Abstract: The tool spindle has a drive plate on which a cutter is mounted. Drive keys on the drive plate engage slots in the cutter so that the cutter rotates with the drive plate. A clamp bar is provided to clamp the cutter against the drive plate. The cutter is formed with clearances which register with the clamp bar when the cutter is rotated relative to the clamp bar, so that the cutter may be removed from the drive plate. A new cutter is then reverse rotated into a position in which it may be clamped by the clamp bar. A spring holds the clamp bar in its clamping position. The quick change system also includes two or more locking fingers which are activated by centrifugal force to maintain the cutter clamped to the drive plate even in the event of failure of the spring which normally holds the clamp bar in its clamping position.