Abstract: A toolholder assembly is disclosed having an elongated spindle adapted to be rotatably driven about a longitudinal axis. The spindle also includes a longitudinally extending bore open at one end. A chuck has a collet at one end for holding a tool and an elongated shank at its other end adapted for insertion into the spindle bore. A ball lock assembly releasably coaxially secures the chuck to the spindle upon insertion of the chuck shank into the spindle bore to an operable position. The chuck also includes a conical surface at the free end of the shank. This free end of the shank engages a spring loaded piston positioned at the innermost end of the spindle bore when the chuck is inserted into the spindle to its operable position and this piston includes a conical surface complementary to the conical surface on the shank. The cooperation between the ball lock assembly and the piston coaxially and securely, but releasably, secures the chuck to the spindle.

Abstract: A tool holder is disclosed for a rotary tool having an elongated cylindrical shank. The tool holder includes an HSK body having a cylindrical bore with a predetermined inside diameter. An elongated cylindrical insert has a throughbore or collet pocket and the insert has an outer diameter larger than the inside diameter of the body cylindrical bore. Thus, the insert is insertable into the body cylindrical bore only when the body front nose is heated to a predetermined temperature at which temperature the body thermally expands to an extent that the inside diameter of the body bore is greater than the outer diameter of the insert. Upon subsequent cooling of the body, the body and insert are attached together. A collet is then used to removably and coaxially secure the tool shank to the insert within the insert throughbore. Other inserts may be used such as floating style holders, straight bore, etc.