Checking Perpendicularity Between Face and Centerline of a Shaft
The face to be checked is the pink shaft bottom.
Turn the shaft several revolutions while keeping a continuous contact between the shaft and the brown pin (for example by setting the base inclined). Get max and min values (E1 and E2) shown by the indicator.
Non-perpendicularity P = (E1-E2)/2A
A: center distance of indicator and the brown pin.