Abstract: A toolholder 1 of the type including a collet 5 integrally formed with a shank 3 is provided with an interface between a locknut 7 and collet 13 which substantially reduces the torque required to turn the locknut 7 into a position which radially collapses the collet segments 17. In this interface, one of either the inner locknut surface 23 or the outer surfaces of the collet segments 17 includes an engaging portion 56 for wedgingly flexing the collet segments 17 inwardly when the locknut is turned, and a non-engaging portion 58 disposed between the engaging portion 56 and the shank mounted ends of the collet segments 17. The non-engaging portion 58 reduces the torque required to turn the locknut 7 by reducing the binding forces that would otherwise occur between the ends of the collet segments 17 and the inner locknut surface 23.

Abstract: An apparatus and method for balancing a high speed rotary tool assembly (1) is provided, wherein the apparatus includes a rotary tool holder (3) having an axis of rotation (11), a cutting tool retainer (13) in the rotary tool holder (3) having a lockring (23) that circumscribes the axis of rotation (11) of the holder (3), and a pair of axially spaced balancing rings (35a, 35b) for balancing the entire rotary tool assembly (1) which are rotatably mounted around bearing surfaces (37) circumscribing the lockring (23) so as to be angularly positionable around the axis of rotation (11) of the tool holder (3). In the method of the invention, the unbalance of the tool holder (3) and cutting tool (17) is first determined, and then the rings (35a, 35b) are rotatably adjusted about the bearing surface (11) on the lockring (23) to create an unbalance which cancels out the determined unbalance of the tool holder (3) and cutting tool.

Abstract: The present invention is a tool holder for receiving an endmill or similar tool. The tool holder includes a shank portion adapted to fit into the spindle of a machine, and a closed end collet integrally formed with the shank portion. The collet includes an axial bore for receiving the tool and a plurality of resilient collet segments for gripping the tool. The collet segments are separated by a plurality of axially extending slots which terminate inwardly from the forward end of a collet. A continuous tie ring extends around the forward end of a collet and joins the plurality of collet segments together. The continuous tie ring provides for increased radial stiffness at the forward end of the collet which improves accuracy and repeatability of tool location. A lock nut threads onto the collet to collapse the collet segments radially inwardly to grip the tool.