[GreenKeys] 6-40 UNF and other wierd screw sizes

[Craig Sawyers]

> Actually a lot of the screws used by TTY are known as UNF
> (Unified National Fine).

Interestingly, the WWII German Lorenz SZ42 cipher machine also uses UNF
screws.  In fact whole chunks of it are identical to the Teletype 14
(particularly the selector mechanisms) - there was a business
relationtionship between Teletype and Lorenz at the time.

A couple of years ago I restored a (in fact *the only* remaining) Lorenz
machine, used by Field Marshal Kesselring at the time of the Normandy
landings.  Kind of strange to think that those apalling beach landings were
being securely communicated to Hitler's bunker in Berlin using Teletype
mechanisms.

Oh, and the wire guage in the transformers was SWG (standard wire guage) - a
British guage!  I can only think that we sold the Germans a job lot of the
stuff pre-war that they were working their way though, or that it was
captured stock from France or some such.  It was lousy - it had corroded
through in places in the middle of the winding pack necessitating rewinding
the tranformer (and smoothing choke).

Craig