Sensor for detecting the location of a discontinuity

A sensor for detecting the location of a hole in a surface of a workpiece, comprising a sensing head having a probe adapted to engage a portion of a workpiece surface defining a hole, a boss carried by said sensing head, a housing supporting said sensing head for lateral displacement in any direction from a longitudinal Z axis of said sensor in response to engagement of a hole-defining portion by said probe, said housing being a tubular member having an interior surface and a tubular chamber at one end thereof and said boss being freely laterally displacable within the limits of said housing, a pair of displacement conversion members supported in said housing for independent axial displacement relative thereto along said Z axis and constrained against lateral movement, the displacement conversion members having end surfaces in engagement with said boss and radiused surfaces engaging said interior surfaces of the tubular member, said end surfaces being adapted to cooperate with the boss to effect axial displacement of the displacement conversion members corresponding in direction and magnitude to lateral displacement of said sensing head along X and Y lateral axes respectively and said radiused surfaces laterally retaining said displacement conversion members, and a position indicator responsive to axial displacement of each of said conversion members to generate a signal indicative thereof.