The complete body of this Authenticator™ is machined from a solid 4 inch (101.6 mm) diameter piece of high-tensile stainless steel which is heat treated to develop its maximum physical properties.

The one inch (25.4 mm) diameter Ultra Precise Test Sphere is produced from very fine grained high chrome high carbon stainless steel. It is hardened to 58 Rockwell C for wear- resistance and ultra-cold cycled for long term dimensional stability.

The Ultra Precise Test Sphere is just that, it is spherical within 2.5 micro inches (63.5 n m) maximum and has a surface finish that is better than 0.5 micro inches (12.7 n m) Ra. This is ten times more accurate than high quality bearing balls. Spheres of this quality are simply not commercially available.

Unlike tungsten carbide, this material has good uniform electrical conductivity which is so important for spindle bearing evaluation with capacitance gages.

The exact position of the Ultra Precise Test Sphere is adjusted by a four screw wobble plate. The flexure of this wobble plate is affected through an integrally-machined ligature that achieves a careful balance between flexibility and rigidity. The advantage of the four screw adjustable wobble plate over a three screw wobble plate is simplicity. There are no vector displacements to try and interpret, simply loosen the screw corresponding to the most positive displacement of the sphere and tighten the opposing screw. When approaching the final setting, the tension on the screw corresponding to the low point of the sphere is simply increased and an entirely elastic bending achieves the final movement of the sphere.

There are eight precisely-drilled holes oriented around the outer edge of the flange of this device that allow it to be securely clamped to the face of a spindle using four or more socket head cap screws.

The same eight holes allow this device to be rigidly attached to an extension shaft or magnetic adapter. In this way, one device can be used in a multitude of applications. There is a concentric counter-bore in the back of the flanged Authenticator™. This counter bore locates the shaft adapters concentric to the axis of the ultra-precise sphere.

Each Authenticator™ has an individual identification number permanently marked on its body.

An individual polar chart recording documenting the roundness of the Ultra Precise Test Sphere is supplied with each Authenticator™.

The Ultra Precise Test Sphere is attached to the body of the Authenticator™ in a manner that provides an ultra low electrical resistance between it and the body. This is extremely important when using capacitance gages for the critical evaluation of the spindle characteristics.

The Ultra Precise Test Sphere is not just glued to the body. A steel pin extends deep into a hole in the sphere and into the body to achieve an extremely strong connection. In order to preserve the dynamic balance of the device, all details are maintained very symmetrical and dimensionally balanced and constant. Each one of the four socket head cap screws used to adjust the wobble plate are carefully machined to give them exactly the same mass.

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