The model DPH-400W from Northfield Precision Instrument Corporation is a four inch diameter diaphragm chuck with special jaws and stops. The stops have three "air detect" holes for part seating conformation, which air is pumped through, and when the part rests on the stop, the air pressure rises, tripping a pressure switch telling the machine to start machining. Four clover adapters have grooves for a CAM follower to snap into for orienting the chuck when stopped. These are mounted to a four spindle Theilenhaus machine.