[rollei_list] Re: ?? True Sizes of Tripod Mounting Holes

At 10:57 PM 8/28/2007, Jerry Lehrer wrote:
>RUGers
>
>As usual, Richard is right.  The thread form is 60 degrees, NOT the
>Whitworth 55 degrees.
>
>The word Whitworth makes my skin crawl, thinking of my early days
>working on my MG TD,
>Cad-Allard,  Jaguar or AC-Bristol.  Al those used a mixture of thread
>und wrench standards.
>I only reached fastener sanity with Porsche and the Metric system.

Jerry
You are an engineer and you should appreciate this. Whitworth was the ONLY engineer-designed thread system in which cost of production was not made a factor. The team designing it was just told to make the best thread system they could and the one least likely to come unscrewed under stress. All later systems (DIN, UN, &c) were made by engineers ordered to make the cheapest possible thread system which was reasonably decent. DIN was reworded in the Second World War to decrease its cost of production, and the UN system was specifically intended as an economical system of fasteners to speed up war production while providing a common thread-system for use by all Allied nations.
Incidentally, Whitworth was the only thread system in use in microscope production until the Second World War even for Japanese or Soviet made gear. Even today, many parts of a microscope, such as the objective mounting, are still in Whitworth. (That objective thread, incidentally, is the Royal Microscope Society Thread-Mount, the so-called, "Royal Screw", of 0.795 inches by 36 turns-per-inch Whitworth -- I had a friend call me this evening and ask me for it, so its dimensions are fresh in my mind.) 

Marc


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Cha robh bàs fir gun ghràs fir!

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