A 3/4"-10 NC tap requires a larger tap drill than a 3/4"-16 NF tap.

A 3/4"-10 NC tap requires a larger tap drill than a 3/4"-16 NF tap.

• A. True
• B. False
• C. Not sure
• D. Not applicable

Answer: (B)

The key idea is how tap drill size relates to thread pitch and depth. For a given major diameter, a coarse thread (fewer threads per inch) has a deeper thread profile, while a fine thread (more TPI) has a shallower profile. When you drill the pilot hole before tapping, a deeper thread means less material around the hole after tapping, so the starting hole is smaller. A shallower (finer) thread means you start with a larger hole. So for a 3/4"-10 NC (coarse) versus a 3/4"-16 NF (fine) tap, the coarse thread would use a smaller drill, and the fine thread would use a larger drill. The statement that the 3/4"-10 NC tap requires a larger tap drill is not correct.

The key idea is how tap drill size relates to thread pitch and depth. For a given major diameter, a coarse thread (fewer threads per inch) has a deeper thread profile, while a fine thread (more TPI) has a shallower profile. When you drill the pilot hole before tapping, a deeper thread means less material around the hole after tapping, so the starting hole is smaller. A shallower (finer) thread means you start with a larger hole.

So for a 3/4"-10 NC (coarse) versus a 3/4"-16 NF (fine) tap, the coarse thread would use a smaller drill, and the fine thread would use a larger drill. The statement that the 3/4"-10 NC tap requires a larger tap drill is not correct.