The flat surface of this magnet is simply placed against a face plate that is perpendicular to the spindle axis. It is placed with the sphere approximately centered with the spindle axis. This device is provided with a four place wobble plate that can adjust the position of the Ultra Precise Test Sphere.

Because the holding power of the large rare earth magnet is so great, we provide a jack screw on each side of the device to break the magnetic pull so that it can be easily removed from the spindle at the end of the test. This same set of jack screws can be used to reduce the magnetic pull when first placing the magnet on the spindle. By advancing one or both of the jack screws a slight amount, the Ultra Precise Test Sphere can be more easily tapped into approximate position with a soft face hammer. Then the full power of the magnet is applied by withdrawing the jack screws, thus allowing the magnet to come into full contact with the spindle face.

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 nm) maximum and has a surface finish that is better than 0.5 micro inches (12.7 nm) 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 when using 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 its simplicity. There are no vector displacements to try and interpret, simply loosen the screw corresponding to the most positive 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.

The body of the Magnetic Authenticator™ with the four place wobble plate is machined from a single piece of 2-3 /4 inch (69.85 mm) diameter very highly permeable magnetic material. This body is electro less nickel plated for corrosion resistance.

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 have exactly the same mass.