Freeland tribune. (Freeland, Pa.) 1888-1921, 1895-02-07
THE ART OF SAW MAKING.
HOW AN AMERICAN TOOL HUM
BLED A TOLEDO BLADE.
The Fine Points of Good Handsaw
-Tempering is a Mysterious Pro
cess-The Band Saw.

|
Europe, and the modern steel
makers who have examined them with
professional criticism, while admiring
their beautiful workmanship and ex-
quisite art, unhesitatingly say that
none of them can compare with the
steel made to-day.
An American manufacturer of tool
steel declared that an American hand
saw was made of stronger, tougher
and better steel than famous Toledo
blade exhibited in France. He proved
his assertion, for a sword made of the
same steel from which the saw was
made stood the test to which both
swords were subjected, and then cut
the Toledo blade in two without nick
ing the edge of the American sword.
A good handsaw must of necessity
be made of good steel. Its temper
must be such that the thin blade
must spring in an even curve from
point to butt when it is bent 1t
must be elastic without being brittle,
tough without softness, and the steel
must be of an even temper. From
good, honest steel alone can such vir-
tues spring, and when carpenter has
such saw, polished to a silver luster,
rightly chung" well "set," with the
handle properly fitted to his hand, he
has n treasure.
The making of saws, from the tiny
scroll saw blade to the long pit saw,
from the diminutive buzz saw of the
dentist to the seventy-inch circular
used to slice up the redwood of Cali
fornia, requires the best of raw ma
terial and the most skillful and expert
of steelworkers.
The best Swedish and American
irons only are put in the melting pots
to make the steel, and powerful steam
hammers work the ingots before they
are rolled into plates, sheets and fiat
bars. The largest saw works in the
world are near Philadelphia.
The high perfection attained in the
| metal-workers' art is not in evidence
until the saw blade or disk, after being
cut to shape and having the teeth cut,
reaches the tempering and hardening
stage. The steel making, the "cog-
ging" of the ingots under the steam
hammering and the rolling mill are
interesting, and SO is the great shears
which cuts and shapes the saw blades
and circular plates for buzz saws. The
teeth-cutting machine is an attractive
piece of mechanism, but the harden
ing and tempering are done by men,
each one an expert, master of his
art.
When the saw blade reaches this
department it is soft. When bent it
is slow to return to its original shape,
and if bent beyond its elastic limit it
remains bent. To make saw of it
the blade must be tempered, an each
variety of saw must have q different
temper. The circular saw which is to
go through pine logs must have a
toughness, hardness and stiffness diff
ferent from the saw which is to cut
up steel rails into thirty-foot lengths
in rolling-mill. Still, the process,
the simple manipulation of the blade
and disk is about the same. The de-
sired results are secured by varia-
tion in temperatures in the hardening
and annealing furnaces, the time in
which the blades are kept in the fur
naces, the composition and tempera-
lures of the tempering baths.
The blades are first hardened by be-
ing heated and then suddenly cooled.
The greatest care must be exercised
in dipping the heated blade in the
water, for if one side cools quicker
than the other the unequal tension
distorts the blade and it is warped
The larger the saw the more difficult
is tho process.
The workman poises the blade over
the bath, watching it keenly. The
film of oxide on the steel changes color
as it cools, and when the proper tint
glistens in the blade it is plunged Mss
ing into the water. When it is cold the
blade is hard, but its toughness has
disappeared, for it is as brittle as
glass. A hammer blow will shatter
the steel to bits, for all its molecules
are in state OF extreme tension,
ready to fly apart on the slightest
provocation. To restore the tough
ness, the essential elasticity, the
temper must be "drawn," so the blade
must be heated again.
Here the mysterious art of tenn
pering is seen at its best. The work
man gives the steel just the right
amount of heat, and then withdraws
the blade from the furnace. Again
he watches the chameleon-like oxide
or skin; it changes and blends from
one color to another, sometimes
pigeons egg blue, an amber, straw,
yellow or deep-blue color. When
the proper color appears the blade is
dipped in the cooling bath, oil or
water or some secret mixture, anil it
is ready for another set of experts,
the men who handle the cold blade to
the proper thickness. This in itself
is n severe test of the temper, and a
saw blade which successfully passes
through this department not only re-
ceives that "tension" which the ham,
mering gives it, but can be guarau-
teed, SO far as the temper is concerned.
The hammering makes the blade or
disk true, perfectly flat and of uni
form texture. Up to this point the