When I worked for the big corporation, we often used magnetic proximity
switches for this sort of thing. You've just got to find a place where you
can drill a 1/4" hole and imbed a magnet. The switch itself closes when
the magnet is within a 1/4 inch - non contact and good for 100,000s of
cycles.

My "prox switch" guru was out today... But I know we use both NPN/PNP type
sensors regularly so this may be an option if they can be put in series with
the dry contact "proof of return" switch on the drill itself.
--


Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com

V8013-R