Abstract: A method is provided for effecting numerically controlled machining operations at a predetermined location. A reference feature is fixed proximate to the predetermined location and the location of a reference surface thereon is measured prior to machining to produce reference surface signals representing the coordinates of the reference surface. Location correction signals are produced in response to the reference surface signals, the location correction signals representing the difference between the measured location of the reference surface and the actual location thereof. The machining operation is performed in response to the location correction signals to effect the machining operation at the predetermined location.

Abstract: A method is disclosed for modifying coordinate data in a machining program in response to workpiece measurements made by a programmably controlled surface sensing element. The location of the workpiece and position of workpiece characteristics are determined by a series of programmed scanning cycles. The maximum, minimum and average measured positions of points on a workpiece surface are stored and may be used to calculate position offsets which may be used to modify a machining program. Further, the measured positions and offsets may be tested against programmed maximum and minimum limits to determine if the measured positions are within a tolerance band. In one embodiment, the positions of points on the workpiece surface are measured by a cutting tool operating in conjunction with a torque measuring circuit.