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Bolt Specs....?

Bolt Specs....?

Bolt Specs....?

(OP)
I have a drawing with a bolt description:

2x4 LG S.F. Tap Bolt - 8thd

Can anyone give me a heads-up as to what these terms mean?

Thanks a bunch.

RE: Bolt Specs....?

Assuming all other dimensions on the drawing are in imperial units, I would normally interpret it as a notation for 2" diameter thread, 4" long ("LG"), 8 tpi (threads per inch ["thd"])which would probably be defined by the Unified Constant Pitch Series.
However the term "S.F.Tap Bolt" appears to be an abreviation of Self tapping bolt, and I haven't come across a self tapper this big before !

RE: Bolt Specs....?

In the trade "Tap Bolt" normally referees to a bolt threaded all the way to the head.
  
I asked around and no one picked up on the "S.F." part, still asking.

RE: Bolt Specs....?

(OP)
Thanks guys.

"thd" is the same as "tpi" (threads per inch)?  I would never have guessed that.

RE: Bolt Specs....?

That's is just another part of the vernacular around the fastener supply houses.  I have very seldom heard the term threads per inch used, it is always "give me 20 2"x12" 8 thread, 7 thread, or what ever.  

Another quirk is the length callout on fasteners, especially studs.  If nothing is said the length will be end to end which takes a little usable thread off due to the chamfer.  More and more people were calling out 1st to 1st , the first good thread.  Now that material cost has gone through the roof the callouts are back end to end.    

RE: Bolt Specs....?

(OP)
Any recommendations on where to purchase bolts of this size?

Thanks again.

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