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Re: [Rollei] Tripod threads

At 04:44 PM 9/24/01 -0700, Jerry Lehrer wrote:
>Today I checked all my camera tripod sockets and bushings
>on an optical comparator and I get the following results from
>all of them:
>    1/4-20 tpi. 60 +/-2 degree angle
>    3/8-16 tpi  60 +/-2 degree angle
>None exhibited a 55 degree thread form.

Thanks, Jerry.  This makes sense.  I suspect the International Standard
adopted in 1889 WAS the Whitworth thread and that this was used for some
years -- Whitworth DID remain the norm in scientific apparatus until the
Second World War but, outside of that, was never readily available in the
US.  I suspect the US guys simply ignored the standard somewhere along the
way -- say, the 1920's? -- and went their way with UNC and its 60º slope.

But I haven't a doubt that the original standard -- and, probably, the
current standard! -- calls for BSW.


msmall    FAX:  +540/343-7315
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