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4.11 Thread Plug Gages

D.M. Donner

A drawer with an assortment of thread gages.
Figure 4.116. Drawer of thread gages in a metrology lab / Image Credit: Damon Donner, CC BY 4.0

Thread plug gages are used to measure ID threads. Machine shops have a large inventory of thread gages due to the volume of threads available and the required class of fit.

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Figure 4.117. A close-up view of a ½-13 UNC 2B thread gage with an end marked “GO” and the other marked “NOGO”. / Image Credit: Damon Donner, CC BY 4.0

Thread gages come in the go/no-go configuration with the no-go plug using a pitch diameter larger than the class of fit allows, and the go size set to the minimum thread pitch diameter for the class of fit. The thread gage above is for a ½ X 13 UNC 2B thread with a pitch diameter of .4500 for the go end, and a .4565″ pitch diameter for the no-go end.

Attributions

  1. Figure 4.116: Drawer of thread gages in a metrology lab by Damon Donner, for WA Open ProfTech, © SBCTC, CC BY 4.0
  2. Figure 4.117: ½-13 UNC 2B thread gage by Damon Donner, for WA Open ProfTech, © SBCTC, CC BY 4.0

License

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Introduction to Machining Copyright © by SBCTC is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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