ends are in plain sight of the operator at all times and it can easily be
seen when the metal reaches the welding heat and begins to soften (Figure
46). It is at this point that the pressure must be applied with the lever
and the ends forced together in the weld.

[Illustration: Figure 46.--Butt Welder]

The parts are placed in the clamping jaws (Figure 47) with 1/8 to 1/2 inch
of metal extending beyond the jaw. The ends of the metal touch each other
and the current is turned on by means of a switch. To raise the ends to the
proper heat requires from 3 seconds for 1/4-inch rods to 35 seconds for a
1-1/2-inch bar.

This method is applicable to metals having practically the same area of
metal to be brought into contact on each end. When such parts are forced
together a slight projection will be left in the form of a fin or an
enlarged portion called an upset. The degree of heat required for any work
is found by moving the handle of the regulator one way or the other while
testing several parts. When this setting is right the work can continue as
long as the same sizes are being handled.

[Illustration: Figure 47.--Clamping Dies of a Butt Welder]

Copper, brass, tool steel and all other metals that are harmed by high
temperatures must be heated quickly and pressed together with sufficient
force to force all burned metal from the weld.

In case it is desired to make a weld in the form of a capital letter T, it
is necessary to heat the part corresponding to the top bar of the T to a
bright red, then bring the lower bar to the pre-heated one and again turn