Abstract: A work holder assembly for use in clamping a workpiece being machined. A chuck includes a fixed sleeve about which is mounted a rotatable collet. A plurality of individual clamps extend from circumferential spaced locations associated with the collet. The clamps each include a first spring biased and linear traveling component actuating a second radially traveling and adjustable component into engagement with annular disposed locations of the workpiece. Each the clamps exhibits a wedge shape at an interface between the linear and radial components, both in order to minimize clamping forces and to prevent backdriving of the clamps by the tooling. A fluid pressure extends through a location in the chuck, the collet further having a fluid delivery component in communication with the fluid supply and which is in contact with workpiece engaging locations, to overcome the spring bias of said pin in a fluid actuated release condition.