National Course Thread (N.C) vs National Fine Thread (N.F) differ in which general characteristic?

• A. National Course Thread has coarser pitch than National Fine Thread.
• B. National Fine Thread has coarser pitch than National Course Thread.
• C. They have the same pitch.
• D. One is metric while the other is imperial.

Answer: (A)

The main idea here is thread pitch—the distance from one thread crest to the next along the screw’s axis. A coarser pitch means a larger gap between threads, which also translates to fewer threads per inch. National Course Thread uses a larger pitch than National Fine Thread, so it has fewer threads per inch and appears more “spaced out.” That coarser spacing makes NC quicker to screw in and more forgiving in dirty or misaligned situations, while NF’s finer pitch provides more precise adjustment and smoother engagement because there are more threads in the same length.

So, the correct distinguishing feature is the pitch: NC is coarser, NF is finer. The other statements don’t fit because the pitches aren’t the same, NF isn’t coarser, and both refer to imperial-style thread standards rather than metric vs imperial.