ut of 10, this has been caused
by too low a forging heat, and when the blacksmith complains about
tools cracking, it is necessary to read this paragraph to him.

DON'T try to jam the tool into shape under a steam hammer with one
or two blows; take easy blows and keep the heat high.

DON'T have the tool curved at the bottom; it must lie perfectly
flat in the tool post.

DON'T harden from your forging heat; let the tool grow cold or
fairly cold. After forging you can rough grind the tool dry, but
not too forcibly.

DON'T, for hardening, get more than the nose white hot.

DON'T get the white heat on the surface only.

DON'T hurry your heating for hardening; let the heat soak thoroughly
through the nose of the tool.

DON'T melt the nose of the tool.

DON'T, as a rule, dip the nose into water; this should be done
only for extremely hard material. It is dangerous to put the nose
into water for fear of cracking and when you do put the nose into
water put just 1/2 in. only of the extreme white hot part into the
water and don't keep it too long in the water; just a few seconds,
and then harden in oil. We do not recommend water hardening.

DON'T grind too forcibly.

DON'T grind dry after hardening.

DON'T discolor the steel in grinding.

DON'T give too much clearance on tools for cutting cast iron.

DON'T start on cast iron with a razor edge on the tool. Take an
oil stone and wipe three or four times over the razor edge.

DON'T use tool holder steel from bars without hardening the nose
of each individual tool bit.

AIR-HARDENING STEELS.--These steels are recommended for boring,
turning and planing where the cost of high-speed seems excessive.
They are also recommended for hard wood knives, for roughing and
finishing bronze and brass, and for hot bolt forging dies. This
steel cannot be cut or punched cold but can be shaped and ground
on abrasive wheels of various kinds.

It should be heated slowly and evenly for forging and kept as evenly
heated at a bright red as possible. It should not be forged after
it cools to a dark red.

After the tool is made, heat it again to a bright red and lay it
down to cool in a dry place or it can be cooled in a cold, dry
air blast. Water must be kept away from it while it is hot.

CHAPTER XI

FURNACES

There are so many standard furnaces now on the market that it is
not necessary to go into details of their design and construction
and only a few will be illustrated