[Illustration: Axle Welding]
[Illustration: Flatten the ends out; split and push together]
[Illustration: Ring Welding]
Welds are named according to the manner in which the pieces are put
together. The principal welds are: (1) flat welds, (2) butt welds, (3)
lap welds, (4) cleft welds, and (5) jump welds. The selection of the
kind of weld to be used in any problem depends upon the form of the
pieces of metal to be worked upon.
[Illustration: Hammer peen]
_Flat welds:_ For flat welds the ends of the pieces of metal are first
upset. Use the peen of the hammer and draw the metal out thin at the
end, flatten it out and narrow it up edgewise at the extreme end. The
metal is forced first forward and backward by the hammer strokes.
Large scarfs are sometimes made by using a fuller. This is a very
much quicker way for large work than the one just explained, but one
requires a helper to handle the sledge hammer in this case, to strike
down on the fuller.
[Illustration: Use of fuller in making scarfs]
[Illustration: Scarfing on edge of anvil]
Most smiths use the edge of the anvil for making scarfs. Place the edge
of the metal, after it has been upset, on the edge of the anvil and
strike down on the top with a hammer or sledge. This moves the metal
with each blow and the end of the bar is increased, making, as it were,
a series of steps. It is a process much the same as fullering except
in place of the fuller you use the edge of the anvil. This is the
quickest way to make a scarf, and the weld depends wholly upon how the
scarfs are made in any one of the operations spoken of here.
If the scarf is well made it will be a little higher in the middle than
at the sides, so that when the pieces are placed together the slag
that forms will squeeze out. The welding is done as follows: Place the
scarfs of both pieces separately in the fire, the scarfs downward.
(When we speak of scarfs we refer to the bevelled edge of the roughest
part of the scarf.) This prevents any impurities melting on the scarf
surface. When the scarf begins to get hot enough to weld, iron sparks
will blow out with the blaze. This is the sign to get things in
readiness. One cannot linger for a moment when the iron is hot enough
to weld. See that the anvil is clean. Have the hammer ready in hand. If
one has a helper he will handle one piece while the smith handles the
hammer and the other piece.
If there is no helper a hammer is placed conveniently near the anvil.
The two pieces of iron are grasped by the smith, one in either hand,
drawn out of the fire and given a sharp rap on the edge of the anvil or
forge to remove any dirt or pieces of coal clinging to the scarfs. One
piece is placed on the anvil and the other piece is put on top of this.
The weight of the second piece holds the first piece in place until
such time as the smith can get his hammer ready to strike. As soon as
the pieces stick together the ends of the scarfs are welded first. They
are the thinnest and will cool the quickest. The body of the piece
welds while you are welding the scarfs. Both sides are worked upon,
first on one and then on the other, till the piece is hammered down to
the required size. In trial work it is best for one to use pieces of
iron long enough to avoid the use of tongs.
[Illustration: Butt welds]
_Butt welds:_ If the butt weld is carefully made it is perhaps the
safest weld of all. This method is used mostly in welding round iron
bars, 1-1/2 ins. in diameter up to 2-1/2 ins. They are made as follows:
the ends of two bars are heated to a welding heat. Then they are
brought out of the fire, put in a swage, end to end, and struck on the
ends with a sledge hammer. While driving upon the ends the iron upsets
when the contact takes place and at the same time the smith is driving
the weld down. Two processes are acting here, one lengthwise and one
downward. This makes the best weld, from the fact that the two ends
that come together have a welding heat on the whole surface of each, a
condition hard to get in any other kind of weld.
[Illustration: Flat Scarf]
_Lap weld:_ Two flat pieces are laid face to face, as shown in picture,
and are welded. One must be careful that the two pieces have the same
temperature, otherwise the colder piece would cut into the hotter and
make a defect.
[Illustration: Split scarf, cleft weld]
_Cleft weld:_ If the weld is required to stand much strain, such as in
parts of a locomotive frame, pieces are generally joined by the cleft
weld. One piece is upset and split with a chisel. The two sides are
spread apart. The other piece is scarfed on both edges to fit into this
opening. If the pieces are very large much of the welding can be done
while in the fire. The two pieces are placed together, in the proper
position, in the fire. When the heat is hot enough to weld they are
driven endwise. This drives the point of the one piece into the crotch
of the other. Take them out of the fire and place upon an anvil or
under a hammer. Small pieces are welded in the same way, except they
may be driven with a hand hammer on the end just before driving upon
the surface. The piece is reduced to the proper size and finished.
[Illustration]
_Jump weld:_ When one piece of metal is to be welded at right angles to
another piece, a jump weld is made. Many are made by using a bob punch,
making a hollow depression in a flat piece, and a rounded or button
head shape on the end of the upright. Heat the end of the upright and
also the flat piece around the bob punch hole to a welding heat. Take
them out of the fire and drive the button head down into the hole made
by the bob punch.
[Illustration: Jump weld]
[Illustration: Corner plate]
Another jump weld can be made in the following way: when square iron is
to be welded to square iron, one end is upset and flattened. The other
end is simply upset a little when the upright is to be welded to it.
These ends are brought to a welding heat, and the work is finished as
in the first jump weld. The hammer plays an important part in these
jump welds, for the scarf projecting at the base must be welded by the
hand hammer.