I missed the staff meeting but the minutes show
(Bob Edwards) wrote back on 23 Aug 2004
06:31:29 -0700 in rec.crafts.metalworking :

Did you know there is a drawing in DaVinci's papers of a file-cutting
machine which looks similar to (but less complicated than) the picture
I posted from the Musee des Artes et Metiers? I don't know if it was
ever constructed, but the drawing shows the concept of doing this by
machine was around very early.

I think it's not so much that the procedures for heat treatment and
tempering of steel were not known prior to the Sheffield makers' use
in the mid-1800's; more that good steel was hard to come by.

The basics of hardening steel have been known dating back to ancient
times by swordmakers and other metalsmiths -- what was new in the
mid-1800's were the new steel-making proceses, which greatly increased
the availablilty of good steel.

That is the rub. The real change wasn't just cheap iron, but cheap
steel. I've been told that prior to the 1600s, iron cost like silver, steel
like gold - at least in terms of comparable purchasing power. We've
dropped the cost of steel from where it was just used for cutting edges, to
now we make nails of it, and other "disposable" items.

tschus
pyotr


--
pyotr filipivich.
as an explaination for the decline in the US's tech edge, James
Niccol wrote "It used to be that the USA was pretty good at
producing stuff teenaged boys could lose a finger or two playing with."