[Shop-talk] Metric Hardware

[Randall]

> It's actually more complicated than that, though.  The bolts that we
> call "Whitworth" on our LBCs aren't really.  They're British Standard
> Whitworth (BSW), or British Standard Fine (BSF).

Except the ones that are British Association (which on a TR3 is the majority
of the "Whitworth" threads).

>  So a 1/4-20 whitworth bolt has a head that you'd
> find on a 5/16 BSW or BSF bolt,

Are you sure about that ?  My understanding is that a 1/4 BSW bolt has a
larger head than a 1/4 BSF bolt. 
IOW, BSW is effectively the same as the earlier "Whitworth" (in much the
same way as UNC is the same as NC).

See, for example,
http://www.internationalcockpitclub.org.uk/articles/article_threads.htm

Randall 
(Tedious but unavoidable disclaimer follows) 






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