Abstract: A cutting tool which includes a mounting shaft and a chip breaker positioned on the mounting shaft. A cutting plate is supported between the mounting shaft and the chip breaker, with a clamping jaw being positioned on the chip breaker. A clamping screw is releasably held in the cutting tool mounting shaft for holding the clamping jaw and the chip breaker against the tool mounting shaft. The clamping screw has a longitudinal axis and an outer portion which is situated externally of the clamping jaw. A spring is provided for urging the chip breaker against the clamping jaw. The clamping jaw and the chip breaker have interengaging teeth on their surfaces which are oriented towards one another. The chip breaker further includes a throughgoing aperture through which the clamping screw passes. The throughgoing aperture is enlarged to form an elongated opening for permitting lateral movement of the chip breaker transversely to the longitudinal axis of the clamping screw.