Which statement best describes Acme threads?

• A. They have a 60-degree thread angle.
• B. They have a 29-degree thread angle with thread height equal to half the pitch.
• C. They are a square thread form.
• D. They are used only for pipe sealing.

Answer: (B)

Acme threads are a trapezoidal screw thread used for power screws and leadscrews. They feature a 29-degree thread angle, which provides a strong flank and smooth engagement, and the thread height is about half the pitch, giving a robust profile without making the threads too deep. This combination makes Acme threads easier to machine and harder to wear than sharper V-threads, while offering good load-carrying capability. They aren’t 60-degree V-threads, they aren’t a square-thread form, and they aren’t limited to pipe sealing (pipe threads follow different standards like tapered NPT or BSP). So the description that matches Acme threads is the 29-degree angle with thread height approximately half the pitch.