EM 862 – War Department Education Manual
CHAPTER XVIII – BLACKSMITHING EQUIPMENT; FORGE FIRES
Whether a farmer can afford a forge and anvil will depend upon the distance to a blacksmith shop, the amount of machinery repair work he needs to do or have done, and his ability as a mechanic. Although not every farmer can profitably own blacksmithing equipment, many farmers can. If a farmer cannot, he should remember that a great deal of repair work can be done with cold metal, if he has a few simple tools like a vise, a hack saw, files, cold chisels, and drills.
Although blacksmithing under many conditions should occupy a minor place in a farm shop course, no such course can be considered complete without at least some instruction in this work. Blacksmithing is generally more difficult than woodwork. Almost any high school boy with average mechanical ability, however, can soon learn to do simple blacksmithing and feel well repaid for his efforts, if he will set himself diligently to the task. In all mechanical work, much more rapid and satisfactory progress can be made if the student will carefully study the theory and principles along with his practice. This is particularly true of blacksmithing.
276. The Forge.-The forge for the farm shop should have a gear driven blower operated by a crank, and it should have a hearth at least 18 in. wide, preferably somewhat larger. Probably the cheapest way of providing a good forge is to buy a good blower and tuyere (that part in the bottom of the hearth through which the blast comes) and make a hearth and stand of concrete, brick, or other masonry. The forge should be provided with a hood and pipe connection for taking away the smoke.
277. The Anvil.-Anvils are of two general grades: cast iron and steel. Steel anvils are much better and should be used if they can be afforded, The two kinds can be distinguished by striking with a hammer. A cast anvil has a dead sound while a steel one has a clear ring.
Anvils are commonly available in sizes ranging from 50 to 200 lb. An anvil weighing 100 or 125 lb. would be quite satisfactory for the average farm shop. A piece of railroad iron 20 to 30 in. long, mounted on a suitable block or stand, will serve fairly well for light hammering and riveting, although a much greater variety of work can be done on a regular anvil.
Use of Different Parts of Anvil.— The horn of the anvil is used for making bends and shaping curved pieces; and the flat face is used for general hammering. The flat depressed surface near the horn is the chipping block, and here all cutting with cold chisels and similar tools should be done, rather than on the face of the anvil. The chipping block is soft and will not damage the chisel if it cuts through. The face is hardened and cutting into it with a chisel would damage both the chisel and the face, which should be kept smooth for good blacksmithing.
The better anvils have a comer of the face next to the horn slightly rounded, so that sharp bends may be made in rods and bars without unduly marring or galling the iron. The round hole in the face of the anvil is used for punching holes. It is called the pritchel hole, taking its name from the sharp punch used by smiths in punching nail holes in horseshoes. The square hole in the face is called the hardy hole and is used for holding the hardy and other tools, such as swages and fullers.
The anvil should be mounted on a solid block and at such a height that the face of the anvil can just be reached with the knuckles of the clenched fist when standing erect.
Mounting the Anvil. — The anvil should be mounted on a solid block, preferably of wood. It should be so located in front of the forge that the workman can take the irons from the fire and place them on the anvil by making a short turn and without the necessity of taking even a full step. The horn should be to the workman’s left (unless he is left-handed, in which case it should be to his right). The face of the anvil should be at such a height that it can be touched with the knuckles of the clenched fist when standing erect and swinging the arm straight down.
278. Tongs.-At least one or two pairs of tongs will be needed. Various types are available, but the hollow-bit, curved-lip bolt tongs are probably the most useful. Flat bars as well as round rods and bolts can be held in them, and the curved part back of the tip makes it possible to reshape them easily to fit different sizes of stock. By grinding, filing, or sawing a groove crosswise in each of the lips, the tongs can be made to hold links practically as well as regular link tongs (see Fig. 245). Tongs 18 to 20 in. long are a good size for average work.
Fig. 245.-Types of tongs. (A). Flat-jawed hollow-bit tongs. (B). Hollow-bit curved-lip tongs. This style is very good for the farm shop. Flat bars as well as round rods and bolts can be held in them.
279. Hammers.-A blacksmith’s hand hammer weighing 1 1/2 or 2 lb. and another weighing 3 or 3 1/2 lb. will handle all ordinary work very satisfactorily.
280. Hardy, Chisels, Punches.-There should be a hardy to fit the hole in the anvil, and there should be a fair assortment of hand cold chisels and punches. The chisels and punches may be made in the shop. If considerable blacksmithing is to be done, it would be well to have a hot cutter and a cold cutter (simply large chisels with handles on them) for heavy cutting with a sledge hammer. It would be well, also to have one or two large punches with handles on them for punching holes in hot metal. Punches for making holes 3/8 in. and 1/2 in. in diameter are probably most useful.
281. Vise.-One vise can well serve for all metal work in the farm shop, including blacksmithing if it is heavy and strong enough. A heavy blacksmith’s steel-leg vise with jaws 4 to 5 in. wide is generally preferred as an all-purpose vise in the farm shop. A leg vise is one that has one leg extending down to be anchored or fastened into the floor. Such a vise can be used for heavy hammering and bending better than other types. If there is a strong steel machinist’s box vise in the shop, it can be used for blacksmithing work if care is used not to do too heavy hammering or bending with it.
Fig. 246.-A heavy blacksmith’s steel-leg vise is a good type of vise for the farm shop.
282. Fire Tools.-A small shovel and poker or rake will be needed for use on the forge fire. These can easily be made in the shop. A flat piece of heavy sheet iron about 3 or 4 in. wide by 4 or 5 in. long, riveted to a bar or rod for a handle, makes a good shovel. A 1/2-in. round rod,with an oblong eye in one end to serve as a handle and the other end flattened and curved, makes a good combination poker and rake.
283. Measuring Tools.-Some kind of metal rule will be needed for measuring and checking pieces being forged. A small steel square is very good for both measuring lengths and checking angles and bends. A wooden rule should not be used to measure hot iron. A caliper, or a caliper rule, for measuring diameter of rods and thickness of parts, although not a necessity, will be found very convenient.
Fig. 248.-Metal measuring tools should be used in blacksmithing. (A). The small steel square is very useful for checking bends and angles as well as for measuring. (B). The caliper rule is especially good for measuring the diameter or thickness of bolts, rods, and bars; as well as for general measuring.
A good forge fire has three characteristics. It is clean, that is, free from clinkers, cinders, etc. It is deep, with a big center of live burning coke. And it is compact, being well-banked with dampened coal.
284. Fuel for the Forge Fire.-Blacksmithing coal is used in the forge. It is a high-quality soft coal that is practically free from sulphur, phosphorus, and other objectionable impurities. When dampened and packed down around the fire, it readily cakes and changes to coke, which is a lightweight material that burns with a clean, intense flame. Ordinary stove or furnace coal will not work satisfactorily in a forge.
285. Building the Fire.-To start a fire, first clean the fire bowl with the hands, pushing all coal and coke back on the hearth and throwing out all clinkers. Clinkers are heavy and metallic and have sharp, hard corners or projections and are therefore easily distinguished from the coke, which is light in weight and easily crumbled. Fine cinders and ashes are easily shaken through the grate into the ashpit.
After cleaning the fire bowl, dump the ashpit below the tuyere and then try the blower and make sure a good strong blast comes through. Sometimes ashes work back into the blower pipe and obstruct the blast.
Fig. 249.-The forge fire should be cleaned by pushing the shovel along the bottom of the hearth to the center of the fire, as at A, and then lifting it straight up, as at B. The clinker and ashes, if any, will be exposed and can be easily removed.
Next light a small handful of shavings or kindling from the bottom and drop onto the tuyere. Give the blower a gentle turn and rake fuel, preferably coke left from the previous fire, onto the burning kindling. Once the fire is burning well, rake more coke onto it, and bank the fire on both sides and on the back with dampened coal. This forms a mound with burning coke at the center, and the heat is concentrated in the center by the dampened coal on the outside. In a little while this dampened coal, sometimes called green coal, has gases driven off and it changes to coke.
286. Maintaining the Fire.-When the coke at the center of the fire burns up, additional coke from the hearth or the underside of the mound is forced into the center, and from time to time green coal is added to the outer parts of the mound to keep the fire well banked. Do Dot continually poke at the fire; simply keep the center well supplied with coke and the outside packed down with dampened coal.
If the fire tends to spread too much or becomes open and loose, throw or sprinkle water on the edges and pack it down with the shovel. Only a gentle blast of air should be used. Excessive air makes an oxidizing fire and causes the iron to scale badly.
287. Cleaning the Fire.-From time to time-usually every half hour when welding-the clinkers and cinders that accumulate over the tuyere should be removed. This can be done by passing the shovel along the bottom of the hearth to the center of the fire and then raising it straight up through the fire. The clinkers can then be easily seen and removed. Most of them will stay on the shovel. The burning coke is then raked back into the center and the outside packed down, using green coal on the outer edges if needed.
Fig. 250.-In heating irons in the forge, they should be placed level-never pointed down. There should be burning coke below them, on top of them, and on all sides of them.
288. Heating the Irons.-To heat irons in a forge, they should be placed in the fire in a horizontal position, not pointing down. There should be burning coke below the irons, on both sides of them, and on top of them. Irons heated in a deep, compact fire heat much more rapidly and oxidize or scale off less than when heated in a shallow, burned-out fire. Some scale will form in spite of a good fire, but it should be kept to a minimum. A good blacksmith keeps the scale brushed from the face of the anvil with his hands.
Small thin parts heat much more rapidly than heavier and thicker parts. To prevent burning the thinner parts, they may be pushed on through the fire to a cooler place, or the position of the irons otherwise changed to make all parts heat uniformly. Mild steel should be heated to a good, bright-red heat for forging. It should not be allowed to get white hot and sparkle, as it is then burning.
289. Fitting Tongs; Holding the Work.-If tongs cannot be found to fit the work, a pair should be reshaped by heating and hammering the jaws over the piece to be held. Poorly fitting tongs are a source of continual trouble and should not be used.
Fig. 251.-By careful planning, many blacksmithing jobs can be done almost, if not altogether, without the use of tongs.
Some Work Done without Tongs.-A considerable amount of work can be done without tongs. An eyebolt, for instance, can be made on the end of a rod 20 or 30 in. long and then cut off when finished.
277. (a) What different kinds of anvils are available? (b) What kind is best, and how may the different kinds be readily distinguished? (c) What size of anvil is best for the farm shop? (d) Can a piece of railroad iron or rail be used satisfactorily in the farm shop? (e) What is the chipping block and what is it for? (f) Why is one corner of the anvil face rounded? (g) What is the purpose of the holes in the face? (h) In what position should the anvil be mounted with respect to the forge? (i) How high should it be mounted?
278. (a) What kind or kinds of tongs would you recommend for the farm shop? (b) What size?
279. What sizes of hand hammers would you recommend for blacksmithing?
280. What other tools, like hardies, chisels, and punches, would be needed?
281. What kind and type of vise is best for blacksmithing?
282. (a) What fire tools -will be needed? (b) What materials would be needed to make these in the shop? I
283. (a) What measuring tools would you recommend for blacksmithing? (b) In what respects is a small steel square better than a rule? (c) Why are wooden rules not satisfactory?
284. (a) What are the characteristics of a good forge fire? (b) What kind of fuel is used in the forge? (c) What are its characteristics or properties?
285. (a) Just how would you go about building a fire in a forge? (b) Why should the fire be well banked with green coal?
286. (a) What attention should the fire have to keep it in good condition? (b) How may it be kept from spreading or becoming open and loose?
287. (a) How often should the fire be cleaned? (b) Just how is the fire cleaned?
288. (a) Just how should the irons be placed in the fire? Why? (b) How may light or thin parts be kept from overheating? (c) How hot should irons be heated for forging?
289. (a) How may tongs be reshaped to fit the work? (b) Under what conditions may work be done without tongs?
RADEBAUGH: “Repairing Farm Machinery.”
FRIESE: “Farm Blacksmithing.”
HARCOURT: “Elementary Forge Practice.”
Boss, DENT, and WRITE: “Mechanical Training.”
CHAPTER XIX – FUNDAMENTAL FORGING OPERATIONS
Forging may be defined as changing the shape of a piece of metal by heating and hammering. All the various operations that a blacksmith performs in forging iron may be classified into a surprisingly small number of fundamental or basic processes. Once these are mastered, the beginner is well on his way to success, and he can do practically any ordinary piece of forge work. These fundamental operations are (1) bending and straightening; (2) drawing, or making a piece longer and thinner; (3) upsetting, the opposite of drawing, or making a piece shorter and thicker; (4) twisting; and (5) punching. Other operations commonly done by a blacksmith, but which are not strictly forging, are welding, tempering, drilling, threading, filing, etc.290. Bending and Straightening.–In bending at the anvil, two things are most important:
1. Heat the iron to a good bright-red heat, almost but not quite white hot, throughout the section to be bent.2. Use bending or leverage blows-not mashing blows.
The iron should be so placed on the anvil and so struck that it can bend down under the hammer blow without being forced against the anvil and mashed. If the iron is struck at a place where it is resting firmly on the anvil, it will be mashed instead of bent. A few moderately sharp blows are better than several lighter blows.
Abrupt square bends can be made over the face of the anvil near the chipping block where the corner of the anvil is rounded to prevent marring or galling the iron.
Care should be taken to keep the iron at the proper bending heat. If it gets below a red heat, it should be put back in the fire and heated again. To bend a piece at a certain point, without bending the adjacent section, the piece may be heated to a high red heat and then quickly cooled up to the point of bending by dipping in water. Bending is then done quickly by hammering, or other suitable methods.
Bending may be accomplished in several ways besides hammering over the anvil. The iron may be heated and then put in the pritchel or hardy hole and bent by pulling; or it may be clamped in a vise and bent.
Straightening can usually best be done on the face of the anvil. The stock should always be firmly held and then struck with the hammer at points where it does not touch the face. Sighting is the best way to test for straightness and to locate the high points that need striking.
Fig. 252.-To make a uniform bend in the end of a rod, strike the Part that projects beyond the horn and keep feeding the rod forward with the tongs as the bending progresses. Keep the iron at a good working heat and do not strike the rod where it rests on the horn.
Bending Flat Bars Edgeways.-A flat bar can usually be easily bent edgeways by heating and placing over the horn and bending the two ends down slowly, using the hands if the piece is long enough, or two pairs of tongs in the case of short pieces (see Fig. 253). Sometimes the bending can be done easily by putting one end of the piece in the hardy hole and pulling on the other end (see Fig. 254). If the stock starts to buckle, it should be laid flat on the anvil and straightened. Hammering the outside edge of the iron when laid flat will tend to stretch it and therefore help with the beading. Once the bend is well started, hammering the piece on edge around the horn is not so difficult. The stock should always be firmly held, either by hands or with tongs, and the parts to be bent should be at a high red heat. Places not to be bent should be comparatively cold.
Fig. 253.-Flat iron may be bent edgewise by heating to nearly a white heat and bending slowly with tongs. This method is good in making flat chain hooks.
Fig. 254.-Bending of heavy pieces can sometimes be best accomplished in the hardy hole.
291. Bending and Forming an Eye.-One of the most common bending jobs in the blacksmith shop is that of forming an eye on the end of a rod. The following is a good method of making such an eye:
1. Heat the rod to a good red heat back for a distance of about 5 to 8 in., depending on the size of the eye.2. Quickly place the rod across the face of the anvil with just enough of the heated end projecting beyond the edge of the anvil to form the eye. For exact work the length of hot iron that is to project over may be quickly measured with a metal rule. The iron should be placed across the anvil well up near the horn where the edge is rounded.
3. Bend the end down, forming a square bend, with a few well-directed blows. Work rapidly before the iron cools.
4. Heat the end of the stock and start bending the. tip end around the horn. Work from the tip back toward the stem. Keep the iron hot throughout the part being bent; otherwise the bending will be slow and difficult, and the iron will not bend at just the places desired. If the square bend at the juncture of the stem and eye tends to straighten out, it is an indication that the end of the stock is not being kept hot enough while being bent.
5. Round the eye by driving it back over the point of the horn, noting carefully where it does not rest against the horn and striking down lightly in these places. Keep the iron well heated.
6. Center the eye on the stem, if necessary, by placing the stem flat on the anvil face with the eye projecting over the edge, and striking the. eye. The stock should be well heated at the juncture of the stem and eye, but the eye itself should be practically cold. Such a condition can be produced by heating the whole eye and then quickly cooling most of the rounded part by dipping in water.
292. Drawing.-Drawing is the process of making a piece longer and thinner. Two important points should be kept in mind while drawing:
1. The iron must be kept at a good forging heat, a high red or nearly white.2. Heavy, straight-down, square blows should be struck.
Many beginners make the mistake of striking a combination down-and-forward pushing blow, thinking that the pushing helps to stretch the metal.
A. Place a well-heated iron across the anvil with. enough stock projecting over -to form the eye. Where the eye must be made accurately to size, use a metal rule or square for measuring. Work rapidly. I
B. Bend the projecting portion down, forming a right angle.
C. Finish the right angle bend by striking alternately on top and on the side, keeping the iron at a good working heat all the while.
D. Start bending the tip end around the horn, being careful to strike “overhanging” or bending blows.
E. Gradually work back from the end to the square bend.F. Turn the eye over and close it up. Exert considerable back pull on the tongs to keep the upper part of the eye up off the horn. In this position the hammer can strike bending blows instead of flattening or mashing blows.
G. Round the eye by driving it back over the point of the horn. Carefully note where the eye does not touch the horn, and strike down lightly in these places.
H. To straighten the stem of an eye, place it across the corner of the anvil face and strike the high points while the iron is at a good working heat.
Drawing can be done more rapidly over the horn than on the face of the anvil, as the round horn wedges up into the metal and lengthens it, and there is less tendency for it to stretch in all directions. If a piece tends to get too wide it may be placed on edge and hammered.
Hammering after the red heat leaves is hard work and accomplishes little. Also, the iron is apt to split or crack if hammered too cold.
Drawing Round Rods.-To make a round rod smaller, the following steps should be carefully followed.
1. Make it four-sided, or square in cross section.2. Draw it to approximately the desired size while it is square.
3. Make it distinctly eight-sided by hammering on the corners after it is drawn sufficiently.
4. Make it round again by rolling it slowly on the anvil and hammering rapidly with light blows or taps.
An attempt to draw round rods without first going to the square section not only requires a lot of extra work but usually results in a badly distorted and misshaped piece.
Pointing a Rod.-If a round point is desired on a rod, a square tapered point should first be made. It is then easy to make it eight-sided and finally round.