Abstract: A working pressure control mechanism for lapping, honing, and grinding machines having a rotatably mounted shaft bearing the tool within an axially translatable housing such that the shaft is carried along by the housing in the direction of the tool advance, comprising a spring capable of axially translating the housing, a signal producer capable of producing a signal corresponding to the magnitude of axial displacement caused by the workpiece and connected to the spring, and a mechanism advance control capable of receiving a signal from the signal producer, and advancing the housing to compensate for the degree of axial displacement.