[SML] Thread projection

[Steven Hood]

I would guess that, for self-locking (Nylocks, especially) that they (any manufacturer) would try to limit how many turns the nylon (or whatever the lock) is subjected to, as the locking tension would be diminished by over-use. I've seen nylocks worn out from use so that the nylon doesn't even engage the threads. I've also seen captive lock washers (the toothed variety) smashed under so much torque that they flatten out and fall off when the nut is removed later for some adjustment to the assembly...
That's just my tuppence,
Steven R Hood


On Friday, September 19, 2014 3:38 PM, Loren Schreiber via Stagecraft <stagecraft at theatrical.net> wrote:
What I was really looking for was a US standard or a regulation to cite. 
Frankly, I'm a little surprised that there isn't one.

There is this from the FAA, who take great pride in regulating 
everything. In regards to self-locking nuts:

"After the nut has been tightened, make sure the rounded
or chamfered end of the bolts, studs, or screws extends
at least the full round or chamfer through the nut. Flat
end bolts, studs, or screws should extend at least 1⁄32
inch through the nut."

And there is the DIN 78 specification which specifies a 3 thread 
projection for self-locking nuts.

-- 
Professor Loren Philip Schreiber
Technical Director
School of Theatre, Television, and Film
ETCP-T Certified Rigger #1095
CA Contractor License #966080


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