Patent ID: 8647176

Claim:
A method of machining a workpiece having a planar face, the method comprising the steps of: a) rotating the workpiece about a workpiece axis substantially perpendicular to the planar workpiece face; b) rotating a grinding disk centered on a disk axis about the disk axis, the disk having an annular planar disk face centered on the disk axis and lying in a plane perpendicular to the disk axis and an annular frustoconical disk face extending from an edge of the planar disk face, centered on the disk axis, and angled inward from the planar disk face; c) orienting a portion of the frustoconical annular disk face perpendicular to the workpiece axis and simultaneously pressing the portion against the planar workpiece face to premachine most of the planar workpiece face; and d) thereafter pivoting the disk and thereby orienting the planar disk face parallel to the planar workpiece face and finish machining the planar workpiece face with the planar disk face.