UNRC Threads?
UNRC Threads?
(OP)
Has anyone ever heard of UNRC threads? I have been told the "R" means rolled threads and I have also been told the "R" designates a special root radius thread form. What I really need to know is if a UNRC Class 2 or 3 bolt will fit without interference into UNC class 2 or 3 threaded holes.
Thanks for helping.
Thanks for helping.





RE: UNRC Threads?
The R stands for "rolled" which gives you a special root radius. Basically, because these threads are rolled and not cut, the grain structure of the metal changes making these threads slightly stronger than regular UNC threads.
If Corypad is around, hopefully he can elaborate more.
--Scott
For some pleasure reading, try FAQ731-376
RE: UNRC Threads?
RE: UNRC Threads?
Even at maximum material condition you will have no problems with fit and interchangability for the two systems. They are designed to be fully compatible.
Dick
RE: UNRC Threads?
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: UNRC Threads?
V/R
T
RE: UNRC Threads?
RE: UNRC Threads?
Thanks for the history on the "R" designation.
It seems like common knowledge to you, swertel,israelkk, Screwman and Cory that the UNRC thread will mate with the UNC threads, yet without going through the geometry which you all have now made me aware of, I would never have known this. The "average" designer, in making bolt selections, does not need to delve into thread form geometry, so how would the average designer know that UNRC will mate with UNC? What text, reference or footnote did I miss along the way?????
T
RE: UNRC Threads?
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: UNRC Threads?
"UNR applies only to external threads; the difference
between UN and UNR threads, in addition to
designation, is that a flat or optional rounded root
contour is specified for UN threads, while only a
rounded root contour is specified for UNR threads."