Understanding Imperial Threads
Understanding Imperial Threads
(OP)
Hi Guys,
I have been working with Imperial for the first time as I have always been working with Metric. I have a drawing with the thread details of (.75-16 UNF - 2B .63MIN - FULL THD) This is a male thread and I didn't understand the full detail of this thread after several attempts in Google.
Now I am creating a female thread to the above spec but unsure what can it be? as I don't know the meaning apart from the UNF-2B Standard.
I would appreciate for your help to make myself understand or refer to some notes.
Thank you
regards
Rodney
I have been working with Imperial for the first time as I have always been working with Metric. I have a drawing with the thread details of (.75-16 UNF - 2B .63MIN - FULL THD) This is a male thread and I didn't understand the full detail of this thread after several attempts in Google.
Now I am creating a female thread to the above spec but unsure what can it be? as I don't know the meaning apart from the UNF-2B Standard.
I would appreciate for your help to make myself understand or refer to some notes.
Thank you
regards
Rodney





RE: Understanding Imperial Threads
Thanks
RE: Understanding Imperial Threads
RE: Understanding Imperial Threads
RE: Understanding Imperial Threads
Basically true, but the fit designator "-2B" denotes a class 2 fit for an internal thread, whereas the matching external thread fit designator would be "-2A". To be fair, the thread fit designator is typically assumed to be class 2 and whether it's internal or external is also typically apparent from the drawing or application, so the fit designator is not strictly necessary unless you are calling for a class 1 or class 3 fit.
The dimensions indicate:
.75-16 UNF-2B .63 MIN- FULL THRD
In order, that's:
[.75" Major diameter of external threads]-[# of threads per inch, also called "thread pitch" or just "pitch] [callout for standard used to define the thread (UNC, UNF, etc)]-[fit class designator] [length of bolt/screw]-[length of thread]
So here you have a 3/4" diameter screw with 16 threads per inch, defined by the Unified National Fine thread standard, with a class 2 fit (class 1 is loose, class 2 is the most common, class 3 is very tight/precise) of internal threads (the "B" in the callout), with a minimum shank length of 0.63" and the entire length of the shank threaded (as opposed to some bolts you'll see that have a portion of the shank unthreaded).
RE: Understanding Imperial Threads
RE: Understanding Imperial Threads
Machinery's will also probably have enough to get you going.
Thread designation on drawings is often done poorly or even incorrectly and every now and then that can be a problem so I encourage you to learn how to do it properly.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Understanding Imperial Threads
Helped me a lot.
regards
Rodney
RE: Understanding Imperial Threads
Petrotrim Services, LLC
www.petrotrim.com
RE: Understanding Imperial Threads
Petrotrim Services, LLC
www.petrotrim.com
RE: Understanding Imperial Threads
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?