Abstract: A workpiece holding vise (10) uses a pair of jaw assemblies (12, 14) simultaneously driven in opposed reciprocation by a single shaft (26) having oppositely threaded sections to automatically center a workpiece (60) beneath a tool. Both jaw assemblies (12, 14) are suspended above the vise bed (20) by a pair of parallel guide shafts (56, 58) attached to the vise bed. Linear rolling bearings (54) fitted around the guide shafts and firmly held by opposite ends of the jaw assemblies (12, 14) provide rolling friction between the guide shafts (56, 58) and the jaw assemblies (12, 14). A bellville washer (46) at one end of the drive shaft (26) and thrust bearings at both drive shaft ends hold the shaft in compression between the vise bed (20), thereby preventing wobble of the jaw assemblies due to wear between the shaft and vise bed.

Abstract: A machine is disclosed for cleaving hard crystals (40), a typical example of which is lithium fluoride, with precision and uniformity and includes vertical axis positioning control means (12) for an adjustable spring tension guided hammer mechanism (17, 18) employed to strike an anvil (21) and thereby generate a crystal cleaving shock wave transmitted to a cleaving blade (23) having an angulated cleaving edge 24 in contact with one corner of the crystal (40). Connection between the anvil 21 and the blade is by means of a pair of vertical shafts (20) held in substantially friction free engagement by two pairs of adjustable linear bearings (19). An underlying crystal holding fixture (38) with horizontal position control means (14) includes a zero reference stop face (42) for the crystal (40) and opposing spring-loaded clamping and vertical positioning elements (43, 44) which are precisely guided.

Abstract: A crystal is sliced in a plane parallel to flat, opposed parallel end faces of the crystal. The end faces of the crystal are gripped by a pair of opposed, perforated platens of a pair of vacuum chambers, one of which is translatable relative to the other. A blade cuts the crystal through the desired plane. A spring biases one of the vacuum chambers away from the other vacuum chamber while both of the faces are gripped by the vacuum chambers and the blade is cleaving the crystal. Thereby, a sliced portion of the crystal gripped by one of the vacuum chambers is pulled away from the remainder of the crystal gripped by the second vacuum chamber when the crystal has been cleaved by the blade through the plane.