When parts are inspected it is necessary to maintain an ambient temperature in the room and of the parts so the highly sensitive tolerances are accurate to within .002 microns or .00008 inches. Shafts are inspected for correct O.D. sizes, run out, and straightness.
Bearing housing I.D. sizes are inspected for correct tolerances, and concentricity. Shaft O.D. and I.D pilots, tapers and faces are also inspected as well as the shoulders where the bearings will sit. It is even necessary to check the O.D. where the pulley or encoder may sit.