Abstract: A printed circuit board having a substrate on which circuitry is formed, is spot-faced, by cutting at first the circuitry, and then by spot-facing the substrate up to a desired depth.

Abstract: A spot facing method and apparatus for processing a printed circuit board incorporates a sensing device having a sensor probe capable of sensing the level of the surface of a printed circuit board, another sensing device for sensing the position of the end of a tool, measuring circuits for measuring the distance between the sensing probe and the end of the tool and the distance between the surface of the printed circuit board and the end of the tool in accordance with the signals from the sensing devices, and a controller connected to the measuring circuits so as to control the feed of the tool thereby attaining a high dimensional precision in the depthwise direction in the spot facing.

Abstract: A method of machining the contour of a printed circuit board by effecting a relative feed movement between a rotating tool and the other periphery of the printed circuit board. The electrical current value of a drive motor for driving a spindle to which the tool is attached is detected and an operation is conducted for changing the machining condition in such a manner as to reduce the electrical current value of the spindle drive motor and, at the same time, for changing also tool diameter compensation amount to a value corresponding to the machining condition after the change, at every time the detected electrical current value has reached a predetermined current value immediately before tool breakage and repeatedly by a predetermined number of times.

Abstract: A work holding device used in an external form cutting machine for printed boards, the cutting machine including a work mounting table movable in X direction and a cutter mounting spindle movable in Y direction perpendicular to X direction, comprising holding device disposed above the table, pushing device for pushing said holding device, elevating device for raising and lowering said holding device. The holding device and the elevating device engage with each other slidably in a vertical direction with the pushing device interposed therebetween. By virtue of these arrangements, the printed boards are surely holded, resulting in an uniform cutting surface of piled printed boards. Holding pins used in prior arts for holding printed boards are not required, resulting in an improved operational efficiency of the cutting machine.