What type of nuts are these ?

[jcfx]

I recently bought a small parts cabinet from a a friend, the cabinet is the kind you used to find in
hardware stores, a sliding covered drawer with compartments, it also ( conservatively estimated) came with probably 150 lbs
of bolts, nuts and washers. I came across these in the haul, I've never seen these type of nuts, some seem to thread on
fine, some thread with a lot of difficulty, they have markings on them, are they some sort of vibration proof nut ?
Note they're not nylon insert type and they're bigger than I'll ever use.

mystery_nuts.jpg (103.39 KiB) Viewed 1099 times

[Russ Hanscom]

Self locking done by deforming the steel, should go on hard. No plastic to fail at higher temps.
You can also make your own, if you need a vibration proof nut. Either stand the nut on edge and hit it with a hammer, or squeeze it in a vise, the trick being how hard to hit or squeeze.

[jcfx]

Thanks Russ, I really don't have much use for nuts like that, especially the size of these ( 5/8 - 11 )
nyloc nuts work fine for me. Some ( heck, quite a few ) dont seem to 'seize up' as I thread them onto a corresponding bolt.
Guess it's a trip to the metal scrappers with these.

[Steggy]

The three circumferential “dashes” on the seat face indicate some of these nuts are grade-5, a medium-strength fastener like that available in well-stocked hardware stores.  Some nuts appear to be “prevailing torque” types, in which the nut is very-slightly distorted during manufacturing to make it resistant to vibrating loose. Such nuts are far superior to those using a nylon locking ring, as they can be reliably reused.

If you use the prevailing torque nuts to assemble something, be sure to liberally lubricate the threads before assembly, and also make sure the male threads are as least as hard as the nut.

[warmstrong1955]

IMG_0241.png (154.92 KiB) Viewed 944 times

[jcfx]

Steggy, Warmstrong, thanks for more info, that chart explains it all.

[Russ Hanscom]

For more details, see the Fastener Black Book, page 77, which shows 16 different nut markings; probably most of the commercial ones. About $33 at Amazon. More nut, screw, and bolt info than you can possibly use.