hour. If a motor generator set with a seventy volt constant potential
machine is used for a welder, the cost will be as follows:

Metallic electrode 25.2c. Carbon electrode 84c per hour. With a machine
which will deliver the required voltage at the arc and eliminate all the
resistance in series with the arc, the cost will be as follows: Metallic
electrode 7.2c 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]