Heat Treatment Of Lathe Planer And Similar Tools
Category: HIGH-SPEED STEEL
FIRE.--For these tools a good fire is one made of hard foundry
coke, broken in small pieces, in an ordinary blacksmith forge with
a few bricks laid over the top to form a hollow fire. The bricks
should be thoroughly heated before tools are heated. Hard coal
may be used very successfully in place of hard coke and will give
a higher heat. It is very easy to give Blue Chip the proper heat
if care is used in making up the fire.
FORGING.--Heat slowly and uniformly to a good forging heat. Do
not hammer the steel after it cools below a bright red. Avoid as
much as possible heating the body of the tool, so as to retain
the natural toughness in the neck of the tool.
HARDENING.--Heat the point of the tool to an extreme white heat
(about 2,200 deg.F.) until the flux runs. This heat should be the highest
possible short of melting the point. Care should be taken to confine
the heat as near to the point as possible so as to leave the annealing
and consequent toughness in the neck of the tool and where the tool
is held in the tool post.
COOL in an air blast, the open air or in oil, depending upon the
tools or the work they are to do.
For roughing tools temper need not be drawn except for work where
the edge tends to crumble on account of being too hard.
For finishing tools draw the temper to suit the purpose for which
they are to be used.
GRIND thoroughly on dry wheel (or wet wheel if care is used to prevent
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