the BOB, thats what made me think it would work. I then tested the z probe (same idea as the one in your pic), thats how I know it works!

Weirdly my spindle is quoted as having ceramic bearings though so not quite sure why it does work. But I'm happy so far.