Method for machining multiple cuts in a workpiece to a uniform depth

Abstract

There is disclosed a method for machining multiple holes in a workpiece to a uniform depth and at a predetermined angle to the surface of the workpiece. The method is performed by a numerically controlled machine tool which orients the workpiece in space with respect to a reference coordinate system which establishes an expected position of the surface of the workpiece. The actual position of the surface of the workpiece is determined by sensing contact between the workpiece and the boring tool. Once the actual position of the workpiece surface has been sensed, the tool is advanced a predetermined distance to provide a uniform depth cut. The expected position, the actual position, and the deviation between the two are recorded to assure that the surface of the workpiece is accurately sensed during subsequent machining steps. In order to minimize false premature sensing of the workpiece, the surface of the workpiece is coated with a nonconductive enamel, air is blown across the surface of the workpiece to remove debris, and an insulating liquid coolant/lubricant is used during the drilling of the workpiece.