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
