Rod and apparatus for calibrating magnetic roll testing apparatus

A calibration rod (1) with grooved track (2) and a testing apparatus (17) for magnetic rolls that produces an accurate homing location and probe-to-probe reference for repeated test verification at many testing locations. The grooved track calibration rod can be transported to different equipment to verify that equipment is performing similarly, has improved accuracy, has temperature compensation, uses a circumferential drive movement from one end of a roll magnet and verifies angular position from the other end, eliminates the possibility of angular inaccuracy from twisting of the part being measured during clamping and provides for improved accuracy of several degrees. A high order polynomial curve fit of the data is used to determine the true value of the Gauss level being measured during 360 degree revolution. The apparatus takes measurements to accurately measure magnetic differences which define differences in probe operation. The value of other probes will be matched (multiplied by a percentage) to a first master reference probe. The apparatus eliminates twist, which can affect pole location accuracy by several degrees.