Edge, runout, and true center of rotation finder

Abstract

A device for finding the runout of a machine spindle. The device includes a ball bearing mounted to the end of a short, precision shaft. The ball bearing includes a pattern of dots or similar markings on an upper face of an outer ring of the bearing. The device is mounted into a chuck attached to a spindle and is lowered to the level of an edge of a workpiece. A workpiece edge is moved toward the bearing of the device. A machinist zero's out a digital position readout of the machine's lead screw dial when the workpiece first contacts the bearing. The machinist determines the amount of runout of the spindle by observing the motion of the pattern on the bearing as the workpiece moves from first contact with the bearing to a point when the bearing stops moving.

Dependencies are inferred from the claim text.