Lathe And Planer Tools

: The Working Of Steel

FORGING.--Gently warm the steel to remove any chill, is particularly

desirable in the winter, then heat slowly and carefully to a scaling

heat, that is a lemon heat (1,800 to 2,000 deg.F.), and forge uniformly.

Reheat the tool for further forging directly the steel begins to

stiffen under the hammer. Under no circumstances forge the steel

when the temperature falls below a dark lemon to an orange color

about 1,700 deg.
. Reheat as often as is necessary to finish forging

the tool to shape. Allow the tool to cool after forging by burying

the tool in dry ashes or lime. Do not place on the damp ground

or in a draught of air.

The heating for forging should be done preferably in a pipe or

muffle furnace but if this is not convenient use a good clean fire

with plenty of fuel between the blast pipe and the tool. Never

allow the tool to soak after the desired forging heat has been

reached. Do not heat the tool further back than is necessary to

shape the tool, but give the tool sufficient heat. See that the

back of the tool is flatly dressed to provide proper support under

the nose of the tool.

HARDENING HIGH-SPEED STEEL.--Slowly reheat the cutting edge of

the tool to a cherry red, 1,400 deg.F., then force the blast so as

to raise the temperature quickly to a full white heat, 2,200 to

2,250 deg.F., that is, until the tool starts to sweat at the cutting

face. Cool the point of the tool in a dry air blast or preferably

in oil, further cool in oil keeping the tool moving until the tool

has become black hot.

To remove hardening strains reheat the tool to from 500 to 1,100 deg.F.

Cool in oil or atmosphere. This second heat treatment adds to the

toughness of the tool and therefore to its life.

GRINDING TOOLS.--Grind tools to remove all scale. Use a quick-cutting,

dry, abrasive wheel. If using a wet wheel, be sure to use plenty

of water. Do not under any circumstances force the tool against

the wheel so as to draw the color, as this is likely to set up

checks on the surface of the tool to its detriment.