Abstract: A chuck assembly having jaws to grip an annular work-piece on its outer periphery while machining other surfaces including a face and bore and an expansible element to grip the bore surface of the annular work-piece while machining the outer surfaces and a face, with mechanism for actuating the jaws and expansible element alternately, the parts supporting the jaws and expansible element comprising an assembly adapted for mounting on the headstock of a lathe to permit machining of the work-piece by tools carried on the tool holders normally present in a lathe.