A flexible coupling for attaching a collet to a draw bar includes a draw bar having a first longitudinal axis and a first coupling portion. The first coupling portion includes two or more legs spaced apart from one another with each of the legs having first coupling surface formed thereon. The flexible coupling includes a collet having a second longitudinal axis and a clamping portion proximate one end of the collet. The collet includes a second coupling portion proximate a second end of the collet. The second coupling portion has a second coupling surface formed thereon and configured in a shape complementary to the first coupling surface so that the first coupling surfaces moveably engage the second coupling surface such that the first longitudinal axis and the second longitudinal axis are coaxial when an axial force is applied to the draw bar and the collet.

A collet extends from a first to second end. A hoop section proximate the first end and has a continuous cylindrical interior surface that extends to an intermediate location between the first and second end. First and second legs each extend from the intermediate location. The first and second legs are spaced apart from each other. A holding section is located proximate the second end which has by a flange that extends radially inward from an exterior surface of the and terminates at a clamping surface.

A flexible coupling for attaching a collet to a draw bar includes a draw bar having a first longitudinal axis and a first coupling portion. The first coupling portion includes two or more legs spaced apart from one another with each of the legs having first coupling surface formed thereon. The flexible coupling includes a collet having a second longitudinal axis and a clamping portion proximate one end of the collet. The collet includes a second coupling portion proximate a second end of the collet. The second coupling portion has a second coupling surface formed thereon and configured in a shape complementary to the first coupling surface so that the first coupling surfaces moveably engage the second coupling surface such that the first longitudinal axis and the second longitudinal axis are coaxial when an axial force is applied to the draw bar and the collet.

A chuck with automatic positioning collet is provided. The chuck includes a rotation member, over which a stationary member is sleeved. A piston is arranged inside the rotation member by means of a slidable sleeve that includes an internal thread screwed to an external thread of a collet. The rotation member includes an elastic piston pin assembly selectively alignable with a positioning groove of the collet. The stationary member is provided with two gas passages through which gas introduced may drive the piston to move in opposite directions so as to move the slidable sleeve and the collet in opposite directions to cause a tapering hole of the rotation member to loop tightly up or release the collet and an object received in the collet and the gas simultaneously drives the elastic piston pin assembly to position the positioning groove of the collet.

A chuck with automatic positioning collet is provided. The chuck includes a rotation member, over which a stationary member is sleeved. A piston is arranged inside the rotation member by means of a slidable sleeve that includes an internal thread screwed to an external thread of a collet. The rotation member includes an elastic piston pin assembly selectively alignable with a positioning groove of the collet. The stationary member is provided with two gas passages through which gas introduced may drive the piston to move in opposite directions so as to move the slidable sleeve and the collet in opposite directions to cause a tapering hole of the rotation member to loop tightly up or release the collet and an object received in the collet and the gas simultaneously drives the elastic piston pin assembly to position the positioning groove of the collet.

A cutter fastening apparatus has a body, a collet, a cutter, and a cap. The body has an outer thread. The collet is mounted in the body and has an abutting groove formed in an outer surface of the collet and a through hole formed through a front surface of the collet. The cutter is mounted through and fixed to the through hole of the collet. The cap is screwed with the outer thread of the body and has a driving ring portion protruding from an inner surface of the cap and a balance groove formed in the inner surface of the cap and being adjacent to the driving ring portion. The cap has a clamping portion protruding from the inner surface of the cap and a holding portion protruding from the inner surface of the cap.

A chucking device for a tool includes a tool receiving element; a collet for clamping the tool, the collet being inserted in an opening in the tool receiving element; a clamping nut for axially displacing the collet in relation to the tool receiving element; and a pressure piece which is arranged between the clamping nut and the collet and is rotatably mounted in relation to the clamping nut, by means of which piece the collet can be axially displaced in relation to the tool receiving element by the clamping nut. To permit a tool shank to be securely clamped in and released from the collet, even under extremely high clamping forces, the pressure piece has coupling elements for a torsion-proof connection to corresponding mating elements of the tool receiving element.