What is the difference between coarse and fine threads in fastening?

What is the difference between coarse and fine threads in fastening?

• A. Coarse threads have more threads per inch than fine threads.
• B. Coarse threads are used when high precision is required.
• C. Fine threads have more threads per inch and provide better sensitivity to vibration.
• D. Coarse threads are always stronger in all materials.

Answer: (C)

The main idea here is that thread pitch distinguishes coarse from fine threads. A finer thread has more threads per inch (smaller pitch), so more thread engagement along the fastener. This allows for finer adjustment of the clamp load and greater resistance to loosening from vibration because the load is distributed over more threads and more surface contact. That’s why the statement about fine threads having more threads per inch and offering better control under vibrating conditions is the best description. Coarse threads are quicker to assemble and resist dirt/damage better, but they don’t provide the same precision. And saying coarse threads are always stronger or that they’re used when precision is needed isn’t accurate.

The main idea here is that thread pitch distinguishes coarse from fine threads. A finer thread has more threads per inch (smaller pitch), so more thread engagement along the fastener. This allows for finer adjustment of the clamp load and greater resistance to loosening from vibration because the load is distributed over more threads and more surface contact. That’s why the statement about fine threads having more threads per inch and offering better control under vibrating conditions is the best description. Coarse threads are quicker to assemble and resist dirt/damage better, but they don’t provide the same precision. And saying coarse threads are always stronger or that they’re used when precision is needed isn’t accurate.