LATHE OPERATIONS - OD1645 - LESSON 1/TASK 3
The pitches, basic dimensions, and tolerances for sizes of 1/4 inch and
larger are basically the same for the Unified and American (National) thread
forms. The coarse thread series of the Unified system is designated UNC and
the fine thread series UNF.
FIGURE 40. UNIFIED AND AMERICAN
(NATIONAL) STANDARD SCREW THREADS.