How To Use Thread Plug Gages briefly describes the basics of go and no go thread gaging.
The go thread plug gage should engage the internal threaded part with very little force used. The engagement should be smooth. There is no specification regarding torque or pounds of pressure for using thread plug gages. The no go thread plug should not enter the part more than 3 turns although in practice it is advisable to limit the amount of turns to 1 ½ - 2 turns max. The user just simply counts turns.
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