[GreenKeys] Metric system

[John Nagle]

> Date: Tue, 4 Jul 2017 01:12:19 -0400 > From:WA5CAB at cs.com
> Subject: Re: [GreenKeys] The Metric System (was  Independence Day
> Message-ID:<7edd7.d4fd503.468c7db3 at cs.com>
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> 
> It was probably invented by French and/or Germans but as far as perfecting
> it, unh unh! Just take the ISO Metric threaded fastener system. Worst
> real-world threaded fastener system ever devised. Thread pitch is too fine. Hex
> nuts and hex cap screw heads are too small. Screw heads are too small. Screw
> slots are too narrow. The system is only usable in (a) a Clean Room or (b) a
> "total consumer" economy where when something stops working instead of
> fixing it, it goes to a land fill and a new one (that usually doesn't work as
> well as the old one) has to be bought.

    Teletype machines, at least those from the 14/15 era, use mostly
Unified National Fine threads.  Almost everything else in US practice,
except some guns, uses coarse threads.  Teletype also used narrower
screw slots than standard.  Those are design decisions also seen in
modern metric practice.

				John Nagle