Abstract: A tubular chuck collar with a plurality of teeth circumferentially arranged around the base thereof to form a toothed track is fitted over the inner cylinder of a conventional chuck assembly in spaced relationship to the outer cylinder of the chuck assembly such that the toothed track of the chuck collar opposes the conventional toothed track on the outer cylinder. A securing means releasably secures the collar to the inner cylinder. The toothed track of the chuck collar includes at least one section oriented at an incline relative to the toothed track on the outer cylinder, whereby a bladed instrument such as a screwdriver may be inserted into the gap between the collar and the outer cylinder to simultaneously engage the teeth in both toothed tracks. The screwdriver so inserted is twisted about its longitudinal axis to simultaneously apply opposing torques to the collar and the outer cylinder.