Hardening Carbon Steel For Tools

: The Working Of Steel

For years the toolmaker had full sway in regard to make of steel

wanted for shop tools, he generally made his own designs, hardened,

tempered, ground and usually set up the machine where it was to

be used and tested it.

Most of us remember the toolmaker during the sewing machine period

when interchangeable tools were beginning to find their way; rather

cautiously at first. The bicycle era was the real beg
nning of

tool making from a manufacturing standpoint, when interchangeable

tools for rapid production were called for and toolmakers were in

great demand. Even then, jigs, and fixtures were of the toolmaker's

own design, who practically built every part of it from start to


The old way, however, had to be changed. Instead of the toolmaker

starting his work from cutting off the stock in the old hack saw,

a place for cutting off stock was provided. If, for instance, a

forming tool was wanted, the toolmaker was given the master tool

to make while an apprentice roughed out the cutter. The toolmaker,

however, reserved the hardening process for himself. That was one

of the particular operations that the old toolmaker refused to

give up. It seemed preposterous to think for a minute that any

one else could possibly do that particular job without spoiling

the tools, or at least warp it out of shape (most of us did not

grind holes in cutters 15 to 20 years ago); or a hundred or more

things might happen unless the toolmaker did his own hardening

and tempering.

That so many remarkably good tools were made at that time is still

a wonder to many, when we consider that the large shop had from 30

to 40 different men, all using their own secret compounds, heating

to suit eyesight, no matter if the day was bright or dark, and then

tempering to color. But the day of the old toolmaker has changed.

Now a tool is designed by a tool designer, O.K.'d, and then a print

goes to the foreman of the tool department, who specifies the size

and gets the steel from the cutting-off department. After finishing

the machine work it goes to the hardening room, and this is the

problem we shall now take up in detail.