Patent US 5,283,509

A tracing control system machines a workpiece to a desired contour corresponding to the surface of a model which is being traced. The tracing control system comprises a tracing control circuit, a digitizing circuit, and numerical circuits. The tracing control circuit controls a plurality of tracing axes to trace the surface of the model. The digitizing circuit is connected to the tracing control circuit through a bus, for reading the positions of the tracing axes as positional data from time to time and processing the positional data to prevent a cutter head from biting into the workpiece, thereby to generate NC data linearly approximate the surface of the model. The numerical control circuits are connected to the digitizing circuit through the bus, for positionally controlling as many machining axes as the number of the tracing axes on the NC data to machine the workpiece.