Thread Relief Constant

[joshpjost]

Can someone identify thread relief constants for sizing thread chamfers and reliefs? I have an old table that provides two thread relief constants, A & B, based on pitch. Here's a similar chart:

http://www.bjg-design.com/designbook/thread_reliefs_htm.htm

I would like to know how to calculate the constants, or at the very least, understand where they are derived from. I have perused ASME B1.1 and cannot seem to locate based on thread data, but I must be missing something.

Any help would be greatly appreciated.

-J

 

[CheckerHater]

Wow, great chart!

This kind of information falls under "accepted practices" category.
It belongs to gray area between drafting and manufacturing standards and sometimes cannot be found in any of them.

Your chart is more likely "borrowed" from company manual created by "big guys" like car companies or GE.
I seriously doubt if underlying formulas were ever disclosed to the public.