Method of generating grinding paths from a computer model for controlling a numerically controlled grinder

A method of generating a grind program for controlling a numerically controlled grinder for shaping a joint prosthesis workpiece, the grind program containing a plurality of grinding paths represented by data points generated from a computer model of a joint prosthesis, the computer model having an articulating surface, a first side, and a second side, the grinder including a grinding wheel having a wheel radius and which has a grinding surface having a nose radius, the grinder further including a fixture having a center axis for attaching the joint prosthesis workpiece, the fixture being rotatable in a radial direction about the center axis and being movable in an axial direction along the center axis, the grinding wheel being movable along a second axis that is perpendicular to the fixture center axis, the method comprising the steps of:

• (a) defining a center axis for the computer model extending from the first side to the second side of the computer model, wherein said model center axis is defined to correspond exactly with the fixture center axis;
• (b) generating a first set of data points representing grinding paths for a first ball-endmill tool having a radius equal to the nose radius, each of said data points in said first set defining the relative position of the fixture relative to said first ball-endmill tool;
• (c) determining a second set of data points from said first set of data points, said second set of data points representing grinding paths compensated radially for a second ball-endmill tool having a radius equal to the wheel radius;
• (d) storing said second set of data points in the grind program;
• (e) post-processing the grind program into a format compatible with the numerically controlled grinder;
• and
• (f) transferring the post-processed grind program to the numerically controlled grinder.