Numerically controlled measuring device

A numerically controlled coordinate measuring machine, comprising, part-support means for supporting a part to be measured, a probe, a plate supporting said probe, a head supporting said plate, means supporting said head and said part-support means for relative movement along three coordinate axes, drive means for providing relative movement between the part-support means and the head, said probe having an idler roller for contacting a part being measured, said probe being rotatable about a roller axis which is aligned with one of the coordinate axes, said probe being supported for movement relative to said plate in two mutually perpendicular directions which are perpendicular to the roller axis and correspond to two of said coordinate axes, elastic return means supported on the plate for biasing the roller axis toward a given position relative to the plate, two measuring pick-ups for sensing the distance measured along said two directions between the roller axis and said given position, electronic calculator means for receiving signals from the measuring pick-ups and the coordinates which indicate the location of the head relative to the part-support means and for calculating coordinate locations of points of contact between the roller and the part being measured, said plate being biased against said head by an axial spring and supported on the head by three balls positioned in three radial grooves, means for detecting any separatory movement between the plate and the head to stop the machine when said separatory movement occurs.