I tend to check my German made dial caliper regularly against micrometers and never saw it off more than +/-.001. But was measuring a 1.125" OD on a needle bearing assembly and kept getting .003" small. Compared with a vernier caliper, and 2 micrometers, and darned if the dial caliper was not off by around .0025". But, if it was used for measuring items that were 1.065" or .984" piston pins, the dial caliper was spot on.
Observing the dial movement going very slowly, I spotted some small movement of the needle center as it moved past one point on the dial; happened each revolution at that particular spot, and that was the area in which the above measurement was off. I am guessing that the gear on the back of the needle is damaged or worn a bit right at one or 2 particular teeth or the internal bearing is shot.
So, keep a good check on anything like a dial caliper for engine work. This one will be fine at the reloading bench but won't get used much for engine work anymore.
