Workpiece positioning vise

A workpiece positioning device comprising:

• a plurality of spaced apart elongate structural members (22, 24);
• a pair of plates (16, 18) interconnecting the ends of said structural members to form a rigid bed (20);
• a drive shaft (26) having end sections (27) of lesser diameter rotatably supported by said end plates, said end sections forming junctions (44) with a pair of oppositely threaded intermediate sections (30, 32) of greater diameter lying between said end plates;
• a pair of thrust washers (42) fitted between said end sections and said end plates;
• a pair of facing jaws (12, 14) each having split arms (50) on opposite ends defining coaxial lumina, and protruding tongues (37, 39) engaging said oppositely threaded intermediate sections;
• a plurality of adjustable diameter linear motiong bearings (54) clasped in said lumina by said split arms;
• means (60) for adjusting the diameters of said lumina;
• at least a pair of parallel cylindrical guide shafts (56, 58) passing through said bearings supported by said end plates with sufficient separation from said structural members to prevent said jaws from touching said structural shapes;
• and
• a bellville washer (46) having an aperture of intermediate diameter positioned around one of said end sections in compression between one of said junctions and end plates.