or by a releasable adhesive alternatively particularly where the inner ring is a very thin cylindrical sleeve such as the ring 14a in the embodiment of fig3 the mandrel 50 may be formed of etchable material such as aluminum on which the ring blank b is formed directly on the mandrel by electrodeposition or similar processes upon being supported on the working end 52 of the mandrel 50 the blank b is machined by honing or other such abrading processes to form the peripheral groove 42c by rotation of the mandrel 50 and application of a honing tool not shown also during this machining process particularly in the case of the ring 14c of the embodiment of fig4 sharp corners such as those at the junction of end 40c and the outer cylindrical surface 34c fig7 of the ring 14c as well as the corner between the groove 42c and the upper portion of the outer cylindrical surface 34c would be rounded or at least softened to eliminate cutting edges once the ring 14c is machined on the mandrel 50 the outer ring 12c is positioned on the anvil 56 as shown in fig7 and the assembly of the mandrel and the formed inner ring 14c forced downwardly into the outer ring 12c to the position represented by phantom lines in fig7 the chamfer 32c on the outer ring 32 will facilitate the press fit of.