Also, the time to inspect and gage wear is reduced. In addition, time consuming calibration is reduced. The next objective is to position the actual size of the screw thread within the Pitch diameter tolerance limits. The correct positioning of size should allow for maximum use of the Functional size tolerance that remains. M standard as the how to do document.
M defines how to measure threads for dimensional acceptability.
It also defines the gage geometry for Maximum and Minimum material limits of size measurements. These Functional gages provide some control at the minimum material limit when there is little variation in thread form characteristics such as lead, flank angle, taper and roundness. These are called attribute gages and provide no size information within Pitch diameter tolerance limits. These Functional gages alone provide only a check for assembly. Other thread characteristics such as lead, flank angle, taper and roundness variations are confined within these limits with no specific control of their magnitudes.