1/2 x 28 UNF

For those who care, I stumbled upon and bookmarked the resource. More than I want to know......

Technical Information, Thread Gages, Ring Gages, Screw Plug Gages

www.ring-plug-thread-gages.com www.ring-plug-thread-gages.com
and to further confuse myself I found;
www.brownells.com

AR-15/M16 FLASH SUPPRESSOR DIE | Brownells

A must when threading custom barrels or chasing threads on standard barrels. Use to make custom supressors or clean up existing factory threads. Custom-made to factory specs. SPECS: High-speed steel. AR-15/M16 - .500"-28 thread, 1" dia. body. AR-1...
www.brownells.com www.brownells.com
Restating........I'm working on an antique American motorcycle, I have no drawings. Good luck getting parts. The threads are neither Witworth or Metric. My objective was to verify that the threads that I cut were; 1/2 x 28 TPI (UNF) and I would confirm that by using a tap and die of that size. My forum friends have schooled me on the fact that 1/2 x 28 UNF threads does not exist, BUT 1/2 x 28 UNEF does (something that I have to accept)
I appreciate every response and the education!
 
It really isn't us telling you that a 1/2-28 UNF doesn't exist. It literally doesn't exist according to the ASME standard for the UN designation. I guess it is hard for us to understand why you think it does exist. Also, under the ASME UN thread designation there are tolerance classifications for internal and external threads. Maybe this is what you are struggling with? My recommendation is for you to stop searching the internet for confusing articles and purchase a Machinery's Handbook with all the correct technical information you'll ever need. The book is chuck full of all the correct ASME specs and more. I use mine all the time, just recently for pipe thread, size, and fitting information. Money well spent. Hope his helps.
 
RandyM said:
It really isn't us telling you that a 1/2-28 UNF doesn't exist. It literally doesn't exist according to the ASME standard for the UN designation. I guess it is hard for us to understand why you think it does exist. Also, under the ASME UN thread designation there are tolerance classifications for internal and external threads. Maybe this is what you are struggling with? My recommendation is for you to stop searching the internet for confusing articles and purchase a Machinery's Handbook with all the correct technical information you'll ever need. The book is chuck full of all the correct ASME specs and more. I use mine all the time, just recently for pipe thread, size, and fitting information. Money well spent. Hope his helps.
Click to expand...
Some of the books that I have, (before ASME Standards), do list it as UNF also. And yes, Machinery’s Handbook is a Great Resource. I have several editions. My 12th has a lot of stuff that my 25th omitted because it is not very common, such as Stub Acme Screw Threads.
 
I would have to agree with OTmachine. I have several machines built from the early 1900’s to the late 1930’s that have threaded fastener styles that are now considered obsolete. As such they no longer appear in current technical publications.

If you look at older Machinery’s Handbooks you’ll see there are literally dozens of thread profiles that are no longer manufactured. That doesn’t mean they don’t exist. It mearly means they are no longer popular and difficult to find.
 
I’ll add a bit to Randy’s suggestion for Machinery’s Handbook, I don’t know if they still sell it this way, but I have the pdf version and I can print the pages I need and bring them to the shop and not worry about getting a book dirty. I created a binder with my most used information and just add to it each time I need something new.
 
I also have the H-28 handbook on threads, released from Mil-Spec, that I have scanned to pdf. If I break it up into 4 files, I could post it here, if it is okay with the moderators. It is a Good resource, which is why I bought it.
 
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