Established in 1952

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The Shaft-Mounted Authenticator™ AUT-1000

An Authenticator™ is a device used to evaluate the axis of rotation of a precision spindle. It is basically a coupling device. It holds an Ultra- Precise Test Sphere and temporarily, but rigidly attaches it to the spindle being evaluated. This basic version of the Authenticator™ (Part Number AUT- 3000) has an integral drive shaft for mounting it in the machine spindle.

The standard configuration of this device is supplied with a one and one quarter +.0000 -.0005 inch (31.75 +.00000 -.01270 mm) diameter shaft. Custom-manufactured drive devices will be made to satisfy your specific needs. Drive shafts of any English or Metric diameter and other special configurations such as tapers, including internal threads for draw bar, may be quickly produced at reasonable cost.

Facilities are included for precisely aligning the axis of the sphere with the axis of rotation of the bearing system.

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 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.

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 (12.7nm) 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 the good uniform electrical conductivity that is so important for spindle bearing evaluation with CAP gages.

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 evaluating the spindle characteristics.

The Ultra-Precise 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.

The entire body of this Authenticator™ is machined from a solid piece of 3 inch (76.2 mm) diameter high-tensile stainless steel which is heat treated to develop its maximum physical properties.

In order to maintain the dynamic balance of the device, no clamping flats are machined on the drive shaft. Custom-machined flat or flats will be provided to meet customer specifications. All diameters are held concentric. All details are very symmetrical and dimensionally constant yielding an excellent dynamic balance. 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.

Authenticators