ago the machinist appreciated a good cold chisel. He had to do
all his heavy planing and shaping with them, and he took care to
have the best and keep them in shape. If a man was going to chip
the teeth of a big bevel gear, in order to remove the scale, he
would be pretty apt to look around for the very best cold
chisels he could get hold of, and then he would keep them sharp.
When you make a cold chisel, get a good quality
of octagon cast steel. It is a pretty good rule “to sample all
the tool steel that comes into the shop and make cold chisels of
the samples.” If steel will stand the cold chisel racket, it is
good enough for any tool.
Our grandfathers used to test all their new
steel by drawing a piece of it down to an eighth of an inch
square, and then taking a very strong heat, in fact, burning the
extreme end. Then they cooled and broke in pieces with the
They had a chance to see just how much heat it
would stand without getting “rotten,” also at what heat it would
harden, and whether it would spring in hardening.
Nobody knew then what a piece of steel would be
like until he had tested it. It “might harden, or it might not.”
Now-a-days you get the same brand from the same maker, and are
reasonably sure of getting the same steel, but there is a
difference, as the tool maker often knows to his sorrow.
Don’t try to draw steel to smaller sizes in hope
of improving the chisel by “hammering.” “Hammered” steel
now-a-days, when that hammering is done by the smith on his
anvil consists of “more talk than cider."
The old chaps long ago used to improve the steel
of their time by judicious working and hammering, but tool steel
of to-day is so homogeneous that I would rather take it in the
bar than after the smith has “monkeyed” it. Don't try to work a
cold chisel too cold. There is a saying that the “devil gets the
smith who hammers cold iron, or hot steel,” but don’t hammer a
cold chisel after it is cold. You may hammer it enough to get
hammer marks out, but don't try to draw cold steel.
I have seen smiths heat a drill or chisel for
about 3/8", and then strike 300 pound blows to draw the steel,
just back of the hot place. It causes terrible strains in the
chisel, and if a fire crack comes in and about half the width of
the chisel breaks off, they pitch it into the scrap heap or
tail-race and cuss the man that made “that poor steel.”
Everybody writes in the papers against heating
steel too hot, or “burning it,” but half the trouble with cold
chisels is caused by too little heat. Cannon will be destroyed
in time by the action of blows struck by the exploding powder.
How long would one last if it were put under a
big 100 ton steam hammer and struck hard enough to disarrange
the structure of the iron or steel?
You would not have to fire it many times after
such treatment before it would “let go” and kill at both ends.
Heat steel as hot as it will bear, and work it
while hot. If you wish to work 7/8” of the end of a chisel, do
the heating back of where you intend to hammer. Heat an inch and
a half of the tool. It takes a trifle longer, but you can work
it much better. It will hold the heat and work easy.
Don't try to temper a chisel with the remains of
the forging heat. Use a fresh heat, for tempering, and heat
enough to harden. Leave all tempering “medicines” for somebody
else; if you cannot get a temper with good fire and water, you
have mistaken your vocation, and had better try some other
When tempering cold chisels, or any other steel
articles, heat to a very dull red and rub with a piece of hard
soap, then finish heating and harden in clear, cool water. The
potash of the soap prevents the oxygen of the atmosphere from
uniting with the steel and forming rust or black oxide of iron.
The article will need no polishing to enable the colors to be
seen. This will be appreciated when tempering taps, dies, or
various complex forms not easy to polish.
Never “upset” a cold chisel. It
sure death to the steel. Many of us have lived on a farm and
know something about a bundle of nice, straight, clean straw. If
you work it intelligently you can tie it up into stout bands for
binding other bundles.
You can take hold of the ends of that straw and
draw out a handful without harm to the straw, After you have
drawn out half that bundle a foot or so, try to drive it back;
every blow breaks the straw, cripples and doubles it up, and it
will hardly bear its own weight, to say nothing of making a band
for other bundles.