> Read this in the August issue of Road and Track
> [Tech Notes, by Dennis Simanaitis]
>
> Whitworth Madness
>
> By the early 1900s, the British Standard Fine (BSF) thread was adopted in
> parallel use, especially for applications where vibration was a problem
> with Whitworth hardware.
>
> And in 1924 Whitworth bolt heads were all downsized, with the new British
> Standard dimensions choosen so existing tools could still be used-but on
> different bolts. [could this be the source of the wrench size confusion?]
Has to be. The new head sizes are definately more reasonable, quite
akin to other systems. The pre-1924 sizes would have been
ridiculously large. So they made each hex head one size smaller and
did not rename the wrench. Us semi-educated (re: BSW and BSF) folks
on this side of the pond still remembered hearing the "bolt size =
wrench designation" rule and the rest is predictable. I fault the
Machinery's Handbook and wrench vendors for not pointing this out.
Thanks to Dennis for the article in R&T and to you for putting it on
the list. I meant to, but you know the drill: procrastinate and
forget.
>
> For instance, an old bolt head with 3/8-in. shank was the same size as a
> new bolt head with a 7/16 shank. So a 1924 Whitworth wrench would be
> labeled 3/8W 7/16BS. With older tools you had recall just what size fit
The ones I have seen just have the "3/8W" on them. If there would
have been two markings on the wrench, I could have figured this out
myself.
> which bolt. And whether the bolt was new or old. Or BSF. Or Metric.
> Or American Standard.
>
> There'll always be an England; I suspect because there'll always be some
> poor beggar trying to figure out which wrench fits.
>
> - Alan
--
phile@pwcs.stpaul.gov In real life: Philip J Ethier
Phone: 298-5324
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