Re: grade 8 (was Re: Engine stand)

[christian147@domain.elided]

Huh,  common UN thread forms are crap.  even rolled they are nothing but
a stress riser waiting to fracture.  In conditions of cyclical stress you
have to use special steel or a over sized bolt.  You have to go to "J"
thread form to even come close to the strength of Whtworth. 
Lots of counterfeit hardware on the market, most from Asia.  Do not count
on the markings on the bolt head unless you know the manufacture.  Be
careful of "Better then grade" hardware, it has a higher tensile by being
harder, so is more prone to stress fracture.  As you say aircraft supply
houses are a very good source of quality (AN) hardware.  I use Aircraft
Spruce, if you know of a better one please enlighten me.


Chris Hall


 >BTW-- there isn't a metric thread standard out there--be it DIN, JIS, 
some
>french or italian bologna,  BS, or Whitworth, that comes even CLOSE to
>being as GOOD a thread standard as the good old ANS and SAE stuff is---
>This is just something that we Yanks happen to have done  RIGHT.
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