Part 12

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, 2-1/2 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 2-1/2 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 1-1/2-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 1-1/4 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 1-1/8 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 1-5/8 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 1-1/8-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 1-3/4-in. taper on the other. (See drawing.)

_Set hammer:_ A set hammer is made with a piece of 1-1/8-in. square steel; 1-5/8 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 1-1/4 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 2-3/4 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:_ 1-1/4 × 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, 1-1/2 × 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 1-1/2-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 1-1/4 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.