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We are glad to show in this way our apprecia- tion of your courtesy in giving us the names of your friends, all of whom are likely to become regular purchasers of our books. We promise that your name will not be mentioned in our correspond- ence with them, so don't hesitate to send the coupon on that account. OXY-ACETYLENE WELDING PRACTICE A PRACTICAL PRESENTATION OF THE MODERN PROCESSES OF WELDING, CUTTING, AND LEAD BURNING, WITH SPECIAL ATTENTION TO WELDING TECHNIQUE FOR STEEL, CAST IRON, ALUMINUM, COPPER, AND BRASS BY ROBERT J. KEHL, M.E. M CONSULTING MECHANICAL ENGINEER, CHICAGO AMERICAN SOCIETY OF MECHANICAL ENGINEERS ASSOCIATE, AMERICAN INSTITUTE OF ELECTRICAL ENGINEERS ILLUSTRATED AMERICAN TECHNICAL SOCIETY CHICAGO 1918 COPYRIGHT, 1917, BY AMERICAN TECHNICAL SOCIETY COPYRIGHTED IN GREAT BRITAIN ALL RIGHTS RESERVED - v1$0"H, INTRODUCTION HIGH-TEMPERATURE flames, such as the oxy-hydrogen flame, were known for many years, but the oxy-acetylene flame was first used experimentally in 1901 by Fouche and Picard. The same experimenters also developed the first welding blowpipes, used industrially in 1903, and started the developments in oxy-acetylene welding which were destined to become so important in the modern manufacturing and repair fields. Cutting by means of oxygen was first made commercially possible in 1905 by Jottrand, who took out his basic patent in that year. an( J buckling of the shell. Tubes and Pipes. Various tube and pipe welds are given in Fig. 66. The methods for closing the end of a pipe with a head are shown in Fig. 67. The first is the easier and stronger of the two. ILD. L Fig. 68. Welds for Pipe Flanges Three methods of welding flanges to pipe are shown in Fig. 68. Hie first method is easier to weld than the second; but the latter OXY-ACETYLENE WELDING 57 Fig. 69. Preparation of Heavy Forgings for Welding is the stronger. The third method is the best method of welding flanges to pipe, but is, of course, a special type of flange. Welding Heavy Steel Forgings and Steel Castings Preparation. In welding heavy steel sections, such as crank- shafts, axles, and the like, the weld is prepared by grooving or beveling from both sides. This is done because it is easier for the oper- ator to do the work and for the sake of economy, because by beveling from both sides less filling material is necessary and, consequently, less time and gas are needed. Square Sections. Square or rectangular sections of forgings are best prepared by beveling half way through from each side, Fig. 69. After the welding has been carried on from one side, the piece turned over and the welding completed from the second side, there will probably be a slight bow, or curve. In the case of forgings, Fig. 70. this is not objectionable, be- cause the work can be, and, in fact, should be, reheated and straight- ened. The reheating in the case of forgings is beneficial to the grain of the material and the strength of the weld. With castings, however, this bend- ing is not possible. There- fore, to keep the work in alignment, it is best to pre- pare the work as shown in Fig. 70. The welding is carried on two- thirds of the way through from the first side, and then finished by turning over and working from the second side. Round Sections. Round or elliptical sections should be prepared by beveling the ends to a wedge as indicated in Fig. 71. They should never be turned down to a point. By preparing the pieces as shown Preparation of Heavy Castings for Welding Fig. 71. Preparation of Round Sections for Welding 58 OXY-ACETYLENE WELDING in the illustration, the welder will have a flat surface to build his weld upon. If the work were prepared to a point, the filling material when added would have no surface to lie upon and would run down in drops, necessitating burning or melting away when the work is turned over, and probably resulting in a weak weld with con- siderable oxide. Expansion and Contraction. Expansion and contraction will probably cause very little trouble to the operator in the case of shafts and other heavy pieces that are not connected. The only difficulty the operator will encounter in these cases will be the possible bending, which was noted above, when welding from two sides. However, if the broken part is confined by rigid members, the work should be handled either by pre-heating, or one of. the other methods recommended and ex- plained under Expan- sion and Contraction, pages 36 to 40. V-Blocks. When welding shafts, it is ad- visable to line them up in position on V-blocks, so that they may be turned over and still kept in Fig. 72. "V Blocks for Welding shaft. alignment, Fig. 72. Welding Heavy Section. In the case of a heavy section select the proper size welding head and a piece of welding rod of the cor- rect analysis for the particular work at hand, and place the work in alignment. , If the section is over or about one inch, it should be pre-heated by means of a gas or oil burner until it is at a red heat. This will save oxygen and acetylene, and will bring the material to a tempera- ture at which it will be more receptive to the action of the welding flame and thereby insure a more homogeneous weld. If not objec- tionable to the operator, it is advisable to let the pre-heating burner play on the work while the welding operation is going on, taking care, of course, that the materials of combustion of the pre-heating burner do not strike the molten metal and have a detrimental effect on the weld. OXY-ACETYLENE WELDING 59 The welding flame is first played on the edges at the bottom of the groove until they are in a molten condition. The flame is then momentarily withdrawn to allow them to flow together and "set", and form the bottom of the weld. When a perfect union of the bottom is secured all the way across, the welding rod is brought into use. By playing the flame around the welding rod and the edges of the weld instead of directly on the welding rod, it is possible to bring them to a fusing temperature at the same time. The rod is then gradually added to the weld, layer by layer, until the entire groove has been filled up. The welding rod is kept plunged into the molten metal all the time to prevent oxidation. Any oxide that forms during the welding is floated to the top and removed by scraping with the welding rod, or by blowing away with the force of the welding flame. The welder must be careful that he does not allow the molten metal to run over the sides of the weld. Each layer is added in such a way that it extends slightly beyond the end of the groove. Then, from time to time, as the groove is filled up, the operator smooths down the two ends. Hammering. As each section, about \ inch thick, is added to the groove, the operator stops the welding operation, heats the work to a bright yellow, and hammers the weld lightly but rapidly to give it as fine a grain as possible. After the weld has been com- pleted, it is either hammered or annealed, as directed on page 45. CAST-IRON WELDING General Considerations. Many defects are experienced by the beginner in welding cast iron because of its peculiar properties. The two principal faults noticed are the production of hard, glassy, and brittle metal in the weld, and subsequent cracks, breaks, and checks either in the weld or in the adjacent metal, owing to excessive internal strains set up by unequal contraction. Both are serious defects, and the liability of their occurrence is so great that proper preventive methods should be continually borne in mind and applied while welding this material. Oxidation. Cast iron melts at about 2000 to 2190 F., and iron oxide melts at about 2450 F. The oxide is formed, however, at low temperatures, a bright red heat being sufficient to cause the combination of oxygen from the air with the iron of the casting. 60 OXY-ACETYLENE WELDING It is not possible to melt this oxide and flow it from the weld, so it remains in the casting in the form of thin flakes or crust. This not only prevents the alloying of the molten metal, but also combines with the free carbon and is, consequently, conducive to the formation of white iron. Therefore, this oxide must be removed or destroyed. Expansion and Contraction. Cast iron is absolutely lacking in elasticity, and its tensile strength is very low. In preparing work for welding, it is always necessary to take fullest precautions against the bad effects of expansion and contraction. Expansion and con- traction should be treated with more importance in the welding of cast iron than in any other metal. When the internal strain produced by contraction is greater than the tensile strength of the section to which it is confined, fail- ure will occur. When the strain is not great, but still exists, the resistance of the section to external stresses is reduced in proportion. Thus a casting may appear to be normal after welding but the excessive internal strains caused by the welding may make it fail at the slightest shock. One of the three general methods of coping with the forces of expansion and contraction, which are given on pages 36 to 40, must be used when welding cast iron. The proper method to pursue is determined by the size and shape of the casting and the nature and location of the break. A very large percentage of the failures due to shrinkage cracks may be prevented by an intelligent anticipa- tion of the forces of expansion and contraction and the proper hand- ling of the work to overcome these. Pre=Heating. Pre-heating should be used to some extent in all cast-iron welding. If the piece is small and the break is so located that it is not necessary to consider expansion and contraction, the blowpipe should be played upon it until the chill is removed from the casting. If the casting is large, an oil or gas burner, or charcoal fire can be used. In a large casting this preliminary heat treatment not only favors the execution of a good weld but also requires less oxygen and acetylene because of this large volume of heat from a cheap source, thereby reducing the cost of welding. Welding Rods. The success of cast-iron welding depends greatly upon the selection of a suitable welding rod. It has been proved time and again that hard, brittle, and weak welds have been OXY-ACETYLENE WELDING 61 produced for no other reason than because inferior filling material was used. The presence of silicon in proper proportion tends to produce a soft gray-iron weld. It increases the fluidity of the metal, retards oxidation, and prevents decarbonization and blowholes. The success of the filling rod is dependent upon the amount of this ele- , ment it contains. From 3 to 4 per cent is the average silicon content of good welding rods. The welding rod must be of high-grade cast iron, soundly cast and absolutely homogeneous. It must be free from all sand, grit, and rust. For convenience in handling, it is usually cast in 24-inch lengths of three diameters, J, f, and | inch. In case either a longer or heavier rod is desired, two or more are welded together. Flux. The principal problem that confronts the welder is to prevent the formation of oxide, and in case it is formed, to reduce it and remove it from the weld. If this is not done, the molten metal will be enclosed in a thin film of nonmetallic material, and any additional metal that may be fused or added will adhere to this film rather than break through it and fuse homogeneously with the other metal. It is not possible to satisfactorily break up this film mechanically, therefore it must be reduced to a molten, or slag, condition. To accomplish this a suitable flux is used that will dissolve the oxide. A flux is not used solely to dissolve the oxide, but also to float off other impurities, such as sand, scale, and dirt. It forms a protecting glaze on the weld and surrounding surfaces and increases the fluidity of the molten metal. Borax and salt (sodium chloride) are two compounds often used by welders, but they really contain little merit as a flux. Their low fusibility seems to be the only point in favor of their use. Occasionally, they may be employed to advantage in welding heavy sections or burned iron, such as are found in firebox and grate cast- ings, but their function is only that of a cleanser. Both tend to produce hard iron. There are certain flux powders put on the market that contain large proportions of manganese. These powders cannot help but have a hardening effect on the iron. Others contain potas- sium perchlorate, a violent oxidizing agent. Still others contain material that chlorinize the weld. Needless to say, powders of this 62 OXY-ACETYLENE WELDING kind must not be used. It is best to guard against the purchase of such defective mixtures by obtaining flux powders from reliable sources. It is necessary that the welder learn to apply flux properly. An excess will cause as much trouble as an insufficient quantity. Blowholes may be increased in size and number by using too much flux. Also the molten iron will incorporate certain constituents of the flux if it is applied in excess. The amount to be applied depends upon the flux used. A welder must learn to know his flux as well as his blowpipe. The powder should be applied regularly by dipping the hot welding rod into it. The quantity adhering is sufficient. Do not throw large quantites into the weld as plenty will be added by the welding rod. Preparation of Welds. All cast iron over J inch in thickness should be beveled or chamfered before welding. If this is not done, it is necessary that the metal be burned out by the blowpipe in order that complete penetration be assured. This is bad practice as it is almost impossible to do it without either changing the state of the metal in the groove due to the forced flame, or causing partial ad- hesion. The chamfering should be a little wider than on other metals for the reason that it is good practice to introduce as much special metal from the welding rod as possible. The chamfering can be done by various means. If the casting is light and broken in two pieces, it may be taken to an emery wheel and the edges ground off. If the casting is too heavy to move, a portable grinder or cold chisel and air or hand hammer can be used. If the casting is only cracked, the cold chisel and air or hand hammer are the most satisfactory tools to use. After the weld has been beveled satisfactorily, the adjacent metals should be cleaned about \ to \ inch from the edge. This is important, because all dust, sand, scale, etc., should be removed from the welding zone. To Prevent Crack from Extending. If the defect in a casting is a crack that shows a tendency to extend upon heating, a hole should be drilled in the casting a short distance from the end and in the direction the crack would follow. The crack will not extend beyond this hole, and the hole can be very easily filled in. OXY-ACETYLENE WELDING 63 Welding Process. Although the melting point of cast iron is not high, the total heat required to bring it to fusion is great, therefore a blowpipe of large size is used. The speed of welding is increased considerably, and the selection of the proper size blow- pipe is influenced by the extent of the pre-heating. Cast iron melts very rapidly after the fusing point is once reached, and when molten is extremely fluid. Because of this property, the welding should be carried on horizontally, otherwise the metal will flow toward the lowest point. This is not desired, because it will tend to produce adhesion. In case it is not possible to arrange the casting so that the weld will be horizontal, the welding must be started at the lower end, and skill must be used to prevent the too rapid advance of the molten metal. It is very difficult to produce vertical and overhead welds because of the fluidity. In welding thin sections of cast iron, the rapidity with which it melts and its fluidity often cause the metal to sink, bulge downward, or drop in. Consequently, it is necessary that close observation and careful manipulation be used on this kind of work. Flame. The incandescent jet of the oxy-acetylene flame should never impinge on the molten metal. The tip of this jet should be held at a distance of f to J inch from the metal according to the thickness. The molten iron is seriously influenced by the high temperature of this jet and may become oxidized and decarbonized. This must be rigidly observed except when it is necessary to use the jet to burn out sand holes, blowholes, etc. Manipulation of Blowpipes and Welding Rods. Because cast iron fuses rapidly when once the melting point is approached and the molten iron is extremely fluid, the circular or oscillating motion imparted to the blowpipe need not be so pronounced. The welding of cast iron is nothing but a succession of overlapping miniature pools, or puddles, of molten metal. The weld is started by playing the blowpipe on the two lower edges of the weld. The flame should strike the weld almost perpen- dicularly, because if the blowpipe is inclined, the flame will blow the molten metal ahead of the weld, and adhesion will result. When at the proper temperature, these edges are fused together without any filling material by the aid of a little flux. It is important that this first operation be carefully carried out, as the strength of 64 OXY-ACETYLENE WELDING the weld is dependent upon a good bottom and top. When this first fusion has been successfully obtained, the welding rod is brought into play and the high silicon metal is added. With each addition, Fig. 73. Warm Welding Rod Is Dipped into the Flux before Each Addition to the Weld Fig. 74. For Cast-Iron Welding, Blow- pipe and Welding Rod Are Held Almost Vertical the welding rod is previously dipped into the flux can, and the adhering flux introduced in the weld, Fig. 73. As the welding of cast iron is a comparatively rapid procedure, the welding rod can Fig. 75. Dirt May Be Scraped off by Means of the Welding Rod Fig. 76. Welding Rod Should Not Be Held Too Far from Welding Zone. be held more vertically and added faster, Fig. 74. In welding "dirty" iron it is sometimes convenient to hold the rod in a horizontal position and scrape out sand, carbon, or any other dirt by means of the rod OXY-ACETYLENE WELDING 65 as soon as it appears, Fig. 75. In this connection, it may be added that the welding rod should be used constantly to work out impurities and blowholes. The welding rod should be melted as much as possible in the molten metal of the weld. It should be plunged into this liquid, and the fusion carried out by playing the flame around it. The welding rod should not be held too far from the welding zone, Fig. 76, nor should it be added to the weld drop by drop as shown in Fig. 77. As a section of the weld is finished, it should be scraped or rubbed with a file while red hot, Fig. 78, to remove the film of flux, scale, sand, and dust that is present. This film if allowed to cool becomes very hard and is quite resistant to machine tools. Regardless of the Fig. 77. Welding-Rod Should Not Be Fig. 78. Scraping Finished Weld with File to Added Drop by Drop Remove Scale quality of metal beneath it, many welds have been rejected because of the hardness of this superficial surface. If the weld is carefully executed and the surface is cleaned, it will look like the left of Fig. 79, while if poorly executed and not cleaned, it will look like the right of Fig. 79. Never go over a weld the second time if it can be avoided. In case it is absolutely necessary, always add fresh metal from the welding rod, as a failure to do this will cause a loss of silicon in the weld and destroy its value to the metal. Always perform the welding as fast as possible, because extended heating will tend to lower the silicon content of the weld, with the resultant formation of hard iron. 66 OXY-ACETYLENE WELDING Blowholes. Blowholes occur frequently in the weld and are particularly troublesome if in the bottom of the weld. Their presence can be caused by mechanically enclosed gases or by improper blow- pipe handling. When blowholes appear in the weld, they should be instantly worked out. This may be done by forcing with the welding rod and applying flux. In beginning a weld, it is necessary that the presence of blowholes be guarded against, as it is difficult to work out a blowhole at the bottom of the weld after it is finished. Occasion- ally, in going over a weld, a blowhole is discovered; this must first be Fig. 79. Appearance of Cast-Iron Welds That Have Been Properly (left) and Poorly (right) Executed burned out by the white jet of the flame and then worked over with the welding rod. After- Treatment. The rate of cooling materially influences the structure of the metal in the weld. If rapid cooling is allowed, hard brittle iron is produced. If slow cooling is employed, soft gray iron is formed. Internal strains and stresses may be distributed and adjusted or, in some cases, eliminated by proper cooling and annealing. Castings which are not large or which it has not been necessary to pre-heat extensively may be satisfactorily annealed by playing the blowpipe on the weld and surrounding metal until it is at a bright red heat. The heated portion is then covered with asbestos OXY-ACETYLENE WELDING 67 paper, cinders, or other nonconducting material that will retain the heat and protect the castings from air currents. For small castings, a barrel or bin of hydrated lime and fiber asbestos is recom- mended. This makes a convenient arrangement and is very satis- factory as an annealing agent. Where it is necessary to heat the entire casting in a charcoal or coke fire, the same temporary furnace used for pre-heating may be used in annealing. After the welding has been completed, the casting should be covered over with hot coals and ashes, and the furnace should be bricked up, i. e., all large air ports closed, the top covered with asbestos paper, and the casting allowed to cool with the fire. The castings should never be removed from the annealing fire until they are entirely cold. This is imperative, as cold air currents on the warm castings may cause checks or cracks. In some cases, 12 to 24 hours are required for satisfactory cooling. Use of Carbon Blocks. In case it is not possible to line up the weld horizontally, or it is necessary to fill in a wide hole, carbon blocks or steel plates are sometimes used to dam or retard the flow of the metal. MALLEABLE-IRON WELDING Malleable Iron. Malleable cast iron, or malleable iron, as it is commonly called, is used extensively in castings where toughness, malleability, and resistance to sudden shock are required. The characteristic that gives malleable iron its greatest value as compared to gray iron is its ability to resist shocks. Malleability in a light casting, J inch thick and less, means a soft pliable condition and the ability to withstand considerable distortion without fracture, while in the heavy section, J inch and over, it means the ability to resist shock without bending or breaking. In the manufacture of malleable-iron parts, white iron castings are packed in annealing pots with suitable material, such as mill- scale, borings, etc., and subjected to a cherry red heat for from 48 to 96 hours, after which they are allowed to cool slowly. During this annealing process, the material in which the castings are packed absorbs the carbon from the surface of the casting. In this way the surface becomes really a steel, while the inside, or core, becomes gray cast iron. 68 OXY-ACETYLENE WELDING Fusion Weld Not Possible. When malleable iron is heated to a fusing heat the malleable properties are destroyed and cannot be regained. Brazing Malleable Iron. The most successful method of joining malleable iron with the oxy-acetylene blowpipe is by brazing with Tobin bronze. While this gives a joint of different color, yet the strength, malleability, and machining qualities are satisfactory. The two pieces to be joined are beveled as for cast-iron welding. The edges are brought to a point just below fusion, great care being taken that they do not become fused. When the edges are at the right temperature, a rod of Tobin bronze is fused into the groove with the aid of a good brass flux. The work should be carried out by using a flame having a slight excess of acetylene and should be done as rapidly as possible to prevent oxidation of the bronze. ALUMINUM WELDING General Considerations. When aluminum approaches its melt- ing point, it does not change color in ordinary light, but retains its silvery appearance even when in the molten condition. When molten, it is very fluid and is, therefore, rather difficult to control under the welding flame. Oxidation. Aluminum oxidizes very easily when in a molten condition, forming an oxide that melts at about 5400 F. The oxide, therefore, cannot be penetrated by means of the flame, but must be removed either chemically by means of a flux or mechanically by means of a paddle. Expansion and Contraction. Because of the high heat con- ductivity of aluminum, expansion and contraction do not give great difficulty owing to localized heating. However, because aluminum expands greatly and is very weak when at high temperatures, con- traction strains are very likely to produce cracks or checks unless the work is allowed to cool evenly and slowly. It is advisable to pre-heat aluminum castings to between 300 and 400 F. to aid the distribution of the heat and prevent warping. Welding Rod. In welding sheet aluminum, such as automobile bodies, the welding rod should be clean material of the same alloy as the sheets that are being welded. If wire cannot be obtained of the same composition as the sheets, narrow strips should be OXY-ACETYLENE WELDING 69 sheared from the sheets themselves and used for a filling material. The strips should be sheared about as wide as the sheets are thick. For aluminum castings, such as crank cases, a good grade of aluminum wire about J inch in diameter should be obtainecj. Welders should not use the cheap solders or very low fusing cast rods that are sometimes sold, and for which great claims are made. The operator will readily appreciate that when these materials are added to the weld they will merely adhere to the sides, because, while the filling material will be quite fluid, the edges of the weld will not be at a fusing temperature. Flux. It is impossible to weld sheet aluminum without the use of a good flux to dissolve the oxide and float it to the top as a slag. In cast-aluminum work a paddle may be used to accomplish this result, but such a device is not practical for sheet work. The flux may be applied either by dipping the warm welding rod into the flux powder or by mixing the flux with water to form a paste and applying this to the joints by means of a brush. Care must be taken that too much flux is not used, because an excess will produce a porous weld and one with a poor surface. After the work has been completed the flux should all be washed off with warm water. Flame. In order to be sure that an oxidizing flame is not being used, it is permissible and advisable to use a flame showing a slight excess of acetylene. This flame will also have the advantages of being slightly larger in volume than the neutral flame and of lower temperature, this last feature being helpful, especially to the new operator. Sheet=Aluminum Welding Sheet-aluminum work may be handled very similarly to sheet steel as regards preparation and allowance for expansion and contraction. Types of Joints. For light sheets under ^ inch the flange weld should be used. The butt joint may be successfully made on light sheets by an experienced operator, but there is a great deal of danger of burning through and having to fill up holes, which will leave a poorly finished weld. For sheets above YS mcn the butt weld is found to be the best, and for sheets above f inch the edges should be beveled the same as for steel plates. 70 OXY-ACETYLENE WELDING Welding Process. Select the proper size blowpipe and welding rod, a good flux, and arrange the work for welding. Start the welding by playing the secondary flame of the blowpipe over the parts surrounding the weld, to warm them up slightly. If the flux is to be applied with a brush, it should be done at this time, because the heat will evaporate the water and leave the solid flux evenly dis- tributed over the weld. Welding should then be started from J to 1 inch from the end not at the end. The blow pipe should be handled about the same as for steel welding, care being taken that the inner cone of the flame does not come in contact with the metal. For very thin sheet welding it is not necessary to give the circular or oscillating motion to the blowpipe; it is merely necessary to move it forward in a straight line. On the heavier work, however, the same motions should be used by the welding operator as are used for steel. The welding wire is best held directly in line with the weld and always in contact with the metal just ahead of the blowpipe. If the wire is not in con- tact with the edges when they become molten, they will be likely to curl up or draw away instead of flowing together. After the main weld has been completed, the operator should go back and weld the short section that was left unwelded at the very beginning. After the work has cooled the flux should be removed by washing off with warm water. Re-Welding. The operator should be careful that the weld is completed as he goes along, so that he will not have to go back to make repairs or to do re-welding. If it is necessary to go back over a weld, cracks or checks are very likely to result because of the weak condition of the metal when it is at a fusing temperature. If it is necessary to re-weld a certain portion of the joint, the surface should be chipped off so as to present a clean surface for the new filling material to fuse to. Following the suggestions already made, the seam and the surrounding surfaces should be thoroughly pre- heated before the welding is started to prevent cracking as much as possible. After- Treatment. If possible, welds in aluminum sheet should be reheated evenly to equalize any internal strains. Then, after the weld has become cold, it should be hammered to improve the grain of the metal. OXY-ACETYLENE WELDING 71 Cast Aluminum Welding Aluminum Castings. Most aluminum castings are alloys of aluminum, zinc, and copper; the alloy being added to the aluminum to give it a higher tensile strength and increase its resistance to shock. The welding of cast aluminum is different from that of sheet aluminum and resembles in a general way the welding of cast iron. Oxidation is taken care of by using flux or by scraping the oxide out by means of a paddle. The second method is faster and is the one preferred by most operators. Paddle. The paddle is made by flattening down the end of a J-inch steel rod to a smooth short flat blade about f inch wide. The handle may be left straight or bent to suit the operator. The paddle should be used only when just below a red heat. If it is cold, the molten metal will stick to it, and if it is too hot it will burn and the metal will stick to the roughened surfaces. Preparation. Sections if over J inch in thickness should be chamfered before the welding is started. Sections thinner than this may be worked without beveling. The old metal may be scraped out by means of the paddle in order to give a clean bright surface for the new material to be added to. Pre=Heating. Because aluminum alloy castings are not very ductile and are weak when at a high temperature, expansion and contraction must be taken care of. This is handled in the same general way as in the case of cast-iron work. The casting should be pre-heated either partially or wholly by some slow heating agent, such as a gas burner or mild charcoal fire. The pre-heating should never be carried to too high a temperature, because of the danger of the metal sinking, or caving in. The casting will be sufficiently warm for welding when a file or chisel will mark it easily, or when a piece of dry pine stick is charred upon being drawn across the heated section. Welding Process. When a flux is used in welding cast alumi- num, the work is carried on in the same general manner as in welding cast iron, and the same general precautions regarding the peculiari- ties of the metal are to be observed as in welding sheet aluminum. If a paddle is used to break the film of oxide and scrape it out of the weld, the edges are brought to a state of fusion for a length of about 1 or 1 J inches. The paddle is then used to scrape out the weld 72 OXY-ACETYLENE WELDING to make a slight bevel and present clean surfaces for the filling mate- rial to be added to. The welding rod is then introduced into this groove. The paddle is used continually to work in the filling material, scrape off any oxide that forms, and then to smooth off the surface of the weld. After a small section of the joint has been completed, the casting is turned over, and the weld for this length is smoothed off on the underside by means of the blowpipe and paddle. The welding is carried on in this manner, section by section, until the entire joint is completed. If the weld were completed on the first side and then turned over and smoothed its entire length on the underside, cracks would develop, and the casting would warp out of shape. After=Treatment. When the welding has been completed, the casting should be reheated slightly to remove any local strains and should then be covered over with asbestos paper to protect it from drafts and to allow it to cool very slowly. If the cooling is carried on rapidly, or if air currents are allowed to strike the casting, it will very likely crack either in the weld or some weak section. COPPER WELDING General Considerations. Because of the high thermal conductivity of copper, the heat from the blowpipe is conducted back into the work rapidly and is lost to the weld. This necessitates the use of a large size welding head or the use of an auxiliary source of heat to assist the welding flame in the case of heavy work. When at high temperatures, copper is weak in tensile strength the same as aluminum. Because of these two factors the effects of expansion and contraction must be carefully considered, so that the work will not cool too rapidly after the welding has been completed, and will not crack at high temperatures. Oxidation. Copper oxidizes quite readily, forming an oxide which dissolves in the molten metal and changes the structure of the weld. The amount of oxide that can be absorbed is very high, consequently great care must be exercised to keep the absorption at a minimum. Welding rods containing a small percentage of phosphorus and suitable fluxes are used to counteract the oxide and reduce it as much as possible. Welding Rod. For successful copper welding, it is necessary to use electrolytic copper containing about one per cent phosphorus, OXY-ACETYLENE WELDING 73 supplied in coils and drawn rods. The cast copper alloy rods that are on the market are not satisfactory, because the structure and composition will vary even in a single rod to such an extent that a homogeneous weld cannot be made. Flux. In welding copper the flux is used not only to cleanse the weld, but also to protect the metal adjacent to the welding zone from the gases of the flame. When welding sheet copper it is advisable to make a paste of the flux by adding water and to coat the metal about one inch adjacent to the edge of the weld. When this flux is melted, it will form a glassy film that will protect the metal from the gases of the flame and the air surrounding the work. Additional flux is added to the weld as the work progresses, by dipping the warm rod into the dry flux, as in welding other materials. Flame. It is very important that the neutral flame be maintained at all times, and the operator should use great care in adjusting his gases, so the flame will not have an excess of acetylene nor be oxidizing. Because of the peculiar properties of the metal, the gases of the reducing flame are very likely to be absorbed, and because of the ease with which the metal oxidizes, oxidation is liable to occur if the flame contains an excess of oxygen. Preparation. Sheets that are less than J inch in thickness may be butted together without beveling. Sheets heavier than this should always be beveled, and no attempt should be made to depend upon the flame to penetrate the heavier thicknesses. In all cases of copper welding, the edges to be joined and the material adjacent to the edges should be scraped or filed to present a clean surface for the filling material to be added to. Welding. The edges of the metal surrounding the weld should be raised to a fairly high temperature before the actual welding is started. On small pieces and light-weight work, this may be done by means of the welding blowpipe, but for heavy work and long welds, it is best to do this by means of a gas or oil pre-heating burner. After the work has been brought to a high temperature, the welding should be started at one end and should be performed as rapidly as possible. The welding rod and edges of the weld should reach the state of fusion at the same time, so as to prevent adhesion and to insure a good weld. This feature is harder to accomplish in welding copper than in other metal, because the heat is conducted back into 74 OXY-ACETYLENE WELDING the rod or into the work very rapidly, necessitating very careful and skillful manipulation of the blowpipe and rod. The blowpipe should be held almost vertical, about the same as in the case of cast-iron welding. If held at too great an angle, the molten metal will be blown ahead and will adhere to the cold edges of the weld in advance of the blowpipe. The inner cone of the flame should never come in contact with the metal, but should be held about J or 1 inch above the surface of the weld to prevent burning the metal. The oscillating motion should be carried on about the same as in steel welding but a little more rapidly, and should consist of smaller circles. The welding rod should be plunged into the molten metal all the time and should be continuously moved around or stirred, so that it will be thoroughly incorporated and will bring the oxide and slag to the surface. The weld should be built up above the surface of the sheets, so there will be enough material to allow for hammering after the welding has been completed.. Re-Welding. In case it is necessary to re-weld a portion of the joint, it is necessary that the old material be chipped out and new material added. After=Treatment. After the welding operation has been completed, the work should be heated very carefully and evenly until it is almost at a bright red heat. The weld should then be hammered while hot, so that the strength of the joint will be increased as much as possible. After the hammering has been finished, the work should be again reheated to a red heat and cooled quickly by means of an air blast or chilled by plunging in water. Care must be exercised in this operation if the work be a casting having confined, or rigid members, so that .cracking, or checking, does not occur. BRASS AND BRONZE WELDING General Considerations. Brass and bronze are both alloys of copper, brass consisting mainly of copper and zinc, and bronze of copper and tin. Both brass and bronze are welded in about the same general manner as copper, but because of the peculiar properties of the alloying metals, zinc and tin, it is necessary that they receive certain variations in welding. Oxidation. In both brass and bronze, the alloying metal is greatly affected by the high temperature of the flame, and the material OXY-ACETYLENE WELDING 75 will be subject to a loss of zinc or tin, unless proper precautions are taken. These metals will combine with the oxygen and pass off as white vapor, and leave a weld of different composition and color. Absorption of Gases. The molten metal in both brass and bronze absorbs certain gases very readily, and unless this absorption is counteracted, the weld will be spongy and weak. This may be taken care of by using a suitable welding rod and flux. Welding Rod. Because of the varying composition of brass and bronze, and because of the loss of the alloying elements when welding, it is practically impossible to produce welds of the same color as the original material. When welding brass, a good grade of drawn brass will be found most satisfactory, and in the case of bronze, a good drawn bronze, such as manganese or Tobin bronze. The cast rods that are on the market are not satisfactory, because it is quite impossible to cast a rod having the same composition throughout. Flux. The flux used for brass and bronze is practically the same as that used for copper. It should be applied by dipping the warm welding rod into the powder and adding it to the weld in this manner. It is not necessary to use as much flux as in welding pure copper, and care must be taken that an excess is not used, because the weld may become porous. Flame. A neutral flame must be maintained at all times for the same reasons as explained under copper welding. The blowpipe should be held between J to J inch from the metal. If the flame is held too close in the case of bronzes, the concentrated heat will cause a segregation or separation of the tin from the copper, and it will be practically impossible to again unite these elements. Preparation. The edges of the metal for a thickness of less than | inch may be merely butted together and welded, while for metals above this thickness the edges should be beveled or cham- fered, so as to allow penetration of the flame and insure a good weld. Welding. Because of the high conductivity of these materials, it is best that they be pre-heated to bring them to a suitable condition for rapid welding. Care must be taken when pre-heating bronze that it does not get too hot, because it is weak at high temperatures and is liable to break or crack under its own weight. The welding is carried on in about the same manner as for copper, and the blowpipe is handled in practically the same way. The welding 76 OXY-ACETYLENE WELDING rod should be in contact with the edges of the metal at all times, and the blowpipe should be played constantly on both the rod and the edges of the metal to keep them at the same temperature in order that adhesion may be prevented. Re-Welding. Re-welding should be avoided, but if it is absolutely necessary to re-weld the work, the section should be chipped out, and new material added, as in the case of copper. After=Treatment. Both brass and bronze should be annealed after welding by reheating evenly, and then allowed to cool slowly. Brass may be improved by hammering before the final annealing. Brass of low zinc content, i.e., red brass, should be hammered while hot, while brass of high zinc content, i.e., yellow brass, should be hammered cold. MISCELLANEOUS PROCESSES CUTTING Cutting In Automobile Repairs. The oxy-acetylene cutting blowpipe finds considerable application in the automobile repair shop for beveling the ends of shafts and other pieces of work preparatory Fig. 80. Beveling Round Shaft for Welding. The other piece is on the table Fig. 81. Beveling End of Heavy Square Shaft for Welding to welding, Figs. 80 and 81, cutting reinforcing plates out of large sheets for frame repairs, altering chassis, etc., Fig. 82. The cutting OXY-ACETYLENE WELDING 77 blowpipe is capable of doing this work cheaply and quickly, two necessary factors for the successful first-class repair shop. Principle of Cutting with Oxygen. At ordinary temperatures, steel oxidizes in the air, forming what is commonly called "rust". At a white heat it will oxidize more rapidly, as is seen in the black- smith shop when pieces are brought to a very high temperature. When steel is heated to a red heat, and a stream of pure oxygen is directed on it, the oxidation takes place more rap- idly and more violently and is restricted to the locality upon which the stream of oxygen is played. This localized oxi- dation is the basis upon which the oxy- acetylene cutting blowpipe operates. Metals That Can Be Cut. Steel and wrought iron are the only metals that can be cut successfully by means of the oxygen jet. Although cast iron, cop- per, brass, bronze, aluminum, etc., oxi- dize easily, nevertheless they cannot be cut. When the oxygen combines with the iron, heat is generated. This heat of formation, with the aid of the heat supplied by the pre-heating flames of the blowpipe, brings the oxide to a molten condition. The molten oxide either flows or is blown out of the cut and leaves a fresh thoroughly heated line through the metal for the further action of the cutting oxygen. In the case of steel and wrought iron, the oxide melts at a much lower temperature than the material being cut and therefore blows out without melting the surface of the material. In the cases of cast iron and certain alloy steels, the melting temperature of the oxide is as high and in some cases higher than that of the metal, and therefore melts the edges or freezes in the kurf and so hinders the cutting. Also, in the case of some of these materials, the heat of formation produced by the combination of the oxygen with the metal is not sufficient to carry the cut through the thickness of the work. Fig . 82 . Cutting Reinforcing Plate Out of Large Sheet Steel for Frame Repair 78 OXY-ACETYLENE WELDING Necessary Cutting Apparatus. A complete cutting station, Fig. 83, consists of the following apparatus: Cutting blowpipe with set of cutting nozzles Oxygen cutting regulator with two gages Acetylene regulator with one or two gages Adapter for acetylene cylinder One length high-pressure rubber hose for acetylene One length copper armoured hose for oxygen Darkened spectacles, wrenches, hose clamps, etc. Cutting Blowpipe. In the cutting blowpipe, Fig. 9, page 9, there are usually six small oxy-acetylene flames sur- rounding a center orifice through which pure oxy- gen is directed. The six heating jets are used only for the purpose of bringing the edge of the material to a tempera- ture at which the jet of pure oxygen will unite rapidly with the steel, as explained above. Cutting Nozzle. There are usually four sizes of cutting nozzles furnished for handling work of various thick- nesses, from very thin plate up to material 14 and 16 inches thick. Besides these, some manufacturers also fur- nish what is known as a "rivet cutting nozzle". This is a thin flat nozzle that can be laid against the sheet, allowing, the rivet head to be cut off close to the sheet. Fig. 83. Cutting Unit for Use with Acetylene in Cylinders, Mounted on Emergency Truck Courtesy of Oxweld- Acetylene Company, Chicago OXY-ACETYLENE WELDING 79 Working Pressure. The necessary pressures of the gas that are required by the different sizes of cutting nozzles and for the different thicknesses of material are given by the manufacturers. It is very important that the operator use these pressures instead of higher pressures because of the increased amount of oxygen used and the consequent high cost of operation, also because the cut will not be smooth if too much oxygen is used. Care of Blowpipe. If the blowpipe is handled properly there will be very little deterioration. It should only be necessary to clean the replaceable and working parts, repack the valves, and occasionally ream out and true up the nozzles. Care should be taken that the orifices of the nozzles do not become enlarged by reaming, because the heating jets will be made thicker and shorter and the cutting jet will spread rather than leave the blowpipe as a long thin stream. The blowpipe may be cleaned the same as the welding blow- pipe by removing both the acetylene and oxygen hose and connecting the nozzle to the oxygen hose, Fig. 16, page 18, and turning on the oxygen to a pressure of about 20 pounds per square inch, having first the cutting oxygen valve open, then the acetylene needle valve, and lastly the oxygen needle valve. This will allow the large particles to be blown out of the larger passages before they have a chance to clog up the smaller passages. Regulators. The cutting regulator, in principle, is the same as that described on page 20, but in size it is much larger than the welding regulator and is capable of both a higher delivery pressure and a greater volume. The acetylene regulator is the same as is used in the welding equipment, and described on page 20. Care of Apparatus. The blowpipe, regulators, and hose should receive the same care and attention as is explained for the welding apparatus on pages 18 to 21. Instructions for Connecting Apparatus. The regulators and the blowpipe are connected up in the same manner as the welding apparatus, and therefore the operator is referred to pages 22 to 23 for instructions. How To Light the Blowpipe. (1) Take the blowpipe in hand and open the oxygen cutting valve fully. 80 OXY-ACETYLENE WELDING (2) Turn the oxygen pressure-adjusting screw to the right until the required pressure for the work to be done shows on the low-pressure gage. (See the maker's chart for the correct pressure.) (3) Close the oxygen cutting valve. (4) Open the acetylene needle valve fully. (5) Turn the acetylene pressure-adjusting screw to the right until a good jet of acetylene issues from the heating orifices. In the case of pressure blowpipes, until the required pressure for the thickness to be cut shows on the low-pressure gage. (See the maker's chart for the correct pressure.) 6. Open the oxygen needle valve one-quarter turn and light the blowpipe by means of the pyro-lighter that is usually furnished. NOTE A back-fire might occur if there is not enough acetylene being supplied. If this occurs increase the acetylene supply by turning the acetylene pressure-adjusting screw farther to the right. 7. Adjust the acetylene pressure-adjusting screw to give a slight excess of acetylene to the -flame. 8. Adjust the acetylene needle valve to give a neutral flame (see under Flame Regulation, page 25) when the cutting oxygen valve is open. To Shut off the Blowpipe. In the case of the injector type of blowpipe, first close the acetylene needle valve and then the oxygen needle valve. In the case of pressure blowpipes, first close the oxygen needle valve and then the acetylene needle valve. To Cut. With the cutting valve closed apply the heating flames to the edge of the metal, keeping the nozzle at such a distance that the small flames barely touch the metal. As soon as the metal becomes heated to a cherry red, open the cutting valve, raise the blowpipe slightly to increase the distance between the nozzle and metal, and then move it along the surface as fast as a distinct and and clear kurf can be secured. The blowpipe should be held at a constant distance from the work. It should travel away from the operator in order that he may watch the cut advance. Back=Firing. Occasionally, particles of molten metal will impinge on the nozzle of the blowpipe, or the operator will allow the nozzle to touch the surface of the metal, and the blowpipe will back-fire. When this occurs, first close the acetylene needle valve OXY-ACETYLENE WELDING 81 and allow oxygen to clear the passage, then open the acetylene needle valve fully and relight. If the back-firing continues, close both the acetylene and oxygen needle valves, cool the blowpipe by plunging in water and relight. Other causes of back-firing are loose internal and external nozzles or dirt on the nozzle seat. These can be eliminated by tightening the nozzles and cleaning the seat. These back-fires are usually only a series of pops or sharp reports, and, as a rule, will not extinguish the flame. Notes on Cutting. Heating Flames. The heating flames should be small to produce smooth cutting. If the flames are too small, the blowpipe is liable to back-fire. If they are large, the top edges of the cut will melt and produce a rough cut. Speed of Cutting. The speed of the blowpipe travel should be slow enough to allow the oxygen jet to penetrate yet not so slow that the oxygen will be wasted. Restarting Cut. If the blowpipe travels too fast, and the cut is "lost", it is necessary to shut off the cutting oxygen and apply the heating flames to the point of stopping until the metal is hot enough to start the cut again. To Cut Round Shafts, Etc. The cutting of round pieces will be made easier if the surface of the work is first chipped with a chisel. This will present a good edge for the cutting blowpipe to bite on. To Pierce Holes. When piercing holes, a high oxygen pressure is necessary, and the metal must be brought to fusion before the cutting oxygen is employed. The blowpipe is held at a slight angle so the sparks will be blown out of the hole and away from the blowpipe. Cutting Dirty and Poor Material. If there is considerable rust, scale, paint, etc., on the surface, the cutting will be interfered with by small particles flying against the end of the nozzle and perhaps causing back-firing. To overcome this, the heating flames may be made longer, allowing the blowpipe to be held farther away from the surface, or the scale or paint may be removed by first passing the flame over the line of cutting before the cutting is started. LEAD BURNING Different Methods. Formerly, lead burning, or lead welding, was confined to garages and service stations that catered to the electric automobile only, but since the introduction of electric lighting and 82 OXY-ACETYLENE WELDING starting batteries for gasoline automobiles, lead burning has become one of the works of the repair man in all garages. It is therefore important that the repair man have a sufficient knowledge of this class of work to enable him to handle any work of this nature that may happen to come into his shop. Up to the time of the recent development of a very small oxy- acetylene blowpipe for lead-burning work, the hydrogen air burner was used by most lead burners. The oxy-acetylene blowpipe, how- Fig. 84. Oxy-Acetylene Lead Burning Apparatus Courtesy of Oxweld Acetylene Company, Chicago ever, is rapidly supplanting the old method and, as a matter of fact, within two years it has become universally accepted as being far superior to the old method in handiness of operation, speed, and consequent economy, and has been adopted by the large battery makers in both their factories and service stations. When an operator accustomed to the old flame tries the oxy- acetylene blowpipe, he is very likely to discredit it at first and claim that it is not satisfactory. However, every operator who gives the oxy-acetylene lead-burning blowpipe a fair trial and uses it in accordance with the methods recommended by the manufacturers OXY-ACETYLENE WELDING 83 of the apparatus must acknowledge it as being superior to any method he has ever used. Its advantages are emphasized even more emphatically if he returns to the old, slower, and more costly methods. Lead=Burning Apparatus. A complete lead-burning station for use with oxygen and acetylene, Fig. 84, consists of the following apparatus : Lead-burning blowpipe with set of tips Oxygen regulator with low-pressure gage Acetylene regulator with low-pressure gage Adapter for acetylene cylinder Valve-block Two lengths of high-pressure hose to connect regulators to valve block Two lengths of small hose to connect blowpipe to valve block Lead-Burning Blowpipe. To make the blowpipe as light in weight and as handy as possible there are no large valves. Instead, a valve block is furnished for regulating the gases, which may be attached to a bench or a wall. In order to make minor or finer adjustments of the flame, and to allow various size tips to be used on the blowpipe and still maintain a perfect flame, an adjustable injector is provided at the top of the blowpipe within reach of the operator's fingers. Tips. There are about five sizes of tips supplied for use on different thicknesses and various classes of work, each giving its own special size flame. The oxygen consumption of the various size tips ranges from | to 6 cubic feet per hour. For storage-battery work the average consumption is about 2 cubic feet per hour. Regulators. The regulators supplied with lead-burning apparatus operate on the same principle as the regulator described on page 19, the only difference being that they are of smaller size and especially adapted to small flames. Operation of Lead=Burning Apparatus. The apparatus is connected in the same general manner as the welding apparatus for which instructions are given on pages 22 to 26. The needle valves on the valve block are used to obtain approximate adjust- ment of the flame, and then the small thumb-nut on the blowpipe is used to make the finer adjustment. The pressure-adjusting screws should be set to give pressures of about 10 pounds per square inch for the oxygen, and 2 pounds per square inch for the acetylene. 84 OXY-ACETYLENE WELDING The blowpipe, regulators, hose, etc., should receive the same care and attention as the welding apparatus and for which suggestions are given on pages 18 to 21. Lead=Burning Process. The oxy-acetylene blowpipe should be handled in such a manner that the flame strikes the work perpen- dicularly. If the blowpipe is used on a slant, the inner cone will not bring the work to the fusing temperature as rapidly as if held vertically, and the secondary flame, or outer envelope, will be very likely to heat the surrounding metal to such a temperature that it will give way and break under its own weight. When working with the oxy-acetylene flame on stor- age batteries and the like, the operator should do the burning quickly. He should bring the flame down to the work, fuse the metal, add the necessary burn- ing bar, or filling wire, smooth off the work, and remove the flame, all as rapidly as possible. Burning Terminal Groups. When burning plates to terminal bars, a small flame should be used, and the work should be held in a fixture, as shown in Fig. 85. The small ends on the plates should extend up into the terminal bar slots about two- thirds of the way. The burning should be carried on by first fusing the ends of the plates to the bottom of the slots, then filling up the rest of the slot by adding lead from a coil of wire or a burning bar. After the several plates have been burned on in this way, the flame should be moved perpendicularly over the surface to smooth it off and leave a nice finish. The flame should not be held flat against the work. It will take longer to smooth off the work, and it will not have nearly as neat an appearance if the flame is used flat. Burning-On Connecting Links. The terminal poles should extend up into the links about one-third of the way. The flame should be brought down into the hole until the inner cone almost Fig. 85. Assembling Terminal Groups OXY-ACETYLENE WELDING 85 touches the top of the pole, and the pole fused and united with the bottom of the link as quickly as possible. After a good union has been secured in this manner, the burning bar should be introduced and the rest of the cavity filled up, Fig. 86. When working on links and poles it is advisable to do only part of one pole, move to another for a few minutes, and then come back to the first for a few minutes. This will allow the work to cool off slightly and will prevent breaking down or melting away. When burning this class of work, especially if the lead is old and pitted with dirt and cut by acid, it is advisable to increase the supply of oxygen and use an oxidizing flame when working down in the pocket. This will burn out any dirt and will prevent the blow- pipe from puffing out when it is burning in the rare atmosphere that exists in the pocket. Forms or Molds. Small steel frames, or molds, are found very convenient, e s p e ci a 1 1 y when working on terminal links. These molds are shaped to con- form to the work and are placed around it while burning. They are a great help in preventing the corners of the work from break- ing down and melting away and, in this manner, relieve some of the tediousness of the work and allow the operator to work under less strain, and permit the work to be done by men who are not skilled lead burners, but who have occasional work of this sort to do. Fig. 86. Burning-On Connecting T.inlp* CARBON REMOVING BY USE OF OXYGEN Methods. Old Process. Up to within the last few years the methods used for removing the carbon from gas-engine cyl- inders were very impractical and unsatisfactory. To do this work meant the dismantling of the motor, the removal of all the parts, and the scraping of the cylinder walls by hand. Because this 86 OXY-ACETYLENE WELDING operation necessitated a great deal of work it was not done, in most cases, until the carbon deposit became very heavy. Oxygen Process. The introduction of the inexpensive process of removing the carbon by burning it out by means of pure oxygen has replaced the old methods and they are no longer used. This new process is so simple, necessitates so little work, can be done so quickly and cheaply, that it can be employed every few months and, in that way, keep the cylinders free from carbon. Carbon=Removing Apparatus. Complete apparatus for remov- ing carbon by means of oxygen, Fig. 87, consists of the following: Carbon-removing handle with flexible tube Oxygen regulator with low-pressure gage One length of high-pressure rubber hose It will be seen from this list that all that is necessary for a garage to have in addition to its welding equipment is the carbon- removing handle with a flexible tube. Burning Out Carbon. Shut off the gas- oline at the tank or just in front of the carburetor and allow the engine to run until it has sucked the gasoline out of the lines. Remove the valve caps and spark plugs from all the cylinders. Turn the engine over by hand until the first piston is at the upper end of its stroke and both its valves are closed. Intro- duce a/ small quantity of kerosene into the cylinder head by means of an oil can or a piece of saturated waste. Light the kero- sene in the cylinder, introduce the end of the flexible tube into the cylinder and allow the oxygen to play on the carbon at a pressure of about 5 pounds per square inch. The carbon deposit will catch fire and will continue to burn as long as there is carbon present. Of course, if the carbon is depos- ited in patches it will be necessary, after one patch has been removed, to start another by means of kerosene. After the first cylinder has been thoroughly cleaned, turn the engine over by hand until the piston of the second cylinder is at Fig. 87. Carbon-Removing Apparatus OXY-ACETYLENE WELDING 87 its upper stroke with its valves closed, and then proceed to remove the carbon from this cylinder in the same manner. After all the cylinders have been thoroughly cleaned, clean the valve caps and spark plugs by scraping or by burning off the carbon and then replace them in the engine. Notes on Carbon Burning. Before burning out the carbon be sure that there is no chance of gasoline being present which might cause back-firing into the intake manifold. The oxygen pressure should not be too high. Only enough oxygen should be supplied to keep the carbon kindled. Too much pressure will waste oxygen and increase the cost of burning out the carbon. Too much kerosene must not be used, because there is a chance of the operator burning his hands with the sudden burst of flame that might result. EXAMPLES OF AUTOMOBILE REPAIR Pressed=Steel Parts. All pressed-steel parts of automobiles, such as frames, bodies, fenders, axle housings, tubing, etc., should be welded, using a pure iron welding wire for a filling material. Frames. Almost all frame repairs necessitate a certain amount of dismantling of other parts. The extent of the dismantling depends upon the location of the proposed weld. If the work is to be done under the body, it is best to remove the car body. This is not absolutely necessary, however, because the work can be done by merely jacking up the body several inches to give enough room to do the work, and protect the body from the heat of the welding flame. If the weld is to be done close to the radiator, this should be removed so that the solder will not be melted out, Fig. 88. If the weld is about 12 inches from the radiator, the solder can be protected by placing sheet asbestos over the radiator. In this connection it is well to remind the operator that it is always advisable to cover the parts of the car near the welding with sheet asbestos to protect them from any possibility of the flame or heat getting too close. Jacks should be placed under the frame and the frame brought into alignment before the welding is started; the jacks should not be removed until the weld has been completed and has become thoroughly cooled. 88 OXY-ACETYLENE WELDING It is always advisable to bevel the work by chipping. In the case of frames of light-weight pleasure cars this may be dispensed with if the operator is careful to penetrate through the thickness of the material. All paint, dirt, and grease must be scraped off next to the weld from both the inside and outside of the frame before the welding is commenced, to prevent dirt from being incorporated in the weld. A reinforcing plate should be prepared about the same thickness as the frame, as wide as the frame is high, and about three times Fig. 88. Radiator Is Removed if Welding Flame Is Near It as long as it is wide. This may be cut out of sheet steel by means of the cutting blowpipe, Fig. 82, page 77, or by means of a hack saw. The blowpipe is the quickest and easiest method, especially for cutting plates for curved frames such as are used on pleasure cars. The weld will look better if the reinforcing plate is welded on the inside of the frame, but in some cases that is impossible without a great deal of extra dismantling. It is then allowable to weld it on the outside. The welding should start at the lower end of the frame and move upward as explained under Vertical Welding, page 31. The OXY-ACETYLENE WELDING 89 two flanges of the channel should then be welded, starting at the corner and moving toward the edge. When welding the lower I Fig. 89. Badly Bent Frame Fig. 90. Frame after Heating with Welding Flame and Straightening 90 OXY-ACETYLENE WELDING flange, the work should be carried on as explained under Overhead Welding, page 31. After the frame has been welded, the reinforcing plate should be welded on by welding the horizontal edges first and the ends last. The weld will be materially strengthened if it is hammered during the process of welding, as explained under Hammering, page 46. The oxy-acetylene blowpipe is also very valuable in straightening frames that have become bent in accidents. A frame of this sort is shown before and after straight- ening in Figs. 89 and 90. Bodies and Fenders. Bodies and fenders that have been torn can be successfully welded if the operator uses his best efforts and is careful. Fenders, as a rule, do not present very much difficulty be- cause the break usually extends to the edge. It is advisable to pack wet asbestos along both sides of the weld to prevent buck- ling as much as possible, Fig. 91. The wet asbestos will absorb the heat and will not allow it to be conducted back into the sheet. Bodies should be welded in a similar manner when they are torn. If possible, it is advisable to bend the edges outward slightly before welding. Then, as the weld is cooling, hammer it flat to compensate for the contraction that takes place. If a patch must be welded in, it should be prepared either round or oval, or should have rounded corners of large radii. The patch should be dished to compensate for the contraction that will take place when the work cools. The hole in the body and the patch should be trimmed so as to fit well. When the patch is ready, it should be tacked in place. The welding should be carried on as quickly as possible. After the weld has Fig. 91. Welding along Weld Will Prevent Buckling Torn Fender. Wet Asbestos Will Prevent . of Light Sheets OXY-ACETYLENE WELDING 91 been completed, the flame should be played on it to heat it evenly. As the weld starts to cool, the center of the patch should be heated Fig. 92. Broken Front Axle Fig. 93. Welded Front Axle Fig. 94. Crankshaft in Crankshaft Jig Table for Welding slightly so that it will stretch easily and compensate for the con- traction taking place in the weld. 92 OXY-ACETYLENE WELDING Springs. The welding of springs should not be attempted except for emergency repairs to allow the car to be used until a new spring can be obtained. A steel welding rod of low-carbon content 4 Fig. 95. Pre-Heating Crankshaft with Gas Burner Fig. 96. Welding Crankshaft. Note that the Pre-Heating Burner Is Used to Assist the Welding Flame should be used for filling material. No attempt should be made to re-temper the spring, because the average garage is not equipped to handle work of that nature and, consequently, the spring is very Fig. 97. Welded Crankshaft likely to be worse if a poor job of tempering is done than if tempering is not attempted. It is well to pack wet asbestos around the spring next to the weld to prevent the heat being conducted back into the rest of the spring. OXY-ACETYLENE WELDING 93 Shafts and Axles. Shafts and axles are alloys of nickel, nickel and chromium, or chromium and vanadium. It is desirable to have the filling material of the same composition as the shaft or axle, but this is practically impossible. The most suitable welding rod Fig. 98. Broken Malleable-Iron Rear-Axle Housing that can be obtained for this work is one containing about 3.50 per cent nickel, or one containing about 0.20 per cent vanadium and 0.12 per cent chromium. This latter steel is more difficult to handle under the welding flame, so that most welders prefer the 3.50 per cent nickel rod. Square shafts, Figs. 92 and 93, and round shafts, Fig. 80, page 76, should both be beveled by means of the cutting blowpipe or by grinding, and should then be placed in alignment or in suitable jigs, Fig. 94. A gas or oil pre-heating burner should then be directed Fig. 99. Repaired Malleable-Iron Rear-Axle Housing on the point of welding, Fig. 95, and the work heated to a red heat before welding is started. The welding should then be carried on, Fig. 96, according to the instructions given under Welding Heavy Sections, page 58. After the welding has been completed the work should be reheated and any straightening done that is necessary. 94 OXY-ACETYLENE WELDING The weld should then be heated up evenly, covered over with sheet asbestos, and allowed to cool slowly. The finished weld is shown in Fig. 97. Axle Housings. If the housing is of pressed steel, it will not present any particular difficulty to the welder, except that he will have to take care that it does not get out of alignment. A pure iron welding wire should be used, and the work should be prepared and carried on as explained under Light Sheet-Steel Welding, pages 46 to 50 If the housing is of malleable iron, Figs. 98 and 99, it should be beveled, placed in alignment, and then brazed, using Tobin bronze for a filling material as explained under Malle- able-Iron Welding, page 67. The work may be pre-heated slightly to re- lieve the effect of expan- sion and contraction, but must not be heated above a dark red. The operator must be very careful to not bring the malleable iron at the weld to too high a heat or its mal- leable properties will be destroyed and the hous- ing will be weak. Manifolds. Pressed- steel manifolds should be Fig. 100. Welding Broken Flange on Manifold we lded according to the directions given under Light Sheet-Steel Welding, pages 46 to 50. Cast-iron manifolds, as a rule, have only simple breaks to be repaired, such as broken flanges, Fig. 100. These should be beveled, and the parts clamped to a flat surface to keep them straight. They should then be pre-heated in the vicinity of the weld by means of the welding blowpipe before the welding is started. After the weld is completed they should be reheated evenly and then covered over and allowed to cool slowly. OXY-ACETYLENE WELDING 95 Engine Cylinders. If the water jacket is cracked, the crack should be chipped out and the surface of the casting next to the groove should be cleaned by scraping. If the cylinder is cracked in Fig. 101. Water Jacket Cut Away to Allow for Welding Cylinder Wall the head end, it will be necessary to cut away a section of the water jacket by drilling or sawing, Fig. 101. After the cylinder head has been welded, the water-jacket section can be welded back into place, Fig. 102. Sometimes it is quite difficult to detect how far the crack really extends, therefore, care must be taken to be sure that it is chipped out its entire length. All of the plugs and other fittings must be removed from the cylinders before pre-heating. The cylinders should be placed in Fig. 102. Cylinder Wall Welded and Section of Water-Jacket Replaced the pre-heating fire with the open end of the cylinder upward, Fig. 103. They may be placed on a slant if the crack is on the side of the water jacket; but they must be in such a position so there 96 OXY-ACETYLENE WELDING will be no chance for dead air to remain in them. If this precaution is not taken, the cylinder walls are very likely to crack. The welding should be carried on according to the directions given under Cast-iron Welding, pages 59 to 67. The cylinders must be left in the charcoal fire all during the welding. It is even advisable to keep the top of the fire covered over and to weld through a hole in the asbestos paper, Fig. 103, to prevent air currents from striking the cylinder while it is hot. After the welding has been Fig. 103. Welding Cylinders and Preparing Pre-Heating Fire for Cylinders completed, the fire should be started up enough to heat the entire casting evenly, and should then be covered over and allowed to die out. The cylinder must not be removed until it has become cold enough to be handled with bare hands. Protection for Machined Surfaces. The finish in the bore of the cylinder will be affected by the heating if some means is not used to protect it. The best protection that can be used is to coat it and other machined surfaces with flaked graphite and oil. This can be made into a paste and painted on, or the surfaces can be oiled OXY-ACETYLENE WELDING 97 Fig. 104. Water Jacket Plugged and Welds Being Tested Gasoline with and the graphite dusted on. The latter method is really the best if carefully applied. The graphite must be coarse; the fine flake will not do. Testing Welded Cyl- inders. There are sev- eral ways of testing welded cylinders. The two most generally used are by water pressure and by gasoline. In the first method, the water jacket is tightly plugged, filled with water, and then subjected to pres- sure by means of a hand pump. The method of using gasoline is simpler and quicker. The water jacket is plugged and filled with gasoline, Fig. 104. If there are any cracks or leaks the gas- oline will work its way through and will spread out over the surface sur- rounding the crack or leak. Crankcases and Transmission Cases. It is usually necessary to remove the case from the car. But, if the arm is broken some distance from the main case, it may be welded while in position, as shown in Fig. 105. When welding in this manner, it is necessary to cover the parts near the welding with asbestos sheets to protect them from the flame of the blowpipe. The arm should be Fig. 105. Welding Arm of Crankcase without Dismantling OXY-ACETYLENE WELDING pre-heated slightly by means of the welding blowpipe before the actual welding is started, and, after the welding has been completed, it should be reheated to relieve any internal strains, and must then be covered over to allow it to cool slowly. Some operators spend a great deal of time trying to keep the bearing of the case in line, and while doing this they allow the rest of the case to twist, so that it is necessary to take a machine cut off the edges in order that they may fit the other half of the case. It is much better to keep the edges true and dress up the bearings, because it is quite likely that the bearings will have to be trued up anyway. The case should be clamped flat against two straightedges, but not too tight, or the case might crack from the strains produced when heat is applied. The case should be placed on the welding table in such v a position that the welder can work on the outside and smooth off the inside without having to disturb its position. The most satisfactory method of pre-heating is to place Fig. 106. Badly Broken Transmission Case Must Be Pre-Heated All Over Fig. 107. Lower Half of Crankcase with Piece Broken Out Must Be Entirely Pre-Heated Fig. 108. Upper Half of Crankcase with Piece Broken Out and Missing a gas burner under the case and let it burn without an air blast. If an air blast is turned on, the case is liable to become overheated and OXY-ACETYLENE WELDING 99 cave in. In fact, unless there are holes to allow some of the heat to escape, the case is liable to become overheated with only the soft gas flame. If the case is broken at one end, as shown in Fig. 108, it is only necessary to heat the one end; but it is very necessary to heat both sides of that end to prevent warping. If like the case shown in Figs. 106 or 107, it is best to heat the entire case. This can best be done by using two gas burners so that the heat will surely spread. If the case is cracked or a piece is broken off, the welding should start at the inner end of the crack and move toward the edge or corner. The welding should be carried on as directed under Cast Aluminum Welding, page 71. If a piece has been broken out and lost necessitating building Fig. 109. Sheet-Iron Form to Back Up Section to Be Welded-In up a section of the casting, Fig. 108, it is necessary to back-up the work by means of a piece of sheet iron bent to the required shape, Fig. 109. The welding should be started at one edge and should move across the space in a line parallel to the edge. When the added material gets almost to the opposite edge, the welding should stop, the edge of the case and the edge of the new added section should be cleaned, and then the weld completed in the same manner as for welding up a crack, Fig. 110, as outlined above. COSTS The cost of welding varies within wide limits for the different metals and the different classes of work. It is, therefore, not possible to give cost tables that will apply to all work. The costs given in Tables II and III are for steel work under fair conditions. Measuring Oxygen Consumption. Oxygen is supplied compressed to 1800 pounds per square inch, in cylinders containing 100 OXY-ACETYLENE WELDING TABLE II Welding Cost Table Thickness of Metal (in.) Speed (ft. per hr.) Oxygen per Linear Foot (cu. ft.) Acetylene per Linear Foot (cu. ft.) Cost per Linear Foot Labor 45c Oxygen. . . . 2c Acetylene. . 2Jc <& 26 0.15 0.14 $ .024 A 22 0.22 0.21 .030 & 17 0.43 0.41 .045 h 14 0.68 0.65 .063 i Hi 1.03 0.98 .083 A 9 1.84 1.74 .13 1 7 3.01 2.88 .20 f 4| 6.74 6.44 .40 i 3 13.2 12.5 .73 I H 38.7 37.0 2.00 i l 76.7 72.9 3.81 TABLE III Cutting Cost Table Cost Thickness of Metal (in.) Speed (ft. per hr.) Oxygen per Linear Foot (cu. ft.) Acetylene per Linear Foot (cu. ft.) per Linear Foot Labor 45c Oxygen .... 2c Acetylene.. 2jc i 90 0.34 0.10 $ .014 i 74 0.55 0.17 .021 * 55 1.16 0.33 .040 a. 4 46 1.91 0.47 .060 1 40 2.75 0.61 .082 i* 33 4.70 0.85 .13 2 29 6.97 1.06 .18 3 24 12.3 1.46 .30 4 20 19.4 1.96 .46 6 15 38.3 3.04 .87 8 11 69.7 4.60 1.55 TABLE IV Factors for Correcting Oxygen Volumes Deg. F. Factor Deg. F. Factor Deg. F. Factor 100 0.929 75 0.972 50 1.020 95 0.937 70 0.981 45 1.030 90 0.946 65 0.990 40 1.040 85 0.954 60 1.000 35 1.051 80' 0.963 55 1.010 30 1.061 101 OX Y- ACETYLENE WKLD-JNti 100 and 200 cubic feet. The amount pf oxygen im a; tyHafe^ be measured quite accurately by means of the high-pressure gage on the regulator. Most of these gages are supplied with two rows Fig. 110. Upper Half of Crankcase with Section Built-in of figures on the dial, Fig. 111. The outer circle gives the pressure in the cylinder in pounds per square inch, and the other circle gives the per cent of oxygen remaining in the cylinder. The latter set of numbers makes the calculation very easy: e.g., if a 100-cubic foot cylinder is being used and the gage hand indicates 73, there is 73 ACETYLENE CO. UVU50-NEWYORK Fig. 111. Dial of High-Pressure Gage of Oxygen Regulator cubic feet of oxygen in the cylinder. If a 200-cubic foot cylinder is being used, there is 200X0.73 = 146 cubic feet in the cylinder. The amount of oxygen indicated by the gage reading is more or less approximate and depends upon the temperature of the oxygen in the 102 OXY-ACETYLENE WELDING cylinder. The correction factors given in Table IV should be used to determine the volume of the oxygen at "standard temperature", 60 F., if an accurate measurement is required, e.g., if in the case given above the temperature is 50 F., then the real volume at standard temperature would be 146X1.020 = 148.9 cubic feet. Measuring Acetylene Consumption. The amount of acetylene in a cylinder cannot be determined by means of the high-pressure gage. All the high-pressure gage can be used 'for, in the case of acetylene, is to indicate very roughly the amount of acetylene in the cylinder. There is only one method that can be used to determine the amount of acetylene used, and that is to weigh the cylinder. Each pound by weight of acetylene is equal to 14.5 cubic feet. There- fore, to determine the amount of acetylene used on a certain job, it is necessary to weigh the cylinder before and after welding and calculate the volume of acetylene used from the difference in weight, e.g., if the cylinder weighs 217 pounds before welding and 207 J pounds after welding, then (217 -207|)X 1.4.5 = 9JX 14.5 = 137.7 cubic feet. INDEX INDEX PAGE Acetylene 4 consumption 102 cylinders 4 generators 5 Adhesion 33 After-treatment 45, 66, 70, 72, 74, 76 Aluminum welding 68 cast 71 sheet 69 Annealing 45 Automobile repair, examples 87 axle housings 94 bodies and fenders 89 crankcases and transmission cases 97 engine cylinders 95 frames 87 manifolds 94 pressed-steel parts 87 shafts and axles 93 springs 92 B Back-firing 24 Blowholes 66 Blowpipe : 7, 16 how to light 23 how to shut off 23 inclination 27 injector 7 manipulation 28, 44, 63 position 27 pressure 7 Brass welding 74 Bronze welding 74 Butt weld . 49, 54 C Carbon removing by use of oxygen 85 Carbon blocks 67 Cast-iron welding 59 Charcoal fire 43 Connecting apparatus, instructions f or , , 22 INDEX PAGE Copper welding 72 Corner welds 50, 54 Costs 99 Cutting 10, 76 apparatus 78 principle 77 Cylinder welding 49, 54 D Defects in welds 32 E Electric welding 11 apparatus 13 arc welder 12 spot-welder 11 Expansion and contraction 8, 36, 43, 46, 53, 58, 60, 68 complex case 39 methods of handling 37 simple case 37 F Flange weld 49 Flux 9, 61, 69, 73, 75 G Generators 5 low-pressure 5 pressure 6 Graphite electrode 13 H Hammering 9, 46, 59 Holes, welding up 31 Hose.. . 21 Jigs 47 Lead burning 81 apparatus 83 M Malleable-iron welding 67 Metallic electrode 13 Metals, properties of 34 INDEX O PAGE Overhead welding ..................................................... 31 Oxidation ............................................. 32, 43, 59, 68, 72, 74 Oxy-acetylene flame ..................................... 8, 24, 44, 69, 73, 75 Oxy-acetylene process ....................... ' .......................... 3 advantages ...................................................... 3 Oxygen .............................................................. 3 consumption ..................................................... 99 P Penetration ......................... .................................. 33 Pipe welding ......................................................... 56 Pre-heating ..................................................... 40, 60, 71 methods ......................................................... 41 reasons .......................................................... 40 Preparation of work for welding ................ 8, 14, 46, 51, 57, 62, 71, 73, 75 Regulators ........................................................... 19 acetylene ........................................................ 20 care ............................................................. 21 cutting ..... -. ................................ .................... 79 operation ............................. ........................... 19 oxygen welding ................................................... 20 Reinforcing welds ............................ ......................... 34 Re-welding ..................................................... 70, 74, 76 Rods .......... . ................................... 8, 29, 44, 60, 68, 72, 75 S Spot-welder .......................................................... 11 Steel welding ....................... . ................................. 43 castings. .... .................................................... 57 f orgings ......................................................... 57 heavy sheet ...................................................... 51 light sheet ....................................................... 46 Strength of welds ..................................................... 9 T Tables cutting cost table ............ ..................................... 100 factors for correcting oxygen volumes ................................ 100 properties of metals ............................................... 35 welding cost table ........................ ......................... 100 Tacking ............................................................. 47 Tank welding ................................................... 51, 55; 56 Tube welding ...................................................... 51, 56 V Vertical welding ...................................................... 31 INDEX W PAGE Welding 15 brass 75 bronze 75 cast aluminum 71 cast-iron 63 copper 73 heavy sheet-steel 53 light sheet-steel , 48 malleable-iron 68 sheet-aluminum 70 steel castings 58 steel f orgings 58 Welding processes 1, 63 electric 11 old and new methods 1 oxy-acetylene 3 LD21-100m-7,'33 YC 13848 UNIVERSITY OF CALIFORNIA LIBRARY