That's
always bothered me a bit. I've replaced the 2-wire cord in a
drill with a 3-wire one, attaching the ground wire to the field coil
laminations. While not perfect, it's probably better than nothing.
Remember old (pre ~1970) power drills? : non-polarised plug,
ungrounded, and *aluminum* housing and handle.
No, I rememebr pre-1970 poer tools. Aluminium casing, 3 core cable,
proper ground to a polarised mains plug.
-tony