Expansible chuck

A chuck for gripping and positioning a cylindrical workpiece, comprising:

• a chuck body having a cylindrical surface complimentary to that of a workpiece to be gripped by said chuck and which provides a clearance with a juxtaposed face of said workpiece, said chuck body having multiple grooves extending longitudinally of said cylindrical surface and which are equally spaced circumferentially thereof;
• a radial abutment provided on said chuck body at one axial end of each of said longitudinal grooves;
• an annular member slidably supported on said chuck body for movement axially thereof;
• a radial abutment on said annular member co-extensive with said multiple grooves and positioned adjacent to the other axial end of each of said grooves;
• means for exerting an axial force on said annular member in a direction towards said other end of each of said grooves;
• and
• an elongate axially-compressible expansion member positioned within each of said grooves, each expansion member comprising an elongate transversely crenelated strip of a spring-steel like material having a radially-extending abutment portion at its respective longitudinal ends, resilient incompressible elastomeric material filling the crenelations on one side of said strip, and resilient incompressible elastomeric material partially filling the crenelations on the side of said strip opposite said one side, said radially extending abutment portions being respectively engaged by said radial abutment of the chuck body and said radial abutment of said slidable annular member, said expansion member expanding in thickness upon the application of an axially directed compressive force thereto by said slidable annular member.