huangyhg

threads per mil-s-8879 (j-series)
i am trying to find standard (ms?) bolts that use "j" series threads.
i can't seem to find any stock bolts that use this thread. i did a google search for "threads per mil-s-8879" and all that came up was an earlier thread on this forum (that unfortunately didn't answer my question).
any ideas?
you'll need to get a listing of specifications for fasteners from the sae, a sample:
as9696c bolt, machine - double hexagon extended washer head, pd shank, corrosion and heat resistant steel, uns n07001, 165 ksi min,
.1900-32 unjf-3a
as9576b bolt, machine - double hexagon extended washer head, drilled, pd shank, silver plated, corrosion and heat
resistant steel, uns s66286, 130 ksi min, .3125-24 unjf-3a
etc. etc.
there were also a nas series of fasteners using unj threads, nas1351 comes to mind. hmm, now that i check (type nas into ihs site), those were unr series threads, not j.
cculp..
sae as8879 thread spec replaced mil-s-8879 and mil-s-7742 in most instances... with a few specific exceptions. faa ac21-41a "replacing mil-s-8879c with sae as8879" discusses the subject in-depth.
virtually all fine-thread an, ms [nasmxxxxx spec] and nas bolts/nuts use these (3) thread specs. note: for large diameter parts this spec probably wont apply.
for a relatively complete listing of common aeropace fasteners [bolts, screws, nuts, etc], with good illustrations, go to the following sps website and download the "aerospace fasteners" file [7+mb]. note: in the back of the document are references to "very old-technology" and obsolete part specs.
thanks for the info! i was reading the as8879 revc, as well as an article on the changes from mil to as while you were writing the response, wil. i grabbed that fastener guide from sps, that should come in handy.
i am probably looking at 1/4" hex bolts/nuts; although if i can get down to .190 and maintain the fatigue strength (and everything else), i will go with the smaller size.
i appreciate the pointers from both of you, and i can now continue my calculation scribblings.
be careful, not all fine/course threads are the same.
there are still threads made to mil-s-7742 (which are cut threads) as well as the mil-s-8879 (which are rolled threads).
i cannot quite remember off the top of my head, but in a tolerance stack-up a male/female combination will not fit. i don't re
quote:
i am trying to find standard (ms?) bolts that use "j" series threads.
ms9556 double-hex .190-32 unjf-3a
ms9555 double-hex .164-36 unjf-3a
ms9111 double-hex .250-28 unjf-3a
heckler
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thanks for the tips. i guess i should close out this thread saying i've found what i'm looking for.
it looks like i need either:
ms9783 or ms9784
i am designing a threaded part with .2500-28 unjf-3a threads. the threads need to be rolled and i'm not sure which spec i can/should use to define the rolling process. i was going to use as8879 to define the threads. any thoughts?
rolled threads are the "controlled root radius" threads,
as8879,
thanks.

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