Part 9

You know now all the tools needed to equip a shop. I want to tell you about the fuels, such as coal and charcoal, which you will use, and something about pig iron and wrought iron which I think you ought to know.

The smoke is the most troublesome thing in a blacksmith's shop. The old-fashioned forge is perhaps the best made to draw the gases and smoke out, except when exhaust fans are used for that purpose. Hoods are fitted to pull down over the fire, completely covering the smoke area, and the suction made by the fan will draw all the smoke from the fire. This, of course, is possible only in modern equipped shops. The portable forges that we use have none of this drawing-out system, except through a natural draft chimney, made either of bricks or by extending an iron pipe from the hood through the side of the shed or through the roof. The down-draft system is a hood placed to one side of the fire. It falls over the fire by means of a hinge placed on the hood. This is not as effective as the overhead system on account of the smallness of the hood. The pipes are all underground, otherwise the system is the same as the overhead system.

_Danger of explosion:_ Coal gases leak into the tuyere when the blast is shut off. When the blast is put on these gases are blown up into the hot fire and they explode from the heat. They do no harm, except the noise made by the explosion.

_Fuels:_ The coal used in a blacksmiths' shop is a soft coal called bituminous coal. It is supposed to have less phosphorus and sulphur than any other kind of coal. Coal containing either of these ingredients should not be used. Sulphur makes iron hot short and phosphorus makes the iron cold short that is, the iron is made brittle while hot by means of the sulphur, and brittle when cold through the effect of the phosphorus. When this soft coal is heated the coal tar is burned out and the coal burns into a coke.

_Charcoal:_ Charcoal is a solid fuel and the very best fuel for heating purposes. It is free from the impurities mentioned here. It is made by burning hard wood in a closed oven or kiln. This kiln in turn burns the wood into lumps of charcoal. The cost makes the only real objection to the use of charcoal as fuel.

PIG IRON

Iron ore is an oxide of iron containing from 35 per cent. to 65 per cent. iron. The rest is oxygen, phosphorus, sulphur, silica, and other impurities. Iron ore is charged into a blast furnace, mixed with limestone as a flux, and melted down, with coke as fuel. The metal which results from this melting is known as commercial pig iron.

WROUGHT IRON

Wrought iron is made from pig iron. The pig iron is remelted in a so-called puddling furnace by charging about half a ton at one time into the furnace. While in a molten state it is stirred up with large iron hooks by the puddler. It is kept boiling so as to expose every part of the iron bath to the action of the flame in order to burn out the carbon. The other impurities will separate from the iron and run out of the furnace as slag.

The temperature in the puddling furnace is high enough to melt pig iron but not high enough to keep wrought iron in a liquid state. So, as soon as the small particles of iron become purified the partially congealed portion forms a spongy mass, in which small globules of iron ore are in a semi-plastic state. These are gathered up by the puddler and his helper and are formed into a ball on the bottom of the furnace by means of long rabble bars used for this purpose. The ball is about 150 to 200 pounds in weight. These lumps of iron are taken to a large hammer or squeezer.

There they are shaped into long blooms to fit the rolls. They are taken right from the squeezer to the rolling mill and rolled out into bars 4 ins. or 5 ins. wide and 3/4 in. thick. These bars are called muck bars owing to their spongy-like appearance and the large quantity of cinders which they contain. The muck bars are now cut into lengths of 3 ft. and 4 ft. and are piled on top of each other in blocks of 200 lbs. The blocks are put into a heating furnace and heated to a welding heat. While at this heat they are put through the rolls, thus welding the whole mass together, at the same time reducing the pile to sizes required by the market. When cold these are cut into lengths for use. This is the iron used in most blacksmiths' shops.

XXI

FIRST PROBLEMS IN FORGING

HOW TO MAKE A STAKE PIN

Stake pins are used for holding ropes in place, such as those on tents, etc.

_Material:_ 1/2 in. round × 18 ins. long of wrought iron.

_Tool:_ Hand hammer.

_Directions:_ This sketch is made full size and it shows a round stake pin with a four-sided tapering end about 3 ins. long. Place one end of the bar of iron into the fire. It should be placed so that the iron will be parallel to the bottom of the hearth.

All the heating done for this kind of work must be done in a reducing fire. There are two kinds of fires, the oxidizing fire and the reducing fire. The oxidizing fire is one where the quantity of air blown in is not all consumed by the fire. There is an excess of air and an oxide is formed on the iron. This prevents it from heating sufficiently. The reducing fire is one where the blast is in proportion to the consuming power of the fire--that is, just enough air is blown in to be used up by the fire.

The greater the temperature the more coal and likewise the more blast required. So that a temperature of 2500° Fahrenheit can be easily gotten on an ordinary forge fire. While the iron is heating it should be drawn out of the forge fire once in a while to be examined. When it has reached a white heat, not sparkling, place it on the anvil, and with a hand hammer begin at the end and drive it into shape according to your sketch. Hammer this until the iron begins to darken. Place it again in the fire and repeat as before until the thing is finished. A piece of iron may be heated a dozen times while working it into shape. All depends upon the skill and experience of the worker.

You will probably learn in this problem that metal will burn in this high temperature the same as a piece of wood and very much quicker. It does not smoulder like wood; it just melts away. It would be well to have the point of the iron stake melt or burn off in this particular case so that you can learn all about the heating, melting, and burning of iron. The fine point on the stake is made by keeping the metal on the extreme outer edge of the anvil, so that the outer half of the hammer face will project over the anvil edge, thus reducing any metal between the two into a very small space. (See position of hand hammer in the article on tools.)

When the work is finished the temperature of the metal should be low. This prevents the metal from scaling and gives an opportunity for a smooth finished surface.

Staples are small U-shaped pieces of iron with pointed ends. They are driven into wood for the purpose of holding some attachment in place. We have staples for barn doors, to catch the gate hook, to fasten chains, etc.

_Material:_ One piece of 1/4-in. round iron 4-1/2 ins. long.

_Directions:_ Heat one end of the iron piece. Draw it to a square point as was done on the staple pin. Flatten this point as shown in the drawing. Cut it off square at the extreme end so that it will be quite sharp when finished. Repeat on the other end. The piece will now be about 6-1/4 ins. long, about 1/4 in. round in the middle, with square, tapering points. The centre is now heated and the piece is bent over the horn of the anvil to the shape shown in the drawing.

In bending this over the horn of the anvil strike with light blows so that the two ends will be the same length. If it is warped or twisted, flatten it out again on the anvil till the flat sides lie in the same plane.

GATE HOOK

This hook is used for fastening doors as well as gates. The drawing shows a gate hook twisted in the middle. _Material:_ One piece of 5/16-in. square iron about 6-1/4 ins. long.

_Directions:_ Mark off with the centre punch 1-1/8 ins. on one end and 1-5/8 ins. on the other. Put the short end into the fire and draw it out until it is 1/4 in. square. Hammer the corners down, thus rounding the end until it measures 1/4 in. in diameter and is about 2-1/8 ins. long.

Repeat on the large end and draw this out until it measures 2-3/4 ins. long. Bend the end as shown by the drawing. When both ends are bent in shape put the piece into the fire and heat it red hot between the eye and the hook. Place it in the jaws of the vise about 1 in. from the eye, and with a pair of tongs and a wrench grasp the piece about 1 in. from the hook and give it one complete turn. This twists the hook in the centre like the drawing. If it has become bent while twisting it may be straightened by hammering it between two blocks of hard wood. This prevents bruising the sharp edges of the twist.

These large hooks are most useful around a stable and are used to hold harness, bags, etc.; in short, they are general utility hooks. They are simply and quickly made.

_Material:_ Stock 3/8 × 6 ins. long round iron.

_Directions:_ Flatten the iron down by heating it red hot. With the hand hammer flatten out one end 4 ins. long, 1/2 in. wide × 1/8 in. thick. One inch from the shoulder made by the flattening begin to draw out the end to a round straight taper, 3-1/4 ins. long. Bend the flat part over the flat end of the anvil, to fit a joint or any wooden beam (as shown by the sketch), and hook it over the horn.

This hook may be made any size according to the purpose for which it is to be used.

TWO-PRONGED FORK

This two-pronged fork is found useful for pitching hay, fishing, etc.

_Stock:_ 3/4 × 1 × 5 ins. long, soft steel.

_Directions:_ Two inches back from the end of the bar punch a small hole in the middle of the iron. (See method of punching). Split the piece with the chisel up to this hole. Open the part split and spread at right angles to the shank. Heat the piece up at the crotch. With a fuller, fuller down to 1/2 in. back of the spread arms. Draw the stem out 1/2 in. round. Now the fork is blocked out ready for finishing. This is done by following the drawings for the dimensions and size. Notice that the two ends of the fork are drawn out to a sharp round taper. The stem is drawn out to a sharp square taper, which is to be driven into a wood handle.

_Fish spear:_ If this two-pronged fork is meant for a fish spear, used so often in rivers where the current is very swift, the extreme ends are flattened down to a spear point as shown in the drawing.

BOLTS

A bolt consists of a stem and a head. Bolt heads are of all shapes--square, hexagonal, round, flat, etc.--while the stem is always round. As a rule, the thickness of the head equals the thickness of the stem, and the diameter of the head is about 1-1/2 times the thickness of the stem. This proportion is generally kept for square and hexagonal bolts.

_Directions:_ Out of the piece of iron used enough of the end is upset to make the head. To do this, heat 2-1/2 ins. from the end of the bar to a bright red heat. Take the piece out of the fire, place the hot end on the anvil, and with the bar in a vertical position hammer upon the cold end. The cold end is driven into the hot end, thus shortening or upsetting the bar. This is repeated. The end is heated again and the hammering is continued until the enlarged end has the right proportion for the head of the bolt. (See drawing.) Heat the enlarged end again and pass the cold end of the stem through the heading tool. Place the heading tool upon the anvil in such a position that the stem passes through the hole in the anvil. The upset end is hammered down against the heading tool until the head is the required thickness. Take it off the heading tool and square it up with the hand hammer. If, after squaring up, the head is found to be too small in diameter and too thick, it is again put into the heading tool and hammered down. This is repeated until the head is finished according to the drawing shown.

All hand-made bolts are made on this principle, whether they are very large or very small.

If a six-sided bolt is desired the same method is used. The head is made six-sided instead of being squared as was done in the first case. The bolt is finally cut to the required length and the end is bevelled off ready for threading. Bolts may be made without going through the process of upsetting the stock. In that case the bars used are of any diameter, depending upon the size of the stem needed. Bend a piece of iron for a collar to give you the amount of stock required for the bolt head. Heat the end of the iron bar. Put this hot end into the collar. Upset it so that it fills the space in the collar. Put it into the fire, then weld and finish as you did in making the head with the end upset.

All bolts that are on the market except special bolts are made by bolt heading machines. Up to 3/8 in. in diameter all bolts are made without the use of heat. Those above that size are all heated red hot and the principle is exactly the same as you used when you made the bolt by hand. The machine upsets the head and at the same time shapes it into any desired shape.

NUTS

Nuts are used in conjunction with bolts for fastening things together or tightening up parts of machines. There are two ways of making nuts; one is to cut a piece of metal off the right length, punch a hole in the middle, and finish it by shaping it on the end of a mandrel or punch. The second way is to weld a collar and shape this on a mandrel. Though the second method involves welding and is the more difficult of the two, it is the better method. However, the grain of the metal in the second method runs around the nut, while in the former case it runs lengthwise. For this reason the nut is apt to split when tightened up too tight on the bolt. The method explained here is the easier one of the two: it is the simple process of making the nut by punching the hole.

_Material:_ Stock 1 × 5/8 in. of wrought iron, any length.

_Tools:_ Hammer, punch, hot chisel, pair of calipers.

_Directions:_ The drawing here shows each step in the process of making the square nut. Measure off 1-1/16 in. on the bar and with the hot chisel nick on each side almost through. Find the centre of the piece and, with the punch, punch a hole through it after heating it red hot. Place it on the anvil. Place the punch in the centre and drive down from one side until the impression of the punch shows through on the other side. Withdraw the punch and turn the piece upside down. Place the punch upon the impression shown through, driving down till the centre piece is loosened. It is now put over the hole of the anvil and this loosened centre piece driven out. This leaves a hole in the hot iron. All holes made in hot iron are punched through in this way whether they be large or small. The size of the hole is determined by the size of the punch.

Re-heat the iron, push the punch into the hole made, and by a bending motion break the piece off where it is nicked. The piece now is sticking on to the end of the punch. Place them on the anvil and square up the nut while the punch is still in the hole. This prevents the hole from changing its shape while the nut is being driven into shape. It is now taken off the punch and flattened down to the desired thickness. Repeat this edging up and flattening down till the nut is finished.

Hexagonal nuts are made in the same way, except for the squaring up. When the piece is ready for shaping it is made round while on the punch and then made six-sided. It is flattened and edged up in the same manner until the desired size is reached.

XXII

WELDING

It is often necessary to join together two pieces of iron, or the ends of the same piece, as in forming a circle, so that the joint will form one solid mass. When this is done the pieces are said to be welded together. Most of the problems treated so far have had to do with single pieces of iron. Often many pieces are welded together to make one forging, as in making the horseshoe. This is called built up work.

It is possible to weld any iron surfaces provided no oxide of iron is formed upon the surface. If such a coating occurs welding is impossible. Iron heated in the air absorbs oxygen, which results in the oxide formation. There are two ways of guarding against this difficulty: (1) Suitable fluxes, and (2) reducing fires.

The best flux is a sharp sand, usually beach sand. This is sprinkled over the ends to be welded. The sand fuses on to the ends of the iron and excludes the air. The reducing fire is one that consumes all the oxygen that is forced into it by the blast. This is obtained by having a thick bed of fire for the air to pass through before coming into contact with the iron and by keeping the blast pressure low enough to enable the fire to burn all that is admitted. A thick fire, so to speak, should always be kept.

TO MAKE AN IRON RING

The simplest problem for a first weld is a flat iron ring. This drawing shows a ring 3 ins. in diameter on the inside and 5 ins. on the outside.

_Stock:_ Flat piece of iron 13-1/2 × 1 × 3/16 ins.

_Directions:_ The making of this ring involves the processes of bending and welding. Before the bending is done the two ends are upset and made about 1-1/16 in. thicker than they were, for about 1 in. back from either end. To do the upsetting, place the hot end on the anvil vertically and strike on the cold end with the hammer until the required thickness is obtained. If the end which is being upset was not heated more than 1-1/2 in., it will probably upset without bending. If heated more than this the probabilities are that it will bend during the process. If it does so, it should be laid upon the anvil and the bend hammered out. When the desired thickness has been obtained scarf the ends as shown in the drawing, using the round end or peen of the hammer to do so. (See scarfing.)

Do the same to the other end, putting the scarf on the opposite side to the first one. Now heat the piece, about half its length, quite hot. Place it upon the thickest part of the horn of the anvil, strike upon the end that projects beyond the anvil, and bend it into a ring. The scarfs, being opposite, will now fit and come together. (See drawing.) Bend over till the two edges lap. This gives plenty of material where the joint comes, to allow for the waste of the material from the high welding heat and also that needed for the hammering of the metal during the welding. The upsetting is done to allow for this waste, and to give opportunity to reduce the pieces to the required thickness. All welds should be a trifle large at the joint. The driving down edgewise on the horn of the anvil bends the material, but prevents one shaping it to its proper dimensions. That is why in flattening down the weld care must be taken not to widen the iron at that place so that it is too thin. A few trials will make this perfectly clear. A finish on the iron depends upon how skilfully one can use the hammer without unduly marking the metal.

SMALL CHAIN

Most chains are made by hand, especially those used for the purpose of lifting heavy loads. Small chains, where no special strain is called for, are welded by electricity. There are special factories for the making of chains. Most of these factories have rolling mills attached. The material is here rolled out to suit the different size chains that are made. Machinery forms the bars of iron into special shapes the size of the links. These in turn are cut by machinery. These links are all of the same size and are cut off on an angle, thus making the scarf. They are taken by the workmen, the ends lapped over slightly, then put into the fire and welded. Within the last few years the Navy Department has taken up the method of welding the large anchor chains by machinery.

_Stock:_ 3/8 in. round, 6 ins. long.

_Directions:_ The drawing shows the size of each link in this chain. Heat the 6-in. piece in the middle. Place it on the horn of the anvil and bend it U-shaped, as you did the piece for the staple. (See articles in welding for chains.) The two ends are the same length. This is perhaps the only weld that is made without upsetting. When the scarfs are made like the drawing, bend the ends so that the scarfs overlap. Now it is ready for welding. Place the link in the fire. Be careful to have the link well covered both above and below with hot coals. Let there be just enough blast to increase the heat of the fire. In a little while the sparks will flow up from the iron. At this time the link should be turned upside down in the fire without changing its position. The hottest part of the fire being underneath, the iron will heat there quickest. This turning it upside down finally brings all the parts to be welded in the hottest part of the fire. When these iron sparks begin to show, it is time to take the piece out. Place it on the anvil and lightly tap upon the joint. The iron is very soft on account of the intense heat and if the blows are too heavy the iron will flatten out until it is too thin. In that case it would be impossible to finish the piece and make the weld the size it should be when done. If you examine the links of any chain you will have difficulty to find the welded end. The process of welding is not easy at first, but a few trials with the heating of the iron and handling the tools at the critical moment will prove encouraging. Chains are usually made by making first one link, then putting the stock for the next link into the first, before bending the second end.

All hooks, swivels, or shackles are put on the chain when made, in the same way that you add a link in order to lengthen the chain.

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.

_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.