A collet chuck comprises a rotating cylinder block defining a cylindrical axis and an exterior cylindrical surface with first and second annular grooves. A collet and collet sleeve are at least partially surrounded by the rotating cylinder block. A piston slides within an annular interior space in the rotating cylinder block. A stationary port block has an interior cylindrical surface adjacent the exterior cylindrical surface of the rotating cylinder block and connects a first inlet port with a first annular groove and a second inlet port with the second annular groove. Switching pneumatic pressure between the first and second inlet ports moves the piston and collet sleeve between the clamping and unclamping positions and the gap between the rotating cylinder block and the stationary port block provides a frictionless seal.