Threads

[JHertzman@domain.elided]

While commenting on the SAE being formally an international organization,
r.m.bies wrote "The bolts bearing this designation are not metric, not 
whitworth, but in standard inches (fractional -- fine thread)".

I'm not sure when it happened, but the standard for "bolts bearing this 
designation" was long ago subsumed into the ANSI (American National Standards 
Institute) standards, apparently in at least two stages- the ASA (American 
Standards Association) in 1941 for part of it and ANSI in 1952 and 1955, as 
UNF. SAE has many standards (including grade markings for bolts, along with 
those of the ASTM), but the only "S.A.E. Standard Threads" I found are the 
ones for spark plugs, which are indeed metric and not 'inch'- in four sizes. 
The term "SAE threads" will undoubtedly survive in common use, as will 
"Whitworth" - - which isn't whitworth any more either. 

The ANSI standards also embrace metric bolts, but in a series which does not 
quite match those used on Alfas, which are - what? DIN? 

Sigh,

John H.

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