The Blacksmith’s Shop
XX — Blacksmithing and Tools
Let’s go to the blacksmith’s shop and tell the blacksmith what we have done. You see I’ve shown you all he taught me about copper, brass, and silver. I promised to take you there when we got through. Come on. Here we are! This is his shop. Mr. Blacksmith, this is my friend. I’ve shown him how to do work in metal and he can do all that you taught me. We both want to learn how to make things out of steel and iron. Are you ready to take us on?
Yes, boys, you are just in time to help me out. And while you are lending a hand I can show you how to make many things that every boy can learn to do with iron and steel. Come into the shop. First I’ll tell you about the blacksmith shop equipment. This is my forge and bellows, with the coal heap at the side; here is the anvil and here are my tools. You see it doesn’t take a blacksmith long to name the things he needs to equip his shop. But you must know how each thing is used and what it is used for. Let me draw you a picture of the forge on this board and explain to you how it is built.
A is the chimney. You see it has an opening in the bottom to let the smoke go up. B is a leather bellows. It is placed back of the chimney out of the way of sparks from the forge fire. The nozzle of the bellows goes through a hole ending on the hearth of the forge. C is the hearth where the coal is placed. D is a nest in the centre of the hearth, called a tuyere. Through this opening the blast from the bellows enters the coal heap.
The whole forge is built of brick and mortar. Modern forges are made of iron and steel and have a sheet iron hood in place of a brick chimney. But the principle of the tuyere, where the blast enters the forge, is the same as we blacksmiths have always used. Now I’ll build the fire in the forge. Here in this box are some shavings. I save all my shavings and put them here to start my fire with. Place the shavings over the tuyere and light them. Let them burn for a little while, then cover the whole with this soft bituminous coal. This kind of coal is free from sulphur and phosphorus, and it cokes very nicely when the gas and tar are burnt out. Now it’s time to use the bellows. You can take hold of this handle and pull down. The weights on the bottom pull the handle up again. Sometimes weights are placed on the top board. This helps to increase the air pressure. Notice that the bellows hang in a frame and the centre axis is fastened to the upright, allowing the upper and lower half to rise and fall. When the lower half falls it sucks the air in through a little trap door on the bottom, and when raised the trap door closes and the air is forced through the nozzle into the tuyere on the forge. This alternates, first taking the air in and then forcing the air out. Pump gently at first, then the coal will not smother the fire. That volume of smoke coming up is mostly from the burning shavings and it goes right up the flue. This blue flame that you see now shows that the gases are burning in the coal. When they are burnt out the coals give a red glow. Now the bright fire is shown through the coal. Put your poker into the coal heap and raise it gently. The opening made on the top is a vent for the heat to escape and prevents the fire blowing into the shop. An opening like this should always be left at the top, on account of the oxygen which is being pumped in constantly. Sprinkle a little water on the coal around the outside of the fire. This helps to pack the coal down tight and keep the fire in a confined space, for it is apt to spread and use up much more coal than is needed.
You see, boys, this is an old-fashioned blacksmith shop. Most of the work done here is horseshoeing, though we have many complex things brought in for us to repair, none of which can be turned away. All these shoes hanging on the rafters are for horses and mules. The mule’s shoe, you see, is a different shape from the horse’s shoe. I make these in my spare moments and we call them stock shoes. Notice that the stock shoes have no heels or toes on them. These are put on when the shoe is made to fit the horse’s foot.
Shoes are now made by machinery and I buy them when I haven’t time to make them. But they, too, must be fitted to the foot, for they come only in stock form.
Now I’m going to show you how to make a horseshoe. I’ll make it out of this piece of steel tire from a wagon wheel. We use all this kind of scrap to make the stock shoes. That’s why our made shoes can be sold cheaper than the manufactured shoes, if we have the time to make them. Steel is being used in place of iron in all branches of industry. A steel shoe weighing half a pound will wear as long as an iron shoe weighing one pound.
This piece of steel tire which I am using is 1 in. wide and 1⁄2 in. thick. I want to keep the thickness 1⁄2 in., but reduce the width to 3⁄4 in. To do this the end of the piece of metal is put into the forge fire. As soon as it is hot enough, I take it out and place it, edge up, on the anvil, and with the hand hammer draw it out any length I wish. You see that driving down on the edge of the hot bar thickens it. Now turn it over and drive on the flat side. You must keep driving first on the edge and then on the side until it is the right size. This is called stretching the metal out. Now the bar is long enough to bend in the shape of a letter U. Heat about 6 ins. of this bar and then place it on the largest part of the anvil horn. Strike on the projecting end with a hand hammer. It bends easily into the shape.
Take the chisel-shaped tool. The edge of this tool makes the groove to fit the nail heads. Every horseshoe has eight rectangular holes for nails, four on each side. These are punched through with this punch, and are made just large enough to fit the horseshoe nail heads. Now you see a stock shoe, and it is just like the dozens I have hanging on the rafters. But before the shoe is placed on the horse’s foot it must have the front piece, called the toe calk, welded on and the ends of the shoe turned up for heels. To make the toe calk I take a piece of iron or steel about 2 × 3⁄4 × 1⁄2 in. The end of this piece is prepared like this:
The little projection is made very sharp so that it can stick into the hot iron. In this way it is kept in place during the process of welding. When the calk is made I heat the shoe and place the calk in the proper position. The calk is cold and the little projecting point is easily driven into the hot iron. Now that it is held in place it must be welded on. Iron and steel are welded together only by the use of a flux. There are many kinds of fluxes used. For this I shall use borax. I buy it by the pound and it comes in boxes like this. Sprinkle a little on the calk, heat it in the fire, watch the fire. When the metal is hot enough to weld you will notice a brown smoke coming from the fire. That tells you the borax is burning. There, see the smoke! Now I must take the shoe out quickly and place it on the anvil. A few quick, light blows upon the calk and the welding is done! The hammering must be done quickly after the shoe has been taken out of the fire, or the cold air will lower the temperature and prevent the metal from uniting. There, it’s welded! Now I shape it and fit it to the horse’s foot. The heels can’t be bent up until I know just how long the horse’s foot is. I measure by placing it on the hoof. Then the two ends of the shoe are bent and driven down so that the height of the heels equals the height of the calk. Now, boys, this is a hand made shoe. When you know how to use the fire and the tools it is an easy problem to make a horseshoe.
So it is with all blacksmiths’ work. There is not anything about it you can’t do. Any boy can build his own blacksmith shop if he has a shed or shelter large enough to keep the rain from a forge, anvil, and some tools. You needn’t have the big, old-fashioned brick forge like mine. Here is a picture of a portable forge that I can recommend. It can be bought at almost any store that deals in hardware supplies. It is small and handy and can be easily taken from place to place. You can buy any size anvil you wish. They come in all sizes, weighing from five pounds to five hundred pounds. Here is a list of tools which will do all the work, both ornamental and plain, which you may wish to do. Get this equipment, then build your shop.
Blacksmiths’ Tools
Some of these tools you have used in your copper, brass, and silver work. You will need your vise, files, your various punches, dividers, hand cold chisel, and square. In addition, you should have the following:
Hand hammer: A hand hammer is used more than any other tool in the shop. The flat face is used for shaping material and the round plain for riveting, etc. The top and bottom fullers are used for making depressions in iron and steel. This process is called fullering. The top and bottom swages are used for rounding square iron or steel or reducing large sizes to smaller ones. Hot and cold chisels are both used for cutting iron. As the name shows, one is used for hot iron and one for cold iron. Gouges are for cutting ornamental shapes on sheet iron or steel, hot or cold. Calipers are used for measuring diameters. The broad flat surface of the flatter smoothes rough places. The set hammer is used to make square shoulders. It is a small hammer and does the work in narrow places which larger tools cannot reach. This sledge weighs about eight pounds. It is used where heavy hammering or driving is needed, and in conjunction with such tools as swages, fullers, set hammers, etc. The hardie is a sharp cutting tool used to cut small pieces of iron and soft steel while hot or cold. Tongs are of all sizes. Those most called into use have the following shapes: The shovel for the fire must be small and strong so the clinker formed on the bottom can be shoveled out without carrying too much coal with it. A poker, rake, and dipper also are needed for use about the fire.
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.
How to Make a Staple
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 41⁄2 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 61⁄4 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 61⁄4 ins. long.
Directions: Mark off with the centre punch 11⁄8 ins. on one end and 15⁄8 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 21⁄8 ins. long.
Repeat on the large end and draw this out until it measures 23⁄4 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.
Harness Hook
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, 31⁄4 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 11⁄2 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 21⁄2 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 11⁄16 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 131⁄2 × 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 11⁄16 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 11⁄2 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.
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.
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, 11⁄2 ins. in diameter up to 21⁄2 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.
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.
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.
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.
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.
Work Involving Flat Welds
Making a corner plate: This corner plate shows two pieces of metal, 1⁄4 × 1 × 6 ins. welded in the corners, upset. The ends of the pieces to be joined are scarfed as explained in the flat weld. Both pieces are heated, then one placed on the other, driven down, and welded. They are shaped upon the edge of the anvil, and the ends are cut off to the length shown by the drawing.
T weld: This is used in making a T plate. The cross piece is upset in the middle and scarfed by using the peen of the hammer as shown.
The upright piece is upset on the end and scarfed, same as was done on the corner weld. Both pieces prepared are then heated and welded as described in the making of the corner plate. The sketch given here shows fairly well the different steps.
XXIII — Mild Steel or Soft Steel
Mild steel, or soft steel, is supplanting wrought iron in many shops. Any smith who has worked with this metal will always prefer it to wrought iron. It is much stronger and can be bent, forged, and twisted in all manner of shapes, without cracking or splitting. This cannot be said of wrought iron. Therefore, when mild steel is used one is sure of finishing his problem, provided he understands the process of heating it. The matter of heating mild steel is the vital thing. It should never be worked at a welding heat or below a red heat. If worked either above or below this point it will show it by splitting or cracking before the problem is finished. Large crystals formed by working at or above the welding heat will cause the breaks, and internal fractures when working at the low heat will cause the cracks. However, this can be worked at a black red heat if the blows delivered affect only the surface and do not penetrate to the centre. This metal lends itself to forging better than wrought iron does. It is very good for most kinds of forging and particularly good for making weldless rings. One of the best problems to illustrate one of the many uses to which soft steel may be put is the making of a weldless ring.
A piece of soft steel 1 in. wide, 1⁄4 in. thick, 4 ins. long, is the stock used for this ring. With a centre-punch mark off 3⁄4 in. from each end. (See sketch.) In each centre-punch mark punch a 1⁄4-in. hole through the piece. With a hot chisel cut between these holes half way through on one side. Turn it upside down and finish cutting through from the other side. Now drive the chisel through, widening the slot out. Trim up the inside of the slot. Cut away all rough edges. Upset the piece on the anvil after heating and drive down on the ends. This will increase the size of the hole by shortening the length and bulging the sides out. The piece is now put on the horn of the anvil and rounded into a ring. The ends are now trimmed off or driven down into the thickness, as shown in the drawing. This is the method of making a weldless ring. It is easily made out of soft steel. It would require a very fine grade of wrought iron to do a piece of work of this kind, for wrought iron is fibrous and unless great care is exercised in forging it will split at the ends along the grain when opening it after the slot is cut in.
Steel is much cheaper than wrought iron, another good reason for its use. For the making of nuts, too, it is better than wrought iron. All one needs to do is to cut a piece off the end of a square bar, the proper thickness, punch a hole in it, and square it up. If wrought iron were used, to get the same strength one would need to bend the iron around a mandrel in the shape of a ring so that the grain of the iron would run around the hole of the nut. Then it should be welded and shaped into a square nut.
Chain Hook of Soft Steel
Up to the present time our work has been with wrought iron entirely. This hook is to be made out of soft Bessemer steel, which of course is very different from high carbon steel. It is the cheapest of the steels. All building material, railroad rails, boiler plates, steel cars, etc., are made of this cheap soft metal. The process of manufacture is quite simple. Molten cast iron, taken from the cupola, or blast furnace, is poured directly into a so-called Bessemer converter—a pear shaped vessel. Air is blown through the mass of molten metal. The air adds oxygen to the bath, and increases the heat to a temperature high enough to burn out all the impurities from the cast iron. This converts it into steel. It requires no more than nine or ten minutes to convert fifteen tons of cast iron into soft steel. The air is shut off and a sufficient amount of ferro-manganese is added so as to give the proper amount of carbon. The liquid steel is poured into ingots and these ingots while still hot are rolled into the shape used for the market. A piece of this kind of steel you are going to use to make a hook. Soft steel can be worked in the same way as you work wrought iron. It is not fibrous like wrought iron and is not apt to split unless worked at a low temperature.
Stock: Soft steel, 51⁄4 ins. long, 3⁄4 × 1⁄2 in.
Directions: The drawing gives all the steps necessary for the making of this hook. Notice in the drawing when the stock is given it is fullered down 11⁄8 ins. from one end. This is the amount needed to make the eye. After fullering the stock it is placed on the anvil and squared up.
These square corners are knocked down, making it round. When the body of the hook itself is drawn out, like the drawing, a hole is punched through the eye, using the same kind of punch as you did to make the nut. While using the punch keep cooling it off in cold water to prevent its getting hot; if you do not, the end is apt to burr and rivet itself into the iron. It also prevents its sticking into the hole. Place the ring of the eye on the point of the anvil and round up carefully with light blows from the hammer.
When rounded up drive the punch in again to the required size. This finishes the eye. The body of the piece is now gone over carefully with calipers and square to get the diameters and length. Bend the small point at right angles to the axis of the hook, like the drawing. Now it is ready for bending in the middle. Heat the middle very hot. Cool off the point about 1⁄2 in. Place the middle on the horn of the anvil and strike upon the small turned up cold nib to bend the hook from this point. By striking upon the cold end to bend it one can do so without destroying the shape. It will stand a lot of work upon it when cold.
When the hook is bent around as nearly like the drawing as you can, flatten it out at its widest part by laying it upon the anvil and striking with the hammer. The cross section of the drawing shows the shape that this flattened part should be.
This is what we call a solid eye hook. Another way of making an eye is to take round material of sufficient length to bend an eye on the end by placing the piece over the horn of the anvil. The body of the second hook can be made out of round iron, pointed down at the end and finished up the same as the first.
Bending a corner in iron and upsetting while bending: In this problem we bring in the making and bending of iron, so that the thickness at the corner must be sharp on the top side and rounding on the inside—without flaws or cold-shut. This bending method applies to all metals, whether of square iron or wide flat iron.
Stock: Piece 61⁄2 × 3⁄8 in. square.
Directions: Heat the metal in the middle and bend it over the rounding edge of the anvil.
When the piece is bent we still have to make it square on the outside and rounding on the inside. The bend just made should be placed in the fire and re-heated. Cool the stems off in the water to within one inch of the bend. Place the point of the cold stem on the anvil and strike on the hot corner. This is repeated on both outside corners until the piece assumes the shape of the drawing. This same result can be obtained by upsetting the metal in the centre before bending, as shown in the drawing.
Flat Wrenches
Wrenches are used for screwing nuts on bolts. They can be made in two ways: (1) One known as the solid wrench is made without welding, (2) the other, is made of wrought iron and is welded.
S wrench of soft steel: The sketch here is of a wrench made from soft steel 1⁄2 × 1 × 5 ins. Fuller down the stock edgewise as shown. Draw out the centre 1⁄4 in. thick and taper it from 3⁄4 to 5⁄8 × 5 ins. long. Cut the corner off, as shown by the dotted lines, and round the two ends up to the size given. Punch a 1⁄2-in. hole in the large end and a 3⁄8-in. hole in the small end of the bar. With a sharp chisel cut a V-shaped plug out of each end, tangent to the circles.
Jaws: The jaws of the wrench are finished with a tool called a wrench hardie, placed usually on the anvil for the purpose of finishing up work of this kind. Finish up both ends in the same way. Heat the wrench at the nick and cool the jaws off in water. Place the nick on the horn of the anvil and bend it as shown. Repeat on the other end. If the wrench is carefully made it will require no filing to fit the nut. These wrenches are sometimes polished and case hardened to prevent the jaws from wearing while in use.
Large flat wrench: A quick way to make a large wrench is to make it of wrought iron. A piece of iron 1 × 1⁄2 × 4 ins. is bent at almost a right angle. The inside corner is the corner made by the natural bend the metal takes when shaping it.
Scarf this corner by placing the peen of the hammer on the corner and striking the face of the hammer with the sledge or by using a bob punch if one is available, or it may be made by using the peen of the hammer without the use of a helper. Select a piece of round iron 7⁄8 in. in diameter. Upset the end of this and scarf it to fit the scarf made in the angle piece. Heat both pieces to a welding heat. Place them on the anvil and weld the handles to the jaws. The inside is rounded up at the same time the scarfs are being welded into place. Draw the points out to a short taper and bend them up in the shape of a wrench on the heel of the anvil. This is a simple way of making a large wrench that can be used for all kinds of work.
Alligator wrench: Stock 1 × 1⁄2 × 5 ins. steel. The alligator wrench is one of the handiest tools to have in a home or shop. For general repair work it is indispensable and is easily made. Mark off 11⁄2 ins. from the end of the stock. This is the jaw part. Place the other end of the stock in the fire. Take it out and from the centre-punch mark draw the handle out 3⁄4 in. wide, 3⁄8 × 8 ins. long, and tapering to 3⁄8 × 1⁄4 in. at the extreme end. The edges of the handle should be rounding. Place the jaw ends in the fire and heat red hot. Punch 1⁄4 in. hole back 11⁄2 in. from the end. Draw out the end and shape as shown in the drawing. With a three-cornered file, file the teeth on a slant and close together. This slanting will allow the wrench to let go of the work better than those filed at right angles to the axis of the piece. The teeth should slant backward and should be put only on one side of the jaw. Both jaws should be hardened and tempered a blue colour. To do this, heat the body of the steel back of the jaw to a red heat and plunge the whole into water one inch beyond the depth of the jaw. When cold take it out and polish. Draw the temper in the same way as you would for a knife blade. (See article on tempering and hardening.)
Socket Wrenches
Socket wrenches are useful for tightening nuts in places that are difficult to reach. It is most convenient when many nuts of the same size are used, as bolting shaft irons for vehicles, etc. Some are made to fit an auger brace; some have solid handles with a cross bar, and some have holes punched in the shanks to place the iron bars in while twisting the nut on the bolt. This drawing shows a style of wrench in general use. It can be made in two different ways. One is called the welding method, the other is the solid method.
Welding method: Cut a piece of metal 1⁄4 × 1 in. of Norway iron. The length of this bar must be determined by the size of the nut it is to be used for. Heat one end of the piece of iron and scarf it. Repeat on the other end. Bend the piece into a collar or ring, weld the two ends together, forming a cylinder about 1 in. deep—any diameter. Select a piece of round iron for the shank, the size depending upon the size of the socket. Upset one end of the round iron to fit the collar made.
Drive the shank into the collar about one half the depth of the collar, place it in the fire, and at a welding heat weld the collar to the shank. If the wrench is to be for a hexagonal nut, make a hexagonal drift pin (a square one for a square nut), and drive the pin into the collar. Place it all on a swage and round up with a top swage. Drive the collar down until it takes the shape of the drift pin. To do this successfully requires many heatings, and it can be done only while the metal is hot enough to yield always under the hammer blows. Should the drift pin stick after the collar is driven into it, place the pin on the anvil, giving it a slanting blow. This will loosen the pin and it will come out easily.
The shank should now be driven down as shown in the sketch, and two holes punched in at right angles to each other. These are holes to place iron bars for turning the wrench. These holes can be made in two ways: one, by forming lugs or bosses on the shank and punching holes in each one, or, a sharp tapered round punch, flat and sharp on the end, can be used to split the metal and force the sides out as the punch is driven in.
If the cross bar is to be used in place of the holes, a cleft scarf made in one end of the shank and a 3⁄8-in. bar of iron welded to this about 4 or 6 inches long on either side of the shank will act as a handle.
Open-sleeve or socket wrench: The wrench given here is for practically the same use as the one just described. It is lighter than the other. The opening is longer and allows the bolt to protrude through the nut without forcing the wrench off. This wrench is made of machine steel, and the size must be determined by the size of the nut.
For a small wrench take a bar of 3⁄8 × 11⁄4 × 6 in. soft steel. Mark off on the bar 2 ins. from each end and on these centre-punch marks fuller down on the top and the two sides so that the bottom of the fuller will measure 1⁄2 × 1⁄4 in. Draw these ends out to 1⁄2 × 1⁄4 in. any length. Cut the four corners off and make the centre round. Bend the two arms as shown and punch 1⁄2 in. hole through the boss. Be careful to prevent cold-shuts while doing this. Drive a drift pin into the hole and forge the shape as shown. Bend the two arms as shown and weld together. These should be worked down to a 1⁄2-in. round. The ends can be made into a brace shank by squaring the end and tapering it to fit the jaws of the brace. Or weld a piece of 1⁄2-in. round iron long enough to bend it into the shape of a brace, putting a round knob on the end for a hand hold. This makes a simple wrench and one that can be used in many places where flat wrenches are not convenient.
Open Wire Rope Socket
These sockets are made for wire cables, ropes, etc., and are best made of mild steel. Place the end of a 11⁄2-in. square bar in the fire and reduce it as shown in the sketch. Cut two outside corners off, as shown by the dotted lines. Round the ends up. Punch a 1⁄2-in. hole 2 ins. from the rounded end in the centre of the piece. Then cut a piece out with a sharp chisel, equal to the width of the hole. With the fuller, open the jaws out. Now cut the socket off 4 ins. from the rounded end and drill a 1⁄2-in. hole through this end of the socket. A drift pin 3⁄4 in. on one end and tapered to 3⁄8 in. on the other is now driven into the 1⁄2-in. hole at the jaw side.
Forge the shank as shown in the drawing while the drift pin is in. While forging keep driving the drift pin into the hole. When finished the hole should measure 3⁄4 in. at the large end and 1⁄2 in. at the small end. When the socket is finished cut the ends square and smooth up. During all the time the steel should never be worked below a red heat and most of the time at a high heat, below welding heat, until it is ready for finishing. Now the jaws are ready to be closed. This is done by placing a piece of flat iron, 3⁄4 in. thick and the width of the jaw, in between the opening, and close the jaws on this either with the hand hammer or a flatter. Drill a 1⁄2-in. hole in the middle of the end. This is made for the pin. Make a pin to fit this hole out of 1⁄2-in. round stock. Upset the end of the bar a little and place it in a heading tool, driving down and forming a head 1⁄8 in. thick and 3⁄4 in. in diameter. Take it out of the heading tool, cut the bolt off 1⁄2 in. longer than the width of the jaws. This allows for a 3⁄16-in. hole and pin. A small 3⁄16-in. hole is now drilled in the shank of the bolt and a split pin is put into the hole to prevent its falling out. The split pin is made by flattening down a piece of 1⁄8-in. wire in a small swage to a half round. Now double over to form an eye on one end of the two flat planes coming together. When this is put in through the hole, a chisel put in the opening will widen out the ends, thus preventing them from falling out.
Hinge and Butt
The hinge and butt are used on doors and gates. This fastening is made similar to the other hinges, except the eye is welded, instead of being a solid eye.
Stock: 1⁄4 × 1 × 71⁄2 ins. wrought iron.
Directions: The end of this piece of stock is bent around a drift pin as shown in the drawing and welded along the dotted lines. This is done by scarfing the end of the bar into a short tapered point. Bend it down at right angles about 3 in. from the end. Bend it in the opposite direction about 2⁄3 of the way around. Put in the drift pin. This now forms a hook shape. Continue the driving over until the scarf lies flat on the straight side. Take out the drift pin and weld the scarf to the body of the hinge. Drive the drift pin into the hole, shaping it up. The back of the hinge is perfectly straight so that it will lie flat upon the wooden door. The other end is drawn out, tapered and the end rounded up, and 1⁄4 in. holes punched in as shown.
The butt is made in the same way as you made the ornamental butt and hinge.
Bent hinges, such as are used on tail boards for wagons, railroad cars, etc., are simply ends of the iron piece bent around at a given diameter, with the under side flat, and the stock rolled up on one side. These hinges may be used in pairs. In that case a long rod is pushed through, connecting the two hinges.
Tongs
Tongs are used by blacksmiths to hold pieces of hot metal while working upon them.
Stock: Two pieces iron, 7⁄8 × 7⁄8 × 18 ins. Two pieces iron, 3⁄8 × 3⁄8 × 12 ins.
Directions: Mark off 2 ins. from one end of the 7⁄8 × 7⁄8 × 18 in. piece and heat it quite hot. This marked end is now placed on an anvil and flattened down to 1 × 2 × 7⁄16 in., leaving the shoulder as shown. (1) Heat the piece again. Place it upon the anvil, with the flattened piece extending beyond the anvil, and, with the shoulder on the outer edge of the anvil, flatten this down 1 in. wide, and 7⁄8 in. thick. (2) Then the shoulders should be at right angles to each other, as shown in the sketch. Re-heat the piece 1 in. from the last shoulder made. Reduce the shoulder (2), the iron to 9⁄16 × 7⁄16 in. (3) Notice that this shoulder is directly opposite the other. This completes the jaw of the tong. Draw out the end to about 3 ins. in length. It is now cut off the bar and another piece made just like it for the pair.
The reins or handles are welded to the small ends and tapered down as shown in the drawing, then rounded 41⁄2 ins. on the ends to 3⁄8 ins. in diameter. A hole is now punched through the eye of the jaw and a 3⁄8-in. rivet inserted. The little groove which you see in the jaw is put there with a fuller. This is done so that you can use it to hold small round iron as well as flat iron. The two parts are now riveted together. This is done either by making a head on a rivet and cutting it off, allowing about 3⁄8 in. for a head on the end that goes through the tongs, then heating the tongs and completing the riveting, or, as many smiths do, by putting a piece of straight 3⁄4-in. iron in, allowing 1⁄2 in. on each end plus the thickness of the parts of the tongs for riveting. This piece of iron is made very hot, put into the hole, and both heads are riveted on at the same time. It frequently happens that the rivet bends in the holes while hammering on the ends. This prevents the tongs from opening easily. If such is the case, put the rivet and jaws into the fire and heat red hot. Hold the handle, open and close the jaws while cooling. This not only centres the rivet but prevents sticking. The tongs should work smooth and free when cooled off in water.
XXIV — Hardening and Tempering: Tool Making
Effects of Carbon on Steel
What is commonly known as carbon steel is a metal composed of iron containing varying amounts of carbon. Steels containing much carbon are called tool steels to distinguish them from the low carbon steels. Tool steel, when heated red hot and plunged into cold water, will harden, while low carbon steel treated in the same way will not do so. This is an excellent way of testing two bars of steel for carbon when one is not able to distinguish grades of steel accurately. It is carbon that gives the hardening quality. When steel is heated it becomes red at 1000° F. At 1300° F. it passes a point at which it absorbs considerable heat without any increase in the temperature, showing that some change in the structure of the metal must be taking place. If the steel is heated above this point and allowed to cool slowly, a brightening of the colour may be noticed as it passes this point, known as the point of recalescence. The brightening is due to a liberation of the heat previously absorbed.
Method of heating steel in forge fires: All steel work, including tool dressing, hardening, and tempering, was formerly done in an ordinary forge fire. Now we have special furnaces for that purpose. However, in using a forge fire, care must be taken to insure good work. The fire must be very deep—that is, a large body of coke must be put between the tuyere, and the tool, so as to prevent the blast reducing the carbon on the surface of the steel. Sulphur will injure the quality of any steel tool. Hence, a fuel low in sulphur should be used. Charcoal is the best for this purpose, but the cost and the difficulty in maintaining the heat prevent its general use in blacksmith shops. If the coal does contain sulphur a great deal of it can be extracted or reduced by one making his own coke. This is done by burning the green coal to a coke and in this way driving off much of the sulphur. Gas furnaces or oil furnaces are used. This is much better than coal, for a uniform heat can be kept and an oxidation of the steel prevented. Whether natural or artificial gas is used, all that is necessary is to adjust the supply of gas in such a way that there will be a very slight excess of gas present beyond the proper amount for combustion. The presence of this gas excludes all air from the steel and therefore prevents its oxidizing the surface of the metal.
Heating in lead: In order to prevent oxidation molten lead makes a most satisfactory bath. The lead is melted in a cast-iron pot and heated in the forge. The steel must be left in the bath until it has all been heated to the required temperature. As the steel will float in the molten lead it must be weighted down to keep it submerged.
Hardening solutions: In many cases clear cold water is used in hardening steel. Some use soft or rain water. The temperature of the water for general work should not fall below the temperature of the shop; otherwise it would extract the heat too quickly from the steel and cause cracks or breaks in the work.
Salt solution: Salt is often added to water which is to be used as a hardening solution. (1) It increases the rate at which the bath will extract the heat from the steel; (2) it prevents the formation of steam on the surface of the water. Put as much salt in rain water as it will dissolve. This is considered one of the best and easiest made solutions for hardening steel.
Oil solution: Linseed oil, lard, cotton seed oil, whale oil, and melted tallow make good hardening solutions. They are used mostly for fine work. The oil prevents the sudden chilling of the steel and lessens the chances of cracking and breaking. Springs are mostly tempered in oil.
Metallic hardening baths: For very delicate tools mercury is sometimes used. It has a greater heat conductivity than any solution mentioned. However, the fumes given off are poisonous and for this reason it is not extensively used.
Tempering: The Part Colour Plays
When you buy steel for tools from a merchant he will assure you that the steel he sells you will harden at a cherry-red heat. This is true provided the metal has not been spoiled either by overheating it or working it at too low a heat during the making. This causes cracks or internal fractures.
If these directions for working steel are followed out a tool should harden at a cherry-red heat when plunged into water. When the steel is heated to the proper temperature, usually a cherry red, and plunged into a hardening solution, it will be very brittle, so that a file will not cut it. One test often used is to take a fine mill cut file and try to cut the hardened part of the tool. If it slips over the surface without cutting, the steel is considered hard; if the file cuts, the steel is not hard enough. Re-heat the steel hotter than before, cool it off in water, and test again. All cutting tools should possess a certain amount of hardness or toughness. When the steel has been plunged into cold water it is too hard for use. It is necessary to then reduce this hardness so that one can use the tool for the particular kind of work it is made to do. This process of reducing the hardness is commonly called drawing the temper, and the colour scheme plays a very important part in this operation. Perhaps the steps will be clearer if the process of drawing the temper on a cold chisel is explained: After the chisel is forged the proper shape, place the body of the tool in the fire, heat it red hot back of the point. Now heat the point to a uniform cherry-red heat, plunge 11⁄2 in. of this hot point into the water and hold it there until it is quite cold. This is determined by water clinging to the point when the chisel is taken out. Polish the part cooled off with a piece of emery stone, an old brickbat, or any rough polishing material. You will notice a group of temper colours starting from the point where the tool came into contact with the water. The heat in the body of the tool gives rise to these colours as it is conducted through the cold point of the steel. In this group of colours the first will be (1) pale yellow, (2) a full straw colour, (3) brown, (4) purple, (5) dark blue, (6) full blue, (7) light blue, (8) gray. This colour scheme corresponds to varying temperatures in the metal. The first colour (pale yellow) accompanies a temperature of 430°, while the last colour, gray, means a temperature of 700°. The colours show, too, a varying in the hardness or toughness of the steel. A cold chisel should be tempered a blue; so when the blue reaches the cutting end of the tool the end should be plunged immediately into water and cooled off. This is the principle of hardening and tempering all common tools.
However, these colours mean nothing so far as tempering is concerned unless the cutting edge of the steel has been thoroughly hardened. Then the colours have a real value. To prove that these colours are no test unless hardening precedes, take a piece of brass, or copper, or soft iron. Polish, then heat the piece in the fire to the temperature given here. You find the same set of colours, but you cannot use any of these metals for cutting tools.
The table of temper colours given in this book shows the colour required for tempering tools most commonly used.
Tempering of springs: Under the head of springs we may include every variety, from the small spring used in locks and fire-arms to the largest springs in use. They are made of spring steel of the required thickness, forged into shape, then hardened and tempered.
This hardening and tempering of springs is done in some cases by polishing and heating over a fire and drawing them to a blue colour. Then they are plunged into oil to fix the temper. Sometimes springs are heated red hot and cooled in oil, then held over the fire until the oil burns with a bright flame on the spring. It is then allowed to cool in the air. If the spring is found too hard, more oil is put on it and the operation is repeated until the desired spring movement is obtained.
Tool Making
It is possible for you to learn to make all of the tools you may need to use, including hammers. And not only will you be able to make blacksmiths’ tools, but such as are used by carpenters, bricklayers, stone-masons, machinists, etc. You must not expect to be able to do this work at first, but in a little while you will be able to replace your first working tools with those of your own make. From time to time, as the tools break or wear out, you can repair them or replace them with new ones. This gives excellent practice in forging and handling steel, and prepares you for more and more advanced work, an experience necessary for doing any work well.
Steel: There are many different grades of steel, depending upon the percentage of carbon contained in each. Steel low in carbon can be easily welded but cannot be tempered. Carbon steel is very difficult to weld and it can be done only by the use of borax or some other flux. High carbon steel or so-called tool steel, can be tempered. It is used for making cold chisels, files, drills, cutting tools, etc. Crucible steel: All tools are made from crucible cast steel. The cast steel is made by placing in a graphite crucible a certain amount of wrought iron and soft steel, and carbon is added in the form of manganese. These are all melted in furnaces. When melted they are poured into ingots and drawn or shaped to sizes for the market under different kinds of power hammers. These various size bars are used for the making of all kinds of tools. The tools we are going to make are (1) centre-punch, (2) cold chisel, (3) cape chisel, and (4) lathe tools. There are five lathe tools; (1) round nose, (2) diamond point, (3) side tool, (4) cutting off or parting tool, (5) inside or boring tool.
Centre-punch: You will find the centre-punch a most useful tool to have on hand. It is used for marking centres before drilling holes, starting points in work, etc. A small one is made out of a piece of 3⁄8-in. hexagonal tool steel, 3 ins. long. Put one end into the fire and taper it 3⁄8 in. long to 1⁄4 in. in diameter, as shown in the sketch. Make this end flat. Put the other end into the fire and draw it into a sharp tapered round point to about 1⁄16 in. on the end. This extreme point is ground to a very sharp point. The angles of the extreme should be about 45°. This is hardened and tempered a blue colour. Then it is ready for use.
Cold chisel: Cold chisels are usually made out of 5⁄8-in. hexagonal tool steel, 6 in. long. The form and dimensions are given here.
Heat one end of the bar and place it upon the anvil. Draw it out for the short end. This is the part upon which the hammering is done when the tool is finished. The surplus stock is cut off with a hot chisel and the short end is flattened. When cutting tool steel of any kind the chisel should be very sharp and the steel red hot. Put the other end of the bar into the fire, beginning back about 21⁄2 ins. from the end. Flatten it down to a chisel shape, as shown in the drawing. Cut the surplus stock off, harden and temper as explained before for the cold chisel.
Cape chisel: The drawing gives the form and the dimensions. The small end of this tool is forged out in the same way as you forged the small end of the cold chisel. Reverse the bar and heat the other end. Two inches back from the end fuller the metal down as shown in the drawing. Draw it out tapering. This end, too, is cut off, hardened and tempered as you did the cold chisel. Cape chisels are used mostly for cutting key ways in shafting. The point being wider than the rest of the blade gives clearance while cutting.
Lathe Tools
Round nose: The drawing gives the form and the dimensions.
Stock: A piece of 7⁄16 × 7⁄8 × 7 in. tool steel.
This size best fits the tool post of the lathe. You see by the sketch that one end is bevelled. This end is always made first. It is done by heating and chamfering the edges down with a hand hammer. Place the other end in the fire and draw it out to a sharp point in both directions. Throw the bevel on one side by placing the tool on the anvil and driving one side of the metal down to the other side. The point is now cut off on a bevel for clearance.
The drawing shows a cross section view of the tool. Notice that it is smaller on the bottom than on the cutting edge. This is done by reducing one side more than the other. The cutting edge of the tool should extend about 1⁄32 in. above the common level.
Hardening and tempering: All lathe tools of this type are hardened and tempered in the same way as you did the cold chisel. The temper colour of this tool is a very light straw. When this colour reaches the extreme point plunge the tool into water. The slight change of temperature does not materially lessen the degree of hardness, but it does toughen the tool so that it will do more work.
Diamond point: The form and dimensions are given.
Stock: 7 × 7⁄16 × 7⁄8 ins.
Heat one end and bevel it off as you did when making the round nose tool. Place the other end in the fire, 5⁄8 in. from the end, and fuller down to one half the thickness of the bar. This fullering is done on the bottom fuller, which is placed on the anvil. Re-heat this end, place it again on the fuller in the depression made, and with the hand hammer draw this end out and at the same time square it up into a diamond point by turning the tool at an angle of 45° with the anvil. Turn again, in exactly the opposite direction. Repeat this until the point of the tool is drawn out as shown by the sketch. The clearance should not be more than that shown. It is now cut off by placing the face of the diamond on the outer edge of the anvil. Place the cold chisel above this edge, strike the chisel with the sledge hammer and cut it off. If this is carefully done it will cut the proper bevel for the cutting edge. The drawing shows the slope of the cutting edge to be parallel to the top of the tool. The tool is hardened and tempered the same as the round nose tool.
Side tool (right hand): The form and dimensions are given here.
Stock: 7 × 7⁄8 × 7⁄16 in.
To make a tool of this kind bevel off the end of the stock, place the other end in the fire, and heat about two inches to a red heat. Take it out and place about one inch of this on the round edge of the anvil. With the hand hammer reduce the thickness of this steel, driving on the edge nearest you (see sketch marked A). The hammering reduces the thickness of the edge, which will be the cutting edge when finished. The part opposite to where you are working will be reduced very little. A chisel is now used for cutting the cutting edge on the tool (see B). Place the tool on a piece of soft iron, place the chisel along the line and cut through to the soft iron below. This gives not only a clear cut but prevents the chisel from driving in if it should strike the hard anvil. The clearance is cut off along the other lines. (C) The cutting edge is now offset. To do this use a set hammer. Push the part made beyond the anvil 1⁄4 in. Place the set hammer in this shoulder, drive down until the offset is driven down about 1⁄8 in. (D).
The method of tempering this tool is a little different from the way you have tempered other tools, on account of the length of the cutting edge, which should be hardened its full length. Place the end just finished in the fire and heat to a red heat. Plunge the whole tool into water. Take it out and polish the cutting edge with emery stone. Now place in the fire a piece of any kind of iron; 1 in. square will do. Heat it red hot, then place it upon the anvil, and lay the part of your tool that has been hardened on the hot bar. It will draw enough heat from the hot bar to produce the temper colours. This is one way to give a piece of hardened steel the heat to temper it when the body of that piece does not contain heat enough to do so.
Boring tool: Boring tools are made for the purpose of enlarging holes in cylinders, or any hole which should be enlarged after it has been drilled. The work to be done must determine the size and length of the boring tool. This is not true of any other one of the lathe tools.
Stock: 7 × 7⁄16 × 7⁄8 in.
Bevel one end. Place the other end in the fire and heat about 3 ins. of it. Draw it out to a tapering octagonal shape, as shown in the sketch. The end is pushed over the anvil about 1⁄2 in. Drive it down at right angles. The clearance for the cutting edge is cut off with a hot chisel and made ready for hardening and tempering.
Cutting-off or parting tool: This tool is made for dividing bars of metal into different lengths. The form and dimensions are here shown.
Stock: 7 × 7⁄8 × 7⁄16 in. tool steel.
Bevel one end. Place the other end in the fire and heat about 1 in. Place the fuller on the anvil. Put the top fuller on this, then put the steel between the two fullers about 1⁄2 in. from the end. Using the sledge hammer, drive down so that the centre thickness will measure 1⁄8 in. Draw the lump left on the end to 1⁄8 in. thickness, the same width as the tool. The drawing shows that the clearance on this tool is one half the thickness of the cutting edge, or 1⁄16 in. This clearance must be put on as shown in the drawing, otherwise the tool will not clear while doing the cutting. Finish up as shown in the sketch. Harden and temper in the same way as you did the round nose tool. Cutting off tools are made with the shoulder all on one side. (See sketch and see article on tempering steel.)
XXV — How to Harden, Soften, and Stretch Steel
Annealing or Softening of Steel
All steels that are worked under hammers and heated to any degree of temperature, when finished should be softened by heating, so that the unequal strains caused by the working of the metal may be neutralized. When the work is entirely finished it is placed in a furnace or forge fire and heated red hot. Then the fire is either withdrawn from the furnace, or the blast is shut off from the forge, and the metal is allowed to cool off as the fire goes down. This softens the metal and saves it from the danger of unequal strains.
Hard or high carbon steels are treated in a different way. The metal is heated red hot, then it is placed in a box filled with slack lime. The lime completely covers the piece. The cold air is prevented from striking it and cooling it off too quickly. When no lime is at hand wood ash can be used.
Sometimes the steel is heated red hot, then held until the red entirely disappears. Then it is plunged into cold water. This process is known as water annealing and is a process used for tool steel when quick work is required. It softens the metal so that it can be filed and worked quite easily.
Case Hardening
We have learned that carbon gives the hardening quality to steel. Since there is little carbon in soft steel and none in wrought iron, they will not harden as carbon steel does when heated red hot and plunged into water. But there are many small articles which are best made of this soft steel and iron and which must be hardened in some way to make them useful. In order to supply the lacking carbon the metal is put through a process known as case hardening. There are two methods of case hardening. The first method is to heat a piece of soft steel or iron red hot and cover the part to be hardened with cyanide of potassium. The metal will absorb the carbon out of the cyanide and when cooled in water will have taken on a hardened surface. If this is repeated two or three times the hard surface deepens.
Any drug store will sell you some cyanide of potassium. It comes in cakes. The cakes are broken up into small pieces. Be careful to keep the hands as much as possible from contact with the cyanide.
Set Screw
Set screws are made of soft metal, but the points must be hardened to resist the wear. This is done by heating the set screws red hot, then sticking the point into the cyanide until it cools off. Re-heat and repeat the work. During this time the iron is absorbing carbon. Heat again, plunge into cold water. The carbon forms a case on the end of the screw. Now you have a screw hard on the outside but of soft material in the inside. It is able to resist any shock that carbon steel itself could not stand.
The second method calls for the use of pulverized charcoal and bone. The principle is the same as in the first method. The iron articles to receive a case hardening are placed in a cast-iron box with a layer of charcoal above and a layer of bone dust below, alternating in this way until the box is filled to the top. The box is then placed in a heating furnace and heated to a temperature 1200° F. It is kept at this temperature from three to four hours. The articles all this time are absorbing charcoal from bone dust. The box is taken out of the furnace and plunged into a bath of cold water. From this cold bath it is plunged into a bath of boiling water, then taken out and dried. The pieces are oiled over slightly to bring out the colours. They have not only a hard exterior after this process, but they have a beautiful mottled surface of grays and blues, colours one often sees in parts of small guns, wrenches, etc.
Surgical instruments, guns, small wrenches, etc., are hardened in this way. The equipment for the second method is much more expensive than that for the first; however, the principles involved are the same in both cases.
Brazing
Brazing is a process of joining two pieces of metal by the use of another metal, such as brass or copper. The use of solder has been explained in the article on soldering. This article will tell about brazing of wrought iron, cast-iron, and steel in the forge fire.
One must bear in mind that when a forge fire is used for brazing, the fire should be free from green coal on account of the presence of sulphur. A reducing fire is best for that purpose. It is well to mention here that a forge fire that has been used for brazing must be thoroughly cleaned before it can be used again for any welding purposes. The brass will run down and clog the tuyere. If the least bit of smelter is left on the forge it is apt to mix with the coals. In that case it would find its way into the fire, melt, and collect on any iron that may be in the fire heating. The success of any of these operations depends absolutely upon a clean fire and a clean piece of work to be done.
To prepare the pieces to be brazed: All parts to be brazed should be free from any foreign matter. They should be filed or polished with emery cloth or sand-paper. This refers not only to the parts that come into contact with each other, but both sides of the contact edge for the depth of at least 1⁄2 in. When the parts are clean, put them together. See that the joints fit. Paint the joints with a flux made of boracic acid. Mix one part boiling water with one part borax and two parts boracic acid. Keep it pasty so that it can be handled with a brush. Ordinary borax can be used if the other is not at hand. The smelter (brass) can be bought at supply stores. However, brass filings, common sheet brass, or brass wire is just as good. If brass filings are used these should be mixed with the flux. Any old tin can will do for the mixing. A spoon for dipping the flux out when wanted can be made on the end of a rod 1⁄4 in. in diameter, about 20 ins. long, by flattening out an inch of the end, drawn out quite thin and fashioned spoon shaped. Place the parts to be brazed in the fire and heat till they are red hot. Dip the spoon into the brazing material and put a little of the smelter on the joints. Increase the heat. When the smelter begins to run add more. When it shows a bright streak all around the parts to be joined shut off the blast and let it cool before removing it from the fire. When it is black hot remove it from the fire and file into shape. Be very careful to see that the pieces to be brazed are so fastened together that they will not move apart when once put into place. This can be done by packing brick or clay around them or by clamping them in place. Do not put any weight that would cause any strain upon them, for when heated this would change the position and might cause a bend in the brazed parts.
Brazing of cast-iron: Cast-iron is prepared for brazing in the same way as steel or iron is prepared. The flux, however, is not the same. It is made up of boric acid, 8 oz.; pulverized chlorate of potash, 4 oz.; carbonate of iron, 3 oz. Mix these together thoroughly, breaking up all lumps that may be there. Keep this mixture in a glass jar. Place the pieces to be brazed in a fire as you did the iron and steel. Heat it all red hot. Mix the flux with the smelter and put it on. Do not put this on at any time before the metal is red hot. Increase the heat and add more flux and smelter. When the brass has flowed into the joints, shut off the heat and let the metal cool off in the fire. Cast-iron requires a higher temperature for brazing than iron or steel. If a brass rod is used in place of the smelter, push the end of the rod in the joint to be brazed. It will melt off as fast as it is pushed in. When brazing some cast-iron, the break should be reinforced on the unexposed side by a plate of wrought iron or steel. If this is cleaned off thoroughly and placed against the break the smelter will not only fill up the break but it will hold this piece of metal fast.
Brazing steel band saws: Band saws break very often while in use. They can be repaired only by brazing the broken ends together. Do so by filing each end of the broken pieces, tapering to a very sharp edge 3⁄4 in. in length for lapping over. The length of this lapping depends upon the width of the teeth of the saw. When the ends are filed, place them in a vise that can be bought for this purpose. If no vise is at hand two wood clamps, or iron clamps, or an ordinary shop vise will answer the purpose. Put the two ends overlapping in place, and clamp close enough to these ends to keep them in a straight line and, also, for shifting while brazing. Paint the joint with flux, using the first flux mentioned in the article. Put a piece of silver solder between the laps. Now heat the jaws of a pair of close tongs white hot, and grasp the joints between the hot jaws, and pinch them together. The heat in the tongs will melt the silver and braze the two parts. Hold the tongs steady; if not, they will bend, and the saw will be rather hard to straighten when the tongs are removed. Do not remove the tongs until they are black hot. Now place the saw in a vise and file the teeth to correspond to those on either side of the joint. Smooth the roughness from the joint.
The value of brazing: A knowledge of how to braze is most useful to any one working with the metals. Many things break that can be repaired only by this process. For instance, tubing, automobile parts, very complex parts of machinery, etc., when broken cannot be welded; they must be mended by brazing. The success of the process depends upon the care taken to make the parts perfectly clean and well fitted together. If this is well done the brazing material will find its way to the closest joints and fix them.
Processes of Stretching Iron or Steel
(1) Drawing: Stretching a piece of metal in one or more directions either by hammering, or pulling, or rolling, is called drawing. In the blacksmiths’ shop the term drawing always means a decrease in the size of a cross section of the piece and an increase in the length.
(2) Bending: Bending means making the metal take a shape from a straight line. It may be made into a circle or curved or bent at right angles.
(3) Twisting: In the process of twisting no change is made in the axis of the piece. The faces of the piece are changed; as for instance, when you twist a piece of paper holding one end fast and turning the other in the direction of its axis.
Upsetting: Upsetting means increasing the thickness of a piece of iron by shortening its length.
Forming: Forming is the process of giving a piece of iron shape, either by hammering or by using some forming machine; for example, the bulldog.
Welding: Welding means joining two pieces of iron together by heating them to the right temperature and hammering or pressing them together.
XXVI — Forging Hand Hammers
Cross peen hammer: The sketch shows the form and gives the dimensions of this hammer.
Stock: 7⁄8 in. square, 21⁄2 ins. long.
It is best to make this hammer on the end of a bar. In this way you dispense with the handling of tongs, and you are able to get the best control of your material. Mark with a centre-punch, the centre of the 21⁄2 in. piece. Through this, punch a hole with an eye punch. (See eye punch in tool list.) The hole will be a little less than the finished size. Draw the face end slightly tapering. Drive the four corners down and make the face of hammer octagonal in shape. The sketch will show just where to begin this knocking down. The hammer is now cut off and the face squared up. The centre of the face should be a little higher than the outer edges. Now drive into the eye a drift pin. This pin is made of 3⁄4 × 3⁄8 × 4 in. steel. It is tapered for the whole length down to 1⁄2 × 3⁄8 in., and oval in shape. It is driven into the hole. This gives the real shape to the eye of the hammer. Take the pin out and re-heat the hammer. Draw the cross peen out to a taper as you would if you were making a cold chisel. Be careful to keep all within the dimensions given. The hammer may now be filed and polished if one wishes a bright hammer; otherwise, it needs only to be tempered: then it is ready for use.
To temper the hammer: Place the whole hammer in the fire and heat it red hot. Grasp it with a pair of pick-up tongs through the eye. Dip the face in water half way up to the eye, and hold it there until the face is chilled off. Reverse by placing the peen end into the water. While this is cooling dip up enough water with the hand to keep the face of the hammer cold. Take it out and polish both ends with a piece of emery cloth wrapped around a piece of wood. The colours now are beginning to run from the middle toward the ends. When the purple colour reaches either end plunge that end into water, holding it in the water until the purple colour reaches the other end. Then plunge the whole hammer in water. This tempering darkens the hammer if it has been previously polished. Rubbing well with emery cloth again will restore the brightness. The hammer is ready for the handle. A hammer of this kind can be made without the help of a second person.
Round peen hammer: The form and dimensions for this hammer are given here.
Stock: A piece of 11⁄2-in. square tool steel. This hammer, too, is best made on the end of a bar about 20 ins. in length. With a centre-punch mark off 2 ins. from the end. This spot marks the centre of the eye. Place this end in the fire. One inch from the end fuller down on the four sides of the bar (1). This makes a neck one inch in diameter and having eight sides. Place it back in the fire and heat again. Now put the bar again on the fuller 2 ins. from the first fuller (1). This time fuller only two sides, the two sides opposite the centre-punch mark. Fuller so that the thickness measures 11⁄4 ins. This means only 1⁄8 in. depression on the two sides. Put again into the fire and draw the first end out so that it measures 1 in. octagonal, any length. (See sketch 2.) Heat again, this time the whole body of the piece. Punch a hole with the eye-punch where the centre-punch was made. The hole will be a little less in size than the finished hole will be (see sketch) to allow for the increase in size while working the metal into shape. Put the drift pin into the hole. Drive it through until the small end just shows through on the other side. Place a fuller over the hole and work the metal out sidewise by striking on the top of the fuller with a sledge hammer. This requires a helper to do the heavy work. While the heavy work is being done the steel must be heated many times, but always without the drift pin. Keep the drift pin in water while the hammer is being heated, as the pin must always be cold when driven into the eye. Drive it in a little farther each time, so that by the time the centre is finished the hole will be the proper size (3). The thickness of the metal around the eye should be about 1⁄8 in. on the outer edges and 3⁄16 in. in the centre. This tapers a little from the centre outward, as is shown in the drawings. Put the 3⁄4-in. bottom fuller on the anvil and place the neck of the hammer on this and a top fuller above that. Strike on the fuller and reduce the neck until it measures about 3⁄4 in. in diameter, keeping the octagonal shape all the while.
Heat the hammer again where the face should be, and fuller down between the body and the face so that this will measure about 11⁄8 in. square, using the same large fullers as before and making it octagonal. This finishes up completely the body of the hammer between the face and the peen.
With a sharp chisel cut the hammer off an inch and a half from the body. You will then have enough stock for the face of the hammer.
The surplus stock on the peen allows for holding with the tongs, and the face of the hammer is rounded up to about 15⁄8 in. in diameter. Bevel the edges down 1⁄16 in. back of this face and, with a sharp chisel, trim the face off flat or square with the axis of the hammer. The centre of the face should be a little higher than the outside edges.
Grasp the face with the tongs and place the peen in the fire. Take it out and cut it off 1 in. in length and make the edges rounding. To shape the peen, place the neck on a large fuller and round up as shown in the picture. Be careful each time to give it one eighth of a turn so that the octagonal shape will not be lost. If the hammer has been carefully forged it will require little finishing in the way of filing, unless one wishes to make a fancy polished hammer. If such a one is desired some draw filing and polishing must be done. This makes the hammer look better, but it doesn’t increase its efficiency. The tempering is done in the same way as the tempering for the cross peen hammer was done. However, this hammer is larger and heavier than the cross peen hammer and is more difficult to temper. While the same principle is involved in the tempering of both hammers, greater care must be taken in tempering this one.
The handle is placed. You will find that the driving of the drift pin into the eye, first on one side and then on the other, makes both outside openings larger than the centre. This should be so, as it helps to hold the handle firmly in place.
Tool Steel and the Making of Tools
Here are a few problems which deal with the making of your own tools. When buying steel for this work always tell what the steel is to be used for. The merchant will probably recommend to you a grade of steel from which you can make tools that will last.
Hardie: Take a piece of 11⁄8-in. square tool steel. Make this tool on the end of a bar if the bar is long enough. It is easier handled in that way. The dotted lines on the drawing show the amount of material required to make the shank. This should be made to fit the hole in the anvil; 3⁄8 in. from the shank fuller down on the two sides of the steel, leaving 5⁄8-in. thickness between the fuller marks. Draw the end out to a 3-in. taper on one side and widen it out to 13⁄4-in. taper on the other. (See drawing.)
Set hammer: A set hammer is made with a piece of 11⁄8-in. square steel; 15⁄8 in. from one end mark the hole. Put one end of the bar into the fire and heat it. Take it out and punch a hole with the eye punch in the piece of steel when it is marked. Knock the four corners down, bevelling them as shown in the sketch, and trim the end off rounding for the head. Cut it off 4 ins. long; fuller the four corners 11⁄4 ins. from the face as shown in the sketch. The end view of the drawing shows the depth of the fuller marks.
Hot chisel: This tool is made much as you make the set hammer. However, where the set hammer is fullered on the corners the hot chisel is fullered on the two sides, and the end is drawn out tapering. Used to cut hot iron. (See drawing).
Cold chisel: This tool is made out of 1-in. square stock. The punching of the eye and head part of this chisel is made in the same way as the other tools described here. A blade is tempered from the centre to 23⁄4 ins. in length, and the cutting edge is finished a little rounding. This tool is made to cut cold iron, hence its name.
XXVII — Some General Forging Problems
Ice shaver: Ice shavers are useful as shavers, breakers and choppers of ice. They are made out of a piece of low carbon steel for the blade and a piece of 5⁄8-in. round iron for the handle.
Directions: Take a piece of 1⁄2 × 6 × 4 ins., and cut along as shown by the lines. When these two corners are cut out, point the centre piece for a cleft weld. Slit the end of the rod, scarfing its points thin, and slip this point into the crotch of the scarf, and weld with borax. This now gives you a piece that looks like a shovel. On the other end of the handle bend a ring about 4 ins. in diameter. Place the flat end in the fire, heat it up, and taper this flat end down very thin, about 1 in. long. With a file, file four teeth in the end, the same shape as shown here. It is now ready for tempering. This is done by heating all the teeth well back toward the handle red hot. Plunge the whole thing into water to cool it off. Take it out and polish. Heat a piece of large iron in the fire red hot. On this piece of metal place the teeth of the pick. When the blue colour appears on the point and cutting edges of the teeth, cool in water. It is now ready for use.
Grub hoe: The form and dimensions of this tool are given, also the different steps in the process of forging.
Stock: 11⁄4 × 3⁄4 × 5 in. steel.
Directions: Mark off with a centre-punch the middle of the piece of stock, and then mark off 1 in. from the middle in either direction. Fuller, as shown in the sketch, on the first end, to a depth of 1 in. Heat the piece and fuller the other end to a depth of 1⁄2 in. (A). The centre lug is now 2 ins. long. To make this 2 ins. long it is necessary that the fuller be placed on the piece on the outside of the centre-punch marks. Draw out the two ends, as shown by the sketch, one being directly opposite the other. Punch a hole with the eye punch in the middle of this lug almost through on one side. Take the punch out, turn the piece upside down, and finish punching the hole. The punch used for doing this part of the work should be straight and tapered and quite thin on the end. The problem is not to cut out a large piece but rather to split the metal. It’s only 3⁄4 in. wide and will not allow for the cutting away of any material. A punch of this kind will heat up on the end while driving, when it is apt to bend. To avoid this keep it cold by dipping it into water from time to time. Place a little green coal in the hole after you have started the punch in. This prevents its sticking in the hole and it also prevents the end of the punch from getting hot. A very deep, narrow slot can be punched successfully in this way.
The drift pin used to shape the eye upon should be made the size of the finished hole—that is, 11⁄2 × 3⁄4 in. and 6 ins. long—oval-shaped, and tapered on the small end to 3⁄8 × 1⁄4 in. This taper should be the whole length of the drift pin. Drive the pin into the hole about half way down. This widens the hole so that it can now be placed on the horn of the anvil and fullered to the required thickness, which should be 1⁄8 in. on the extreme edge of the eye. Drive the drift pin again about 4 ins. or 5 ins. At the same time work the metal down on the outside. Repeat this till the hole fits the drift pin. The pin is now driven in through from the other side, thus making both outside openings of the eye the same size. The hoe is now finished up as shown in the sketch and ready for hardening and tempering.
This is done in the same way as you did the chisel and the same temper colour is used for both. Five pounds is considered about the right weight for a hoe of this kind. The problem of working out the eye for this is the same as for making the eyes of picks, hatchets, and tools of similar design.
Turnbuckles
Turnbuckles, made either of steel or iron, are used for truss rods. There are many ways of making turnbuckles. Out of all, three methods are here given: (1) Solid forged buckle, (2) welding up, (3) pipe method.
Solid forged buckle: This is made of soft steel. Select a piece of 11⁄2-in. square stock 6 ins. long. Mark off 2 ins. with a centre-punch on each end. Draw the ends out 1 in. round. Bend the ends down as shown at B. Forge the buckle part to 11⁄4 in. round at the end, as shown at C. Make the other end just like this one and weld the two ends together so that the total length will be 10 ins. Now drill holes in each end for a 3⁄4-in. tap. Tap a right-hand thread in one end and a left-hand thread in the other end, or you can put a swivel hook in one end in place of the thread. To do this the hole should be drilled 7⁄8 in. without a thread. Select a piece of 7⁄8-in. round soft steel 10 ins. long. Upset the end and work a tapered round head on as shown at D. The head should be 1 in. long and large enough to work loosely in the slot. Put this into the hole with the head between the wings and point the end forming it into a hook.
Second method: This is done by welding the two rods to collars. Make two collars out of wrought iron, the size depending upon the size of the turnbuckle. Scrape the ends of this flat iron, bend each into a circle, and weld on the horn of the anvil, thus making two collars. The arm should be drawn out of a piece of flat iron and made half round by a swage on the anvil. This leaves the original thickness of the bar on each end of the piece drawn out. These ends are now flattened and scraped as shown at A and should be wrenched to lap on the inside of the collars. Place one collar on one end and the wings opposite each other. Push a bar of iron into the opening within an inch of the collar. This bar prevents the tongs from squeezing the two wings out of shape and loosening up the collar while welding. Grasp the turnbuckle with a pair of tongs and place the end in the fire. Take a welding heat and weld this down on the horn of the anvil. At the same time shape it as shown at B. Draw out the piece of iron, place the other collar in the open end, and weld it as you did the first. This is finished up in the holes made. Threads can be cut or swivel hooks can be placed in.
Third method: Take a piece of pipe, length and size desired. Heat one end and upset it, enlarging and thickening it slightly. Cut a round iron plug to fit this end tightly. Heat the plug and drive it into the pipe. Place it on the fire and weld the pipe to the plug. At the same time forge the end square or hexagonal. Drill a hole in this end, pin the swivel hook same as explained in the second method. Select the iron, make the head on the rod, and put it through the pipe into the hole, head inside, before the plug is welded in the other end. Be sure that this rod will turn freely. Shape the hook before the plug is welded in the 2-in. end. This gives one an opportunity to push a rod into the pipe and hold the head of the hook while shaping it in the form of a hook or eye as required.
Now weld a plug in the other end the same as you did in the first. Drill a hole in this end and cut a thread to receive the truss rod end. This last method is much simpler than the other two. It has this advantage, that the thread will not rust so quickly, since it is always enclosed in the pipe. However, there is danger of a very weak spot right back of the plug, because you know when two pieces of metal are welded together the temperature should be the same. If not, the cold one will cut into the hot one and form cold shuts. In this case it is impossible to get the plug the same temperature as the outside. As a consequence there is a defect in the forging.
Eccentric strap: The principles applied in the working out of this problem are used in making many articles of wrought iron. Eccentric straps are much used in foundries, machine shops, and general shop work.
Stock: Bar of wrought iron or soft steel 11⁄8 ins. square, 16 ins. or 20 ins. long.
Round the bar down on one end to 1 in. in diameter. Split the other end up the length of the bar 8 ins. to within 1 in. of the shoulder made by the rounding down of the stock. These two arms are now thrown at right angles to the stem, forged down to 1⁄2 × 1 in. the entire length. The arc of the circle made by the arms is determined by the size of the thing the eccentric strap is meant to fit when it is finished. The ends are now turned up at right angles and are bent to fit the circle. A gouge chisel will cut the end off rounding. All ladle handles can be made in this way.
Garden hoe: The drawing shows the form and dimensions of the hoe, a garden tool very simple in construction and very useful.
Stock: 6 × 4 × 1⁄2 in. steel.
Directions: Mark off 2 ins. at one end and cut down 1 in. deep on both edges. Cut out a wedge-shaped piece as shown in the sketch. Draw out the piece 1⁄2 in. in diameter and 6 ins. long. This forms the handle. Fuller down on each side of the handle where it joins the body as shown by the full lines. With the fuller spread out the metal on either side of the handle until it forms a blade 8 × 5 ins. This blade should be 3⁄16 in. thick at the top and 1⁄8 in. at the cutting edge. Bend the handle into shape. File or grind the edges of the blade to make it smooth. This should be tempered by heating it red hot. Plunge into oil. Take it out when cold and hold it over the fire until the oil flashes off. Then allow it to cool in the air. Grind it and polish if a bright finish is required. If not it is now ready for the wood handle.
Wood chisel: Chisels for cutting wood can be made from a piece of gas pipe and a piece of steel, or from old cold chisels too short for use. If no piece of old tool steel is at hand take a new piece, 5⁄8 × 4 ins., hexagonal.
If a piece of gas pipe is used, 1⁄2 in., heat one end and place it on the point of the horn of the anvil. With the peen hammer thin the point down around the end. This thinning stretches the metal and gives you a funnel-shaped opening, and a scarf to use for welding. The short chisel end should be pushed into this for about 1 in. and the scarf should be tapped down gently on this chisel. Sometimes it is necessary to upset the end of the chisel in order to make it fit the scarf. If required to do this, put it into the fire and heat it red hot, and upset it on the end where the weld is to be. Now put it into the pipe, put borax on the scarf, and heat it hot enough to weld. Take it out and weld it up in a bottom swage and reduce the weld to 1⁄2 in. in diameter. Cut the shank off about 31⁄2 ins. from the weld and heat this end again. Stretch it on this end so as to enlarge it to fit the wood handle which will be placed in later. Heat the steel end. Flatten it down to the shape of a wood chisel, the width to be according to the size needed. Out of this piece of steel a chisel 1⁄2 in., 3⁄4 in., or 1 in. can be made. It should be tapered down 3⁄4 in. on the cutting edge. File the cutting edge on the chisel. It gives a much better finish. The chisel is hardened and tempered almost the length of the whole blade, a blue colour, by heating it red hot, plunging it into water, polishing, and drawing the temper on a hot piece of iron. The handle is made by using what is known as a hollow auger. This shapes the wood to fit the pipe. A piece of the same pipe can be sawed off with a hack saw about 3⁄8 in. wide. This makes an iron ring, which should be driven in the end of the wood handle to prevent it from splitting. These chisels make the best kind of tools for rough, heavy work.
Door hasp: Door hasps are found most commonly on barn doors and gates, and in conjunction with a staple and lock form a complete fastening. The drawings make clear the different steps in the work.
Stock: 1⁄4 × 1 × 6 ins.
Directions: The eye is made first. Heat the piece red hot. Fuller down the stick 5⁄8 in. from one end, and 2 ins. from the fullered mark put in another. The distance between the fullered marks should be 2 ins. Draw out the space between the fullered marks to 5⁄8 in. in width, 21⁄2 ins. long. Cut the corners off the piece left on the end, as shown by the drawing. Round this up with the hammer on the anvil. Punch a hole in the middle of the eye, but keep the thickness the same during all the work. To make the body of the piece, where the slot is, 2 ins. from the shoulder fuller the end down to 5⁄16 in. from the end. Draw out this end to 15⁄16 in. in length. This forms the loop, and at the same time it tapers to a sharp end. (See drawing.) The piece is now ready for punching. Mark places for the punch holes, then cut between the holes with a hot chisel. In this way the centre piece is cut out, forming the slot. If this is carefully done little work will be required to finish it. The slot is filed out if any rough places are left. The end is bent up. Sometimes a ring is put in it, as a door pull, and sometimes the latch itself is used for the pull.
Pair of dividers: Perhaps the simplest way to make a pair of dividers is to get a pair of buggy top joint butts, 1⁄2 in. size. Weld to each of the legs a piece of steel to form the two legs for the dividers. Begin about 1 in. back of the weld and draw the legs out tapering, octagonal in shape and rounding toward extreme sharp points. Place a washer on each side of the joint, and rivet the ends together with a steel rivet. If carefully done the dividers will require no wings. If wings are required they can be made by punching a slot 1⁄2 × 1⁄8 in. in each of the legs, 2 ins. from the joint. In each of these slots drill holes, in one a 1⁄8-in. hole and in the other a hole for a 3⁄16-in. tap. Drill both sets of holes through the legs. Tap out the one and make a thumb screw to fit. This is done by drawing out a 3⁄8-in. stem on the end of a 3⁄8-in. rod and cutting off 3⁄8 in. of this to form the head of the thumb screw. Heat this end and flatten down. Finish up with a few strokes of the file. Cut a 3⁄16-in. thread on the end. Screw it into the dividers. Draw out a wing 3⁄8 in. wide, 1⁄8 in. thick, to fit the slot. Bend it into a semicircle and place it into the slot. Open the dividers. See that it swings round on this circle. Drill a small hole in the end of the wing to fit the 1⁄8-in. hole drilled into the leg and rivet it into the slot. This makes a pair of dividers that can be used for all classes of work.
Stone Chisels and Picks
1. Stone chisels:
Stock: 1⁄4, 1⁄2, 5⁄8, 3⁄4-in. octagonal steel, 5 ins. long. Stone chisels are made out of the above sizes of steel, in sets, for the cutting of marble, sandstone, granite, etc.
Directions: Put one end of the stock in fire. Heat about 1 in. Draw this hot end to a taper 1⁄4 in. at the small end and 11⁄2 in. long. Place the extreme end again in the fire, take it out and strike it on the end by placing it upright on the anvil. Upset this end and form the round top shown in the drawing. If this top is not completed in one heating, heat it again and repeat the hammering on the end. All stone chisels are made with this rounding end so that wood mallets can be used for driving purposes. The ones shown here are the shapes used on most stone chisels.
The size of the teeth depends upon the hardness or softness of the material to be cut. The large teeth are used for hard stone cutting and the small teeth for soft stone cutting. Place the other end of the tool in the fire and flatten it down as shown in the sketch given here. Notice the dotted lines show that the extreme cutting edge of this tool is narrower than the body. This is an allowance made for the spreading out of the tool while cutting the teeth. Space off the teeth with a 3-cornered file as shown in the same sketch, and cut the teeth with a chisel made in the following way: Take a piece of 1⁄2-in. octagonal steel. Draw it out in the shape of a cape chisel. (See sketch.) Heat the end of the steel tool, then place it in the vise. With the end projecting up place the chisel on the mark made by the file, strike down sharply on the chisel, and drive it down to the required depth. This is repeated until the teeth are all cut. Flatten the cutting edge carefully on the anvil, and all teeth that may have been driven out of a straight line by the cutting. Heat the tool to soften it. File between the teeth the roughness made by the forging of the tool. A small flat jewellers’ file will be found best for this purpose. Harden the tool as you did the cold chisel, and temper it at the purple colour sign.
2. Pick:
Stock: 1⁄2-in. square tool steel, 8 ins.
Directions: Mark the middle of the bar with a centre-punch. Punch the hole through with the eye punch. Put in a drift pin and flatten down the bulged sides of the bar made by punching the hole. Draw the two ends out to a sharp square point. This should make the pick not more than 10 ins. long. The drawing should show the shape it will be when finished. These picks are hardened the same as cold chisels, and tempered at the purple colour.
Rock Drills (Used With Machinery)
As the name indicates, these drills are used for making holes in rocks when blasting is to be done. The form and shapes most in use are shown here.
The double drill, used so much in power drilling machines, is made in the following way: Take a 1-in. octagonal bar of steel, any length. Heat one end, and upset it to 11⁄4 in. in diameter. Put a small 1⁄2-in. fuller on the anvil and place the end of the bar lengthwise on the fuller. Put the top fuller directly above this and strike with a sledge hammer. The result is two fuller marks driven down within 1⁄2 in. of meeting. Reverse this and do the same on the other two sides. This marks a cross.
Place the forming tool in the anvil, and with a set hammer forge out the wings as shown in the sketch. The diameter of the drill depends upon the size of the hole to be drilled and is made accordingly. Use a sharp chisel for cutting the cutting edges of the drill. It is now ready for tempering. Drills are made in this way from the raw material. When once made they are kept in shape by what is known as the drill dressing tool shown here. These rock drills wear out on the sides, thus reducing the diameter. When re-dressing they are always upset to the required diameter. The re-dressing is done in the following way: Heat the end of the drill in the fire and place the dressing tool so that the cross impression fits the end of the drill. Drive on the end lengthwise of the bar, upsetting the drill to the required diameter, at the same time retaining the original shape of the cutting edge of the drill.
To temper rock drills: Take two small tubs of cold water, one clear and the other made soapy by cutting up a bar of cheap soap into bits. Heat the end of the drill to be tempered to a dull red and put it into the tub of clear water, the cutting edge only under water until it is cooled off. Take it out to polish. When the straw colour appears plunge it into the tub of soapy water. This does away with any red heat that might be in the bar when the temper colours appear. Soapy water is a poor conductor of heat and it allows the steel to cool off without suddenly chilling it.
Drill for Hand Drilling
These drills are used for drilling holes in rocks where it is impossible to place machines or where machines are not available, such as on farms, where great rocks and nigger heads are to be removed by drilling and blasting out.
They are made as you would make a cold chisel. The taper, however, is much shorter and the ends are usually either rounded or diamond shape. (See sketch.) The cutting edges are ground, but in many cases they are forged and filed to shape. They are tempered in the same way as cold chisels are treated.
Round and flat hand drill: Take a piece of octagonal steel, the size and length depending upon the size and depth of the hole to be drilled. These should not be over 20 ins. in length, for the blow would have little effect upon the cutting edge of the drill. Put one end into the fire, take it out and finish it up as you would the short end of a cold chisel. Reverse the piece of steel, and heat this end, for about two inches, red hot. Place it on the side of the anvil face and flatten it down tapering. Make it very short and just wide enough for the size hole to be drilled. With a hot chisel cut the end into the proper shape, either round or diamond shape. With the hand hammer work the cutting edge on the end. This end should be from 1⁄8 in. to 3⁄16 in. in thickness. Either file or grind the bevel which forms the cutting edge sharp. Harden and temper it the same as you would a cold chisel. If it is found, on trial, to be too soft, re-heat, harden, and temper at a higher colour. One of the best hand drills for drilling holes in soft material like bricks or sandstones is a piece of gas pipe any length. File teeth in the end, like a saw tooth. Case harden the end. This drill will go through a wall almost as quickly as a twist drill and with much less labour.
Shackle
Shackles are used for connecting chains, wire, ropes, etc.
Stock: One piece of 3⁄4-in. round iron, 121⁄2 ins. (for shackle). One piece of 1⁄2-in. round iron, 4 ins. (for pin). One piece 1 × 1⁄8-in. flat iron, 13⁄4 ins. (for key). One piece 3⁄16-in. round iron, 21⁄4 ins. (for ring).
Directions: Heat the 3⁄4-in. round iron bar two inches, then bend this end on the anvil at right angles to the rest of the bar. Place the heel on the anvil, with the end sticking up. Strike on the end with the hand hammer and drive it down into the heel of the piece. Repeat on the other end of the bar. As one can always force the metal into any shape one desires by first driving it one way or the other, skill in making the two ends of the bar depends upon one’s way of using the hammer. This method of making the eye on the end of the bar does away with welding and upsetting of the metal. A round finished eye is the result of the natural bending of the metal. This holds good not only for the shackles like this one but for many other tools, such as hand holds for cars, wagons, etc.
Bending: The shackle should be bent as shown in the sketch. First bend it right back of the eye, each one at about 45°. Heat the body of the piece and shape it around the horn of the anvil until the opening measures 1 in. wide. The sledge and swage are best used for this purpose. Place the swage on the metal and have the helper strike the swage. The shape is not apt to be changed or the metal marred if these tools are used.
Pin: Take the 1⁄2 × 4 in. piece of stock. The end is heated and upset about 1⁄2 in. Place this end in a heading tool and work a button head on the end with either the cupping tool or a hand hammer. The pin should have a slot cut through it 2 ins. from the head. To do this make a punch to cut the slot the shape required. After the piece is marked punch the slot by driving the punch half way through on one side. Turn the piece over and drive the hole through on the other side. This enlarges the metal a little. Reduce it to the 1⁄2-in. size to fit the hole in the shackle. Cut a little piece of iron the thickness and width of the key, 1⁄2 in. long. Heat the end with the hole in and drive this drift into the slot. With 1⁄2 in. top and bottom swage and the drift in the slot, reduce the pin to fit the hole. Drive the drift out. You now have a nice rounded pin with a hole in, 3⁄8 × 1⁄8 in.
Key: Take a piece of 1 × 1⁄8 in. flat iron or steel. Mark the shape of the key. Cut it out and file to fit the slot. Drill holes in the small end of this to prevent it falling out of the pin.
Ring: Bend the piece of 3⁄16-in. wire around a 5⁄8-in. rod in the shape of a spiral and saw off each ring as required. The ring should fit the hole in the key. This method of making a shackle is the same whether the material is 1⁄4 in. in diameter or any size up to 2 ins. in diameter.
Crow-Bars, and Welding of Tool Steel to Wrought Iron
Crow-bars are made by welding a piece of round No. 2 flat steel into the end of a wrought iron bar any length or any size, depending upon the use to which the bar is to be put when made. This drawing shows a bar for shifting rails for railroads. When the size is determined, select the wrought iron to be used. Upset the end and split it with a chisel 3⁄4 in. for a cleft weld. Re-heat the end to a white heat. Place it upon the edge of the anvil nearest you and with the peen of the hammer work the scarf out to a sharp point. Repeat on the other side. (See picture.) Place the piece of steel selected for welding, in the fire; shape this end down to a sharp point at an angle of 45°. With the edge of the chisel placed on this scarf, strike on the top of the chisel with a sledge hammer. This will cut a nick and at the same time it raises up a sliver which will help hold the piece of steel in the iron between the cleft. Cool this scarf off in water until it is black hot. Heat the piece of iron (scarf end). Place the end of the steel scarf between the cleft and close the scarf on to the steel by striking gently. The steel will now stay in the end of the piece until it is welded. Place the scarf in the fire and when it is red hot cover it with borax. Get a welding heat on the wrought iron close to the joint first. Gradually work this heat toward the steel till the borax begins to burn, emitting a dark brown smoke. Take it out of the fire and place it on the anvil. One or two sharp blows on the end of the steel will drive it up into the crotch of the scarf. Now strike gently on the top of the scarf. Increase the force of the blows when you are sure the two pieces are welding together. If the pieces are not welding, which will be readily seen by the points of the scarf opening while working them down, place them again in the fire, put on borax and re-heat. A few trials will teach you how hot to get it for welding. Flatten down the end and shape it as shown in the drawing. Harden and temper the crow-bar as you would a cold chisel. If the point is not quite sharp enough grind it on the stone.
Nail Puller or Claw Tool
This tool is made in much the same way as you make a crow bar. However, before bending the end up into a crow-bar shape, cut a slot in the end, as shown in the picture. Now bend it into shape. The handle should not be over 20 ins. in length and tapered usually from 3⁄4 in. at the large end to about 3⁄8 in. at the smaller end. The end is now flattened and a hole punched in it to hang it up when not in use. This is one of the handiest tools to have around any shop, not only as a nail and a bolt puller, but it may be used in place of the crow-bar. The drawing explains the various steps in the making of the tool.
Butcher Knife
Stock: Spring steel, 7⁄8 × 1⁄16 in. × 9 ins. long.
The spring steel used for carving knives or any steel used for that purpose should be a grade that will harden in oil just hard enough to feel a mill-cut file cut the steel. Cut the stock off 9 ins. and forge the shank first. On this size steel this forging of the shank consists in reducing the thickness of the material and widening it about 1⁄16 in. to 2 ins. in length. This tends to toughen the steel, and it makes a better knife by this extra work.
To forge the blade, heat 7 ins. and bend it a little edgewise before reducing the one side for cutting edge. Allow the stretching and thinning out of this edge to straighten the blade, and the curve on the back will form itself, naturally, by the extra length of the cutting edge. Do not try to forge the exact shape of the knife. It is much better to reduce it to the required thickness, outline the shape, and cut it with a hot or cold chisel. At this thickness the knife can be worked either hot or cold when doing this particular kind of work. Cut along the outline, thus giving it shape. A fine file will finish the roughness on the outline and trim up any uneven spots caused by the shaping. When the knife is finished, so far as the forging is concerned, anneal it by heating the whole blade and allowing it to cool in slaked lime. This relieves any strain due to forging. Handles are made of bone, birch, or beech, and can be shaped to suit one’s taste. They should measure about 1 × 5⁄8 × 5 ins. Rivets hold them in place. (See cut.) These are of brass wire, easily made by cutting off the length required to go through the wood to hold the blade in place. Place the blade in the slot of the wood handle and drill four holes through the wood and through the blade. Do not make the holes more than 1⁄16 in. in diameter. Take the blade out, harden, and temper. All drilling of holes and fitting should be done before the blade is tempered, while it is in the soft state. It is difficult to drill the holes after the tempering has been done.
To temper the blade: The blade is tempered by heating it on a coke fire. Place the back of the blade down, on a piece of flat iron. The iron will heat red hot. The iron under the knife prevents the flame striking the blade and heating it unevenly, in spots, as it were. When the blade is red hot plunge it into a bath made of linseed oil. Take it out of the oil and polish it. Use the piece of iron the blade was heated on to draw the temper. This hot iron is put on the anvil, the back of the knife edgewise is placed on the iron and moved forward and backward to insure a uniform heat. As soon as the straw colour appears take out any buckle or bend caused by the hardening. Place the other side of the blade on the anvil. A few quick, sharp blows with the peen of the hammer will straighten the blade. Continue the tempering until the purple colour shows. The blade should be tempered so that a very smooth, sharp file will just cut it when rubbed over the surface. Place the blade in the handle and rivet it in place, polish it, and then grind.