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Re: [Rollei] Tripod threads
- Subject: Re: [Rollei] Tripod threads
- From: Marc James Small <msmall >
- Date: Mon, 24 Sep 2001 22:48:06 -0400
- References: <B7D489B4.1377C%bob >
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
Cha robh bàs fir gun ghràs fir!