Thread calculations
Thread calculations
(OP)
Is it right to say :
minimum dia of the internal thd. = (major dia. of internal thd.) -(5/8 *pitch * cos30)
for an UNC or UNS thd?
Thanks
minimum dia of the internal thd. = (major dia. of internal thd.) -(5/8 *pitch * cos30)
for an UNC or UNS thd?
Thanks





RE: Thread calculations
What I calculated was for a UN, height of a thread is basically 5/8 times its sharp thread height (with the crest and trough flattened or rounded for engagement) so that comes out to .0169in, to get minor dia, I would sub two times of this from the major and end up with 11.591.
Is this correct? I believe this might be directly mentioned in the ANSI/ASME B 1.1-1989 standards (for threads over 4in in dia) but I dont have that.
Thanks
RE: Thread calculations
RE: Thread calculations
RE: Thread calculations
Dick
RE: Thread calculations
size, that plus the amount of oversize
that drill might make would give you
the actual rather than the theoretical
size which is probably more important.
RE: Thread calculations
RE: Thread calculations
RE: Thread calculations
-1/number of threads.
example 1" 8 thread = 1"- 1/8 = 7/8" drill.
this is very close for all thread sizes. don't kmow if it is close enough for your needs.
bobc