Automatic apparatus for measuring internal diameters including calibrating means

An automatic inner diameter measuring apparatus having: an inner diameter measuring gauge head (70) having at least one contacting element capable of being inserted into bores of an object (W) to be measured and being movable a radial direction of the bore; a stocker (40) capable of holding a plurality of inner diameter measuring gauge heads (70) corresponding to different diameters; means for 3 dimensional movement of any inner diameter measuring gauge head object (W) to be measured; a plurality of master ring gauges capable of adjusting the inner diameter measuring gauge heads (70) to zero thereof and a ring gauge support capable of holding the master ring gauges. The apparatus allows measurement of objects moving on a continuous production line.