Parsons recommended a method of automatic machine control that would guide a milling cutter to produce a "thru-axis curve" in order to generate smooth profiles on work pieces.

This paper analyses the geometrical character of curve of edge of form milling cutter, and infers the mathematical equations of curve, The center coordinates of conical button-shaped are evaluated.

The cutter curve is fitted with the least square method and corrected to assure the corrected generation surface is identical with that of original fitted curve.