2-Threads, Taps, and Tapping - Thread Tolerances
|Just like for machining operations, internal and external threads must be machined within a specific tolerance zone.
There are three tolerance classes of fit:
1=lose, 2= medium, and 3 = tight.
The most commonly used in general manufacturing is the class 2 tolerance. However in the defense and aerospace industries the class 3 is more widely used.