What is the pitch diameter for a 5/8-18 UNF 3A thread according to the Machinery Handbook?

The pitch diameter for a 5/8-18 UNF 3A thread is crucial for ensuring proper fit and function between mating parts. In threading, the pitch diameter represents the diameter where the width of the threads and the grooves are equal. For a 5/8-18 UNF thread, the standard measurements are defined in reference materials, such as the Machinery Handbook, which provides the correct ranges for various thread types.

The specified range of .5889 - .5934 aligns with the recognized standards for a 5/8-18 UNF thread, making it the correct choice. This measurement falls within the acceptable tolerance range defined for internal threads classified as 3A, which ensures a proper fit with a corresponding external thread with a 3B tolerance.

The other ranges mentioned do not correspond to the established dimensions for a 5/8-18 UNF thread, which may lead to issues in creating a secure and functional connection between threaded components. Therefore, understanding the specific pitch diameter and its importance in thread fitment is critical for achieving the intended mechanical performance in CNC machining applications.