Present-day examples of such threads would include the Unified, the Whitworth and the Acme forms. One of the early forms was the Sharp V which is now used only occasionally. Symmetrical threads are ...

specific thread designation (UNS, UNF, UNC, NPT, ACME, Buttress), part tolerances and gaging frequency (shop vs. high volume production). Thread gages can be one of any number of types of gages. These ...