Abstract: A collet head for securing to a collet body for machine tools has a plurality of spaced segments arranged in a circular configuration having spaced slots between each segment. Each segment has a front face, a rear face, an inside work gripping surface, an outer cam surface and left and right side faces. Each segment also has an extraction hole in the front face thereof for receiving extraction tool fingers. On the left and right side faces of each segment is a lock recess extending from the front face of the segment and extending rearwardly towards the rear face. The lock recess comprises an enlarged portion and a narrow portion. The narrow portion of the lock recess opens into the respective side face of the segment. Each of the lock recesses cooperates with the lock recess on the adjacent side face of the adjacent segment.