Electric Welding—Oxy-acetylene Gas Welding—The Fagot Weld—The
Separate Heat Weld—Scarfing—Upsetting—Making the Weld—Lap
Welding Without Scarfing—Jump Welding—Butt Weld—Split
Welding—Corner Weld—T Weld.
A rapid blast on the start, not only heats the outer part of the metal
first and not the center, but it also burns out the fire and makes it
become hollow before the metal has the welding heat. There is a right
and a wrong way of taking a welding heat from the fire to the anvil. The
pieces must be lifted clear up out of the fire, and must not be dragged
thru the dirt and cinders on the inner edge of the fire. Iron will not
unite when dirty. It is very easy to get a clean heat if one will pay
attention to having the fire clean. Do not attempt to get the welding
heat in a dirty fire; this is one thing that must be impressed upon the
mind of one working at the forge. The skillful worker in iron always pays
particular attention to the fire, for he knows by experience that it must
be clean, in order to do good work.
Welding is also done with an electric welding machine. The pieces to be
welded are clamped and held in bronze clamps. The clamps are adjusted so
that the ends of the pieces to be welded touch. They can be moved so as
to bring the pieces into close contact or separate them. When the pieces
are in close contact, the current is turned on. The pieces are then
separated a little so that the current jumps across the space between
them, forming an electric arc. This heats the ends to a welding heat,
and by forcing them together they are welded.
Another form of welding is by the oxy-acetylene gas method. It is
being used extensively at present, and has been found very valuable
and economical in making the lighter welds. It is possible to weld
steel, iron, cast-iron, copper, brass and aluminum by this process. The
apparatus consists of a specially designed blow pipe, an acetylene tank
and an oxygen tank under pressure.
The method of welding is to heat the pieces to be welded with the
blow pipe until they reach the fusion point. For instance, in welding
cast-iron, the pieces are clamped together, a V shape is cut nearly thru
the joint, the metal is heated to the fusion point, and a feeder, which
is a small cast-iron rod, is melted into it. In welding steel, the feeder
is a steel rod; for copper or brass welding, a rod of copper or brass is
used. Nowadays this method is extensively used in automobile work, in
repairing cracked cylinders.
[Illustration: Fig. 21.]
A very simple weld to make by heating in the forge, is what is known as
the fagot weld. In doing this, two or three pieces are welded by simply
laying one piece on top of the other, or a bundle of pieces of iron of
various sizes and shapes are bound together, heated and welded. For
example, if a bar of flat iron is heated and cut half thru in several
places, doubled over and over, one piece on top of the other and then
welded in order to make a large piece of stock this would be called a
fagot weld.
In Figure 21, the pieces are represented ready to make a fagot weld.
The welding of two pieces of stock by scarfing and lapping is known as
a separate-heat-weld, so called because the pieces are detached while
the heat is taken. In making any kind of a weld there is more or less
stock wasted in the raising of the welding heat, therefore the parts to
be lapped and welded are always upset or thickened and then scarfed.
The word “scarfed” means the shaping of the ends of the bars so that
when heated and lapped one on top of the other, they will fit and make a
splice, leaving the stock when hammered about its original size.
The method of upsetting is to heat the ends of the bar, then set the hot
end on the anvil with the bar vertical and hammer on the other end. This
thickens the heated end. If it is a long heavy bar, the worker churns
the bar up and down striking the hot end on the anvil. A bar may also be
heated on the end, then fastened in a vise and the hot part hammered to
thicken it. In upsetting, the bar must be kept straight as hammering will
bend it where heated; if not kept straight, it will not thicken.
[Illustration: Fig. 22. Fig. 23.]
When a piece is upset about one inch in diameter for a three-quarter
inch, round bar, it is scarfed by setting the hot end on and near the
outer edge of the anvil. It is then driven back on a bevel by hammering.
See Figure 22. It is also turned on the side and beveled on both sides to
nearly a point. See Figure 23. The scarf must not be hammered when the
piece is held in the center of the anvil, (Figure 24), for the reason
that the edge of the hammer comes in contact with the anvil, pecking
dents in it or breaking out pieces from the hammer.
[Illustration: Fig. 24. Fig. 25.]
Another method of scarfing is to hammer the end partly back as previously
explained, then set the piece on the inner edge of the anvil and hammer
it as shown in Figure 25. After each blow, it is drawn away from the edge
of the anvil just a little; this tapers it with a series of little steps,
not for the purpose of making notches in the scarfs to fit together and
hold while hammering, but simply because the edge of the anvil leaves it
in this condition when tapered. It is also drawn pointed by hammering on
the outer edge of the anvil.
Theory teaches that the scarf should be made with the beveled part
convexed. However, in practice, it is made to look like the drawing in
Figure 26. Note the raised parts at “D”. This is forced up when the scarf
is first driven back with the hammer as shown at “B”.
The reason that the high part should be on the scarf, is, that when
lapped it gives an additional amount of stock at this part of the laps
to be hammered. If the scarfs are made flat, when hammered, they are
not liable to finish up without having the pieces thin, or the point of
the lap exposed. If the scarfs are made concave, it is claimed by some
workers of iron that dirt will deposit there and result in a poor weld.
This is true to some extent. However, dirt will deposit on any scarf
unless the fire is clear. With a concaved scarf when lapped, there is
not stock enough to be hammered without leaving the pieces thin, or the
lapping too long when welded. Scarfs should not be made concave.
[Illustration: Fig. 26.]
[Illustration: Fig. 27. Fig. 28.]
Notice in Figure 27, the incorrect way of scarfing and in Figure 28, the
correct way.
The scarfs must not be made too long; this is a common fault with all
beginners and one to avoid. The scarfs should be made a little longer
than the thickness of the iron, perhaps 1½ times the thickness.
In raising the welding heat, the pieces must be placed in the fire with
the scarfs, or beveled part, down. The fire must be a clean one. A well
burned fire is best. A new fire is not a good one to raise the welding
heat in, as there is too much smoke and green coal that comes in contact
with the metal. The hammer should be placed on the anvil about over the
square hole, so it will be handy to reach when making the weld. The anvil
should also be clean. A heavy hammer should be used in welding. The
proper way to hold the hand hammer is with the fingers around the handle
and the thumb protruding along the side and near the top. The thumb
should never grip around the handle, but lie along the side to guide and
direct the blows. When using the sledge hammer, stand in front of the
anvil and not at its side, and let the first blow be a light one.
In heating a slow blast is maintained. When the pieces begin to get about
yellow, more blast is used. The pieces can be watched without removing
them from the fire. They should be turned over occasionally, moving them
nearer to the surface of fire to see how the heat is progressing, and
then under the coke again. Care must be taken to get both pieces heated
alike. If one piece should get hotter than the other, it can be moved
over in the fire a little, and the cool one put in its place. Perhaps
the fire is hotter in one spot than another. If one piece is heating
much faster than the other, lift it clear up and out of the fire for a
few seconds to cool and give the other piece a chance to become hotter.
If the points of the scarf are heating too fast for the body, the pieces
must be pushed thru the fire a little farther.
It is a good plan sometimes, when the pieces are about a yellow heat
to shut off the wind for a moment, to let the pieces and fire even up
and give the heat a chance to soak thru them. As the pieces become
nearly white, the blast is increased. Welding heat is about 1900°-2000°
Fahrenheit, and can only be determined by experience. When the
temperature of the pieces reaches the welding heat, they are lifted up
and out of the fire and taken by the smith to the anvil, without the aid
of a helper. The smith raps them against one another or against the anvil
to dislodge any dirt that may be on the scarfs. The piece in the left
hand is set against the inner edge of the anvil. The piece in the right
hand is now moved across the anvil until it comes under the top one. See
Figure 29. The piece in the left hand is then placed on the under one, by
simply raising the hand, teetering the piece on the edge of the anvil,
and holding it firmly by pressing down. This is important. The smith lets
go of the piece in his right hand, and taking the hammer strikes lightly
until the two are stuck, after which he welds them together with solid
blows, first on one side, then on the other and finally on the corners.
[Illustration: Fig. 29.]
It requires some practice to be able to take two pieces from the fire
and place them in position on the anvil to be welded. This should be
practiced by the pupil under the eye of the teacher, perhaps a dozen or
more times, with the cold pieces before he undertakes to get the welding
heat. If one cannot take the pieces out and place them in position, he
cannot make a weld of this kind.
Two boys should not be allowed to work together on this weld. One can do
it much better than two. It is a one-man job. There is nothing difficult
about it, after the method is learned by deliberate and persistent
practice with the cold iron. There is no need of hurrying when taking the
pieces out of the fire to the anvil.
If the scarfs are too long, they will overlap one another too far and
cannot be welded down quickly enough. If too short, they hammer down too
quickly to make a good job, and the weld will be thin.
If the scarfs are the right length and about the same size, which is
important, the weld will finish down in good shape and make a smooth job,
providing the ends are clean. When the pieces being heated, look as tho
they are covered with grease, you may be sure the fire is dirty, or is
too new.
_Lap Welding Without Scarfing._
A lap weld is sometimes made without scarfing the ends. For instance,
pieces of 1″ × ¼″ iron are to be welded by the lap method. They are
brought to a welding heat without upsetting; taken to the anvil as
previously explained for the scarf weld, lapped about ⁵⁄₁₆-inch, as shown
in Figure 30, and welded. This form of welding is used in a hurry-up job
where there is no great amount of strain on the work. It is impossible
to make a strong weld this way. Very thin stock, either iron or steel,
can be welded to advantage in this manner by hammering on the flat sides.
The edges, instead of being hammered, are cut off with a chisel, then
ground or filed smooth. In welding very thin stock, a little flux is
used. Always weld by separate heats, and do not rivet or split the stock
to hold both ends in place. This is not necessary. Try to make the weld
with one heat. All good welds are made in one heat.
[Illustration: Fig. 30.]
_Jump Welding._
[Illustration: Fig. 31. Fig. 32.]
For example, a piece like the one shown in Figure 31, is to be made by
welding. The pieces should be prepared as shown in Figure 32. The square
piece is 1″ by 1″ by 6″, the flat one 1½″ by ½″ by 8″. The square piece
is heated directly on one end. If the heat cannot be taken short enough,
it may be cooled in water so as to upset it with a lip or projection, as
shown. This lip can be worked out afterwards with a fuller, or it may be
driven into a heading tool which has the top corners of the hole rounded.
This will leave the corners of the lip round as shown. The bar at the end
should also be made slightly convex, so that the center part comes in
contact with the flat piece first. The flat piece is also upset in the
center.
In welding, separate heats are taken. With the square bar, handled with
the right hand, the pieces are brought to the anvil by the smith. The
square bar is set on top of the flat one, and a helper strikes the top
piece with the sledge, driving it down into the bottom one. The edge of
the lip is then welded fast with a hand-hammer; or a fuller or set hammer
is used, the helper striking with a sledge.
_Butt Weld._
[Illustration: Fig. 33.]
Iron may be welded by butting the ends together. In doing this, the
bars must be long enough so that they can be handled without tongs. For
instance, two bars of one-inch round stock, one five feet long and the
other shorter are to be welded. This size is about as light as can be
welded with this method. The ends are heated and upset a little making
them a little high in the center so that when they are placed together,
the contact is in the center. A short heat is taken on the end of each
bar. The smith takes out the long bar and the helper the short one,
butting the ends together on the anvil, as shown in Figure 33. The helper
hammers on the end of the short piece with a heavy hammer while the smith
holds the long one firmly, and hammers on the joint, at the same time
turning the bar so as to hammer the joint all around. In welding heavier
stock, a sledge should be used requiring more helpers. This method makes
a good weld, providing the heats are clean.
_Split Welding._
Figure 34 shows a drawing of round stock prepared for a split weld. In
making this weld, one piece is heated on the end, caught in a vise and
split with a thin chisel. See Figure 35.
These prongs are then spread and scarfed on the inside with the ball of
the hammer letting them become fan shape and as wide as possible. See
Figure 36. The other piece is upset and both pieces are caught in the
vise. The scarf is then hammered tight and the ends are cut so as not to
have them too long. See Figure 37. The cutting of the scarf, and partly
into the bar, helps to bind the pieces firmly while the heat is being
taken. See drawing of piece ready to be welded, Figure 38.
[Illustration: Fig. 34. Fig. 35.
Fig. 36. Fig. 37.
Fig. 38. Fig. 39. Fig. 40.]
A heat is now taken, using a little sand or welding flux, if the stock
is very small. In welding, the first blow is struck on the end of the
split piece to drive it down tight and weld it in the center. See Figure
39. The sides are next hammered to weld the laps. It is then finished.
On heavy work, the heats are taken separately and placed on the anvil by
the smith, in the same manner as described for a jump weld. Another form
of split welding is shown in Figure 40. This method is used in welding
heavy iron and steel, such as picks and drills. Notice the little beards
cut with a chisel to help hold the pieces in position when heating. Heavy
tool steel is also welded with this form of splitting. The first blow
struck with the hammer on this weld, is on the end, forcing the pieces
together; then on the flat part.
_Corner Weld._
In Figure 41 is shown an angle made by welding on the corner; this is
called a corner weld. It is generally made by using square or flat stock.
Figure 42 shows the scarfs prepared for a corner weld, using 1″ by ½″
stock. The piece at “A” is scarfed with the ball of the hammer. The one
at B, with the face of the hammer. Separate heats are taken and the
pieces lapped and welded.
[Illustration: Fig. 41. Fig. 42.]
_T-Weld._
The scarfs for T-welds are made in just the same manner as for the corner
weld, excepting that one scarf is in the center of the bar. See Figure 43.
In taking the pieces from the fire to the anvil, the one scarfed in the
center is handled with the tongs in the left hand. The one scarfed on
the end is handled with the right hand, letting it under the other, and
then hammered. Notice how wide the scarf is made on the end piece at “A”.
This is done to cover the other scarf. All flat “T” scarfs are made in
this manner.
[Illustration: Fig. 43.]