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+--- Thread: 24UNJ vs 24UN threads (/thread-1309.html)
24UNJ vs 24UN threads - fullautomike - 04-12-2013
What did I do? I was going to make a 3/8 x 24 tpi threaded rod for a project, but the threads are not right!
I was using a full profile laydown threading insert. I used a 16ER 24 UNJ VC29. I think I messed up by using 24UNJ. It should have been a 24UN what's the difference? What did I do?? Thanks
RE: 24UNJ vs 24UN threads - wrustle - 04-12-2013
A "UNJ " is a jam thread.
We make some brass fittings for an aerospace customer with a 3/8-24 UNJ external thread. Once the fitting is installed, it will not vibrate loose. The root geometry on the thread is such that it creates an interference fit with the mating thread.
Best Regards,
Russ
RE: 24UNJ vs 24UN threads - the penguin - 04-13-2013
As I was told, as a young worker bee, "Nothing holds like a good cross thread"
RE: 24UNJ vs 24UN threads - wrustle - 04-13-2013
(04-12-2013, 10:16 PM)wrustle Wrote: A "UNJ " is a jam thread.
We make some brass fittings for an aerospace customer with a 3/8-24 UNJ external thread. Once the fitting is installed, it will not vibrate loose. The root geometry on the thread is such that it creates an interference fit with the mating thread.
Best Regards,
Russ
I probably should add that the above statement is true if in fact you are screwing a jam thread into a standard thread it will be virtually an interference fit due to the increased radius size of the root geometry.
However, if the external jam thread is installed in an internal jam thread dia. the resulting fit makes for an extremely strong thread, again due to the difference in the root geometry of the external thread. For tapping a hole to use a "jam" thread the minor diameter must be increased to accommodate the larger radius of the fastener.
Clear as mud? I thought so......
http://www.amtektool.com/NATool-Tap-EnginData6.pdf
RE: 24UNJ vs 24UN threads - fullautomike - 04-13-2013
Well I was just trying to cut regular old 3/8 x 24 tpi threads! I now remember buying the odd ball insert because it was cheap....I was going to use it to practice cutting threads. Well it was good practice, they look good...but I also learned a lesson
RE: 24UNJ vs 24UN threads - PixMan - 04-14-2013
Mike,
It would be pretty easy to recut the threads you made using the correct insert. I have one if you don't, and could take a spin on my bike down to see you and show you how to do it. Then we could go for a ride and you show me some of the nicer roads in your area, as I know there's a LOT.