10/23/2026
A DOP reading that repeats to within a tenth can still be wrong by two thousandths.
Repeatability feels like proof. It isn't. A pin seated in the root fillet instead of on the involute flank will sit there the same way every time, and your mic will agree with itself all afternoon.
Pin size, pin class, odd tooth counts, heat off the grinder, burrs. New post covers the setup errors behind most disputed readings, and when a dedicated gage is worth it (and when it isn't).
https://veittool.com/ball-pin-dob-dop-gages-explained-getting-diameter-over-pins-right-the-first-time/