The Cantilever Ball Bar

The master spheres are manufactured from high chrome, high carbon stainless steel that has ultra fine grain structure. The master spheres are hardened to 58 Rc and thermo cycled for long term dimensional stability. The 3/4 inch (1.9cm) diameter tubular steel construction provides a very rigid light weight structure. The Ultra Precise Stainless Steel spheres are attached to the ends of the Ball Bar (Dumbbell) by gluing. A steel pin is inserted into a drilled hole in the master sphere and in the bar as the high strength glue is applied during assembly. The result is an exceptionally strong, shock resistant, bond between the master sphere and the bar.

The two support spheres are held in two magnetically pre-loaded kinematic couplings attached to a very rigid tee shaped aluminum rail of the Way Out Ball Bar (Dumbbell) Support ( see Technical Data Sheet C.M.M.-16, Page 2.). The first kinematic coupling consists of three precision spheres arranged in a circle to form a three contact cup. The second kinematic coupling consists of two precision cylinders that form a dual contact cradle. Each of these kinematic couplings has a powerful rare earth magnet implanted just below the surface in the center of the coupling.

This design constrains five of the six degrees of Ball Bar freedom without introducing any over constraint.

The Cantilever design provides three outstanding advantages over the conventional free standing Ball Bar.

The most important advantage is the very rigid support it provides. This design virtually eliminates any of the deflections caused by the contact force of the measuring probe.

The second advantage is that the master spheres are never contacted by the kinematic couplings which might cause scratching, wear or brinelling.

The third advantage is that the entire surfaces of the master spheres are exposed for evaluation by the C.M.M. measuring probe.

The Cantilever Ball Bar is usually used with The Way Out Rail, see page: CMM-16, Page 2.