Thank you, Jim, for a clear, concise explaination of the heat-treat
metallurgy and alloy analysis. Thanks, too for the Tool Steel sources. 

        One question I've been trying to answer: O-1's critical temp range
is 1450 - 1500F. Will the hardness be different if quenched from one extreme
or the other or does the steel harden thoroughly from any temp in that
range? (Okay, two questions) And how long should a piece remain at critical
temp to fully transform?

        I have one nit to pick about the advantage of the water hardening
steels*. The softer, unhardened core may provide some shock-absorbsion in,
say, a chisel blade, but I see no such advantage in a plane blade where the
shock load is taken by the cantilevered cutting edge alone and not the rest
of the blade. The thin, beveled edge would be hardened throughout and would
not have a soft core to benefit from. IMHO, the traditional lamination of
blades was practiced to conserve the rare and hard to make/obtain tool steel
by limiting its use to the business end of the blade. A through-hardened,
all tool steel blade like a chisel, is extremely hard to break without
subjecting it to horrible, abusive leverage-loads. To break even one of our
3/32" thin blades, requires standing it in the bench vise (metal one...) and
hitting it hard with a big hammer (it breaks with ballistic intensity --
don't do this at home!)

        I'm going to get on the phone now and try to track down some W-1
flat stock for testing. I'll keep y'all posted if I find out anything
interesting.
  
*>In my opinion the best plane blades are made of water hardening steel.  In
>the best case, and with thick blades, the blade is not fully harden leaving
>a softer tougher core.  The advantage of this can be seen in blades that
>have been steeled (Ie very old blades and all higher quality Japanese
>ones). 

Thanks again,

Ron

Ron Hock  (rhock@m...)
http://www.mcn.org/a/rhock/hockhome.htm
Hock Handmade Knives  16650 Mitchell Creek Drive  Fort Bragg, CA  95437
(707) 964-2782  fax (707) 964-7816