Abstract: Attachments for self-locking or conventional key-operated chucks on hand drills make possible simplified operation thereof. An externally threaded ring carried by the drill surrounding the chuck is internally beveled at its outer end and mates with a threaded nut. A split ring with wedge-shaped cross section is positioned between the nut and the beveled end of the ring so as to clamp the chuck to the ring when the nut is tightened. A cap made of an elastomer attached over the nose of the chuck has in its end a slot or crossed slots which grip a drill bit when it is thrust therethrough.

Abstract: The chuck comprises a cylindrical body portion attached to the drill motor shaft and formed with inwardly and downwardly inclined slots which holds its jaws. Those jaws carry circumferential threads on their outer surfaces. An internally threaded ring rotatable about the chuck body meshes with the teeth on the jaws and causes them to move downwardly or upwardly as the ring is rotated. The ring is provided with an external groove which is not quite fully circumferential. The chuck body and ring are enclosed by a rotatable sleeve having an internal recess in the plane of the groove only large enough to hold a ball bearing between it and the groove on the ring. The chuck body and sleeve are provided with interlocking means which prevent longitudinal displacement but permit rotational movement therebetween. The chuck is caused to grasp the drill stem by holding the sleeve in hand and starting the drill motor.