Abstract: The chucking ring of this invention finds its principal utility in the clamping of top jaws used in a machine tool, such as a lathe, having a chuck and equipped to machine successive workpieces. The chucking ring includes a flanged head on one end of a tubular body portion that removably receives a plug and an adjustable stop for workpieces. The chucking ring is fastened to the chuck with bolts in its inactive position where it functions as a replacement for a chip bushing. The bolts may be removed and the chucking ring rotated to its active position with the flanges on the head aligned with the master jaws for chucking by the master jaws. The top jaws are bolted to the master jaws for machining.