Abstract: A lathe chuck includes three jaws each comprising a reciprocating jaw member to which an indexible, hexagonal, soft metal clamping member is detachably secured. Each jaw member has a raised portion which engages in a recess in the underside of the clamping member. Each jaw member also has an upright pin located at a leading edge of the jaw member, which engages in one of six slots formed in the peripheral surfaces of the recess and each aligned with a respective corner of the clamping member, thereby providing correct indexing of the clamping member.In another embodiment of the invention, two oppositely-facing leading edges are provided, so that they can be used for clamping against the inner surface of a tube or the outer surface of a bar, respectively.