Tolerance rings from USA Tolerance Rings, Pennington, (www.usatolerancerings.com), let a maker of exercise eliminate a costly secondary machining operation on assemblies.

The tolerance rings go between eight ball bearings and bores in Cybex Arc cross trainers from Cybex International, Medway, Mass. The rings compensate for out-of-round and minor misalignment caused by the welding operation.

Tolerance rings are made from a thin, spring-steel strip into which waves, corrugations, or bumps are formed. The features elastically deform to exert a holding force between components yet allow for ease of assembly. Holding force scales with wave count and the coefficient of friction against mating components.