Abstract: An apparatus is described for forming a circumferential annular groove into a round workpiece. The workpiece may comprise two or more cylindrical members to be joined together in an overlapping relation by means of a rolled annular crimp. The apparatus or machine includes a portable main body part having an annular platform rotatable within the main body part about a centerline axis. The annular platform inner circumference defines a co-axial bore into which a workpiece may be received. A ball bearing is introduced part-way into the bore in the radial direction to contact the workpiece whereby a circumferential groove may be formed into the workpiece. The depth of the groove may be automatically controlled and the apparatus itself is circumferentially mounted about the workpiece to facilitate the application of the apparatus to the workpiece.