Calibration of ring gauges

Either a ring gauge or setting ring is callipered in a ring gauge calibrator. Two versions of ring gauge calibrators are available, the mechanical comparator type where the ring gauge under calibration is compared with a block of gauge blocks and the comparator of more recent origin where the comparison is against a laser holoscale or gratin interferometer.
Alarge amountr of diameters of the ring gauge are measured and the mean computed. Also the out of roundness or ovality of the ring gauge is estimated.