Which group of thread sizes is listed as NC thread sizes?

Which group of thread sizes is listed as NC thread sizes?

• A. 12-24, 1/2-13, 10-24
• B. 14-20, 1-80, 3-16
• C. 6-32, 1/4-20, 5-40
• D. 4-40, 3/16-24, 1/8-22

Answer: (A)

National Coarse threads use the coarser pitch family, meaning fewer threads per inch for a given diameter. The group given includes three sizes that all have coarse pitches: 12-24, 1/2-13, and 10-24. Each of these is a coarse-thread combination for its diameter, typical of NC (often aligned with UNC in modern terminology). The other groups mix sizes that include finer pitches (for example, 6-32, 5-40, 4-40, 3/16-24, 1/8-22, and even 1-80), which are not all coarse. So the trio that stays within the coarse-thread family best represents NC thread sizes.

National Coarse threads use the coarser pitch family, meaning fewer threads per inch for a given diameter. The group given includes three sizes that all have coarse pitches: 12-24, 1/2-13, and 10-24. Each of these is a coarse-thread combination for its diameter, typical of NC (often aligned with UNC in modern terminology). The other groups mix sizes that include finer pitches (for example, 6-32, 5-40, 4-40, 3/16-24, 1/8-22, and even 1-80), which are not all coarse. So the trio that stays within the coarse-thread family best represents NC thread sizes.