Northfield Precision Instrument Corp. introduces its new Model 620 chuck. This 6"-dia. 3-jaw chuck has a 1"-dia. counterbore (hidden), with special sub-jaws, inserts and side loading base stop and stop pad. Due to the part geometry, it had to be side loaded between the jaws and needed to rest on the small boss at the end of the slot. Two weights were added to balance the chuck. Changeable insert stop pads repeat to 0.0001" TIR when removed and reinstalled.