Guys, where does the 11 in 5/8–11uNC–2b come from?
Thread Content
I checked and it’s 11 threads per inch, but how was that determined? Could anyone give me some guidance?
The pitch is 11 teeth per inch (i.e., 2.309 mm), the same as the 1.25 mm pitch of M8 coarse-thread screws
The UNC (American coarse thread) standard specifies that for a diameter of 5/8, the pitch is 11 threads per inch. NPT threads also have a pitch of 11.5 teeth, which poses a problem for turners.
For a specified thread size, such as 5/8-11UNC-2B, the number 11 refers to the number of threads per inch. This value is determined by the thread specification standards. The American **Standard Association (ANSI) and the International Organization for Standardization (ISO) have established unified standards for different types of threads. In this example, 5/8 indicates that the diameter of the thread is 5/8 inch. 11 indicates 11 threads per inch. UNC indicates that the thread type is unified coarse thread, while 2B denotes the tolerance class for internal threads. Typically, the number of threads is determined based on the required tightening force and thread diameter. These standards are developed by specialized committees and engineers through research and testing to ensure safe and reliable connections. .
These are all the requirements of ASME B1.1. Use the image above; it’s the clearest.