Abstract: In combination, a turbine driven dental handpiece and a collet wrench therefor. The handpiece includes a rotor having a shaft, and a collet is threadedly received within the shaft. A dental bur is adapted to be inserted in one end of the collet, and the other end of the collet has a bore of non-circular cross-section. The wrench includes means for preventing rotation of the rotor shaft and means for rotating the collet relative to the shaft. The collet rotating means comprises a shaft having an end of non-circular cross-section, which end is received in the end of the collet. The wrench also includes means for rotating the shaft to advance the collet within the rotor shaft and means to prevent further rotation of the shaft after a predetermined rotational force has been applied to the collet.

Abstract: A collet wrench adapted to place a predetermined force on a collet threadedly secured in a dental handpiece. The wrench comprises a frame and means on the frame for securing the rotor shaft against rotation. A shaft is rotably mounted in the frame, and has a lower end of non-circular cross-section. The lower end is received in the collet and is adapted to rotate the collet relative to the rotor shaft. A disc having ratchet teeth is keyed to the shaft and a second disc having ratchet teeth is placed on the first mentioned disc and held there by a spring force. Rotation of the second disc causes the rotation of the first disc, and the subsequent rotation of the shaft having the end secured to the collet. After a predetermined force has been applied to the second disc, it will slip relative to the first disc, and accordingly apply a predetermined force to the collet. The pressure of the spring controls the predetermined force.