Abstract: A surface finish measuring device for gear teeth. The device includes a probe for tracing an involute surface such of a gear tooth, a computer numerical control (CNC) machine for receiving perimeters relating to the geometry of the structure being measured and rotating the structure at a preferably constant angular velocity; and a computer for determining which measured points on the involute surface are to be used by a display device such as a strip chart recorder to graphically illustrate, in a highly magnified fashion, the topography of the involute surface being measured. The present invention overcomes the problems associated with the rate at which the distance between consecutive measurements changes when measuring an involute surface to provide a collection of relatively evenly spaced measurement points.

Abstract: An expanding arbor apparatus for establishing the radial positioning of a workpiece of the type having a profiled internal surface. The arbor has a plurality of probe members which expand or contract when the separation between a pair of conical surfaces acting on the probe change. The radially outer end of the probes can be provided with any desired contour or shape to engage the workpiece surface in any desired manner. The arbor may be used with numerous workpiece internal profiles such as internal gear teeth or splines.