2c per hour; carbon electrode 42c per hour. This is with the
understanding that the arc is held constant and continuously at its full
value. This, however, is practically impossible and the actual load factor
is approximately fifty per cent, which would mean that operating a welder
as it is usually operated, this result will be reduced to one-half of that
stated in all cases.
CHAPTER VII
HAND FORGING AND WELDING
Smithing, or blacksmithing, is the process of working heated iron, steel or
other metals by forging, bending or welding them.
_The Forge._--The metal is heated in a forge consisting of a shallow
pan for holding the fire, in the center of which is an opening from below
through which air is forced to make a hot fire.
[Illustration: Figure 48.--Tuyere Construction on a Forge]
Air is forced through this hole, called a "tuyere" (Figure 48) by means of
a hand bellows, a rotary fan operated with crank or lever, or with a fan
driven from an electric motor. The harder the air is driven into the fire
above the tuyere the more oxygen is furnished and the hotter the fire
becomes.
Directly below the tuyere is an opening through which the ashes that drop
from the fire may be cleaned out.
_The Fire._--The fire is made by placing a small piece of waste soaked
in oil, kerosene or gasoline, over the tuyere, lighting the waste, then
starting the fan or blower slowly. Gradually cover the waste, while it is
burning brightly, with a layer of soft coal.
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