On Mon, 21 Sep 1998 neil.cairns@virgin.net wrote:
> It was common in the early Industrial Revolution for companies to have
> their own theads on nuts and bolts. In the UK three had eventually been
> standardised for the motor industry, British Standard Fine, BSF; British
> Standard Whitworth, BSW; and British Standard Pipe Thread, BSP. All used
> the Whitworth thread form. The USA was developing its ANF and ANC
> system, but the European Continent had mant variations of metric
> threads, that would eventually lead to the ISO Metric system. There were
> other threads, British Association, BA, a tiny system used in
> instruments, and some UK firms were coyping the Americans, but calling
> the system UNF and UNC, Unified Coarse and Unified Fine.
The UNC/UNF thread system was a result of World War II, during which
large quantities of machinery for the British war effort were manufactured
in the United States. That isn't exactly early Industrial Revolution.
Well, not to those of us who qualify for membership in the OF's Club
anyway. :-)
> Hotchkiss had their own metric thread system for the manufacturer of
> their guns. They continued to use these taps and dies on the engines
> they made. But as time advanced, the more logical system on a 'Unified
> Common Thread' for all machines was developed. In the UK the heads of
> ALL the nuts and bolts were made BSW sizes. This was handy as the BSF
> head size for the BSW equivalent was the next size down. This mattered
> not, as the mechanic only needed one set of spanners. Even BSP used the
> spanner sizes, ( on sump plugs, etc.)
The metric thread system used by Hotchkiss wasn't unique to Hotchkiss.
It was also known as "French Standard Metric", and was used in France (and
several other countries, but I've forgotten which) until the adoption of
the more sensible ISO Metric standard.
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Chip Old 1948 M.G. TC TC6710 NEMGTR #2271
Cub Hill, Maryland 1962 Triumph TR4 CT3154LO
fold@bcpl.net
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