An apparatus for positioning a workpiece comprises a plurality of pedestals each comprising a first portion having a first width, a second portion having a second width greater than the first width, and a chamfered portion interposed between the first and second portions. The inventive apparatus further comprises a support having a plurality of holes therein for receiving the plurality of pedestals, the support further having a plurality of chamfered portions with one the chamfered portion about a periphery of each the hole. A base urges the chamfered portions of the pedestal away from the chamfered portions of the support.