CHAPTER VISteam Hammer, Tools, and Exercises

Fig. 99.—Steps in Making Calipers.

Other conditions arise, however, to modify these rules. If the heat is unevenly distributed, or if the stock is not of a uniform thickness, the results will not be exactly asestimated. When a heavy ring is formed of oblong material and bent through its larger diameter, as shown in sketchA,Fig. 100, and the product is to be finished to a uniform thickness, the expansion of the outer portion will make it necessary to use somewhat thicker material, to provide for the decrease of metal which will take place. The inner half, then too thick, could be reduced to the required size, but this operation always alters natural conditions of bending, and changes the general results. These conditions are not very noticeable and do not require special attention when small-sized materials are operated upon, but they must be observed when large oblong or square stock is formed into a ring requiring exact dimensions.

Fig. 100.—Calculations of Lengths for Rings.

In all cases of this kind, the required length must be established from the undisturbed center and the ends cut at an angle of 85 degrees. If the material is to be welded, it should be scarfed on opposite sides and lapped when bent.

When hoops or bands of flat or oblong material arebent, scarfed, and welded through the small diameter, then both scarfs should be formed on the same side while straight, and bent as shown atB,Fig. 100; the scarfs then will fit more readily than if they were formed on opposite sides. Sometimes, in instances of this kind, only one end is scarfed, and the piece is bent in a similar manner, with the unscarfed end on the outside and just lapping enough to cover the heel of the inner scarf.

Another form of ring requiring a calculation of the area as well as of the length is one of a wedge-shaped section, as shown atC,Fig. 100. Here the area of the required section is found and the material supplied with the proper thickness and area. The length also must be computed, then cut, scarfed, and welded, as previously explained; after this the ring may be drawn to the form desired.

The circumference of a circle may be found by multiplying its diameter by 3.1416 (π). (See tables, pages205-206.) For rings or bands the length of the center line,c,Fig. 100, should be found. Example: Ifaequals 5 inches andbequals 2 inches,cwill equal 7 inches, and the length of stock for the ring will be 7 × 3.1416 = 21.991 inches,—practically 22 inches. 31⁄7may be used for the value of π instead of 3.1416.

Questions for Review

Describe the proper construction of a pair of tongs. What sort of steel should be used in making lathe tools? What operations are employed in making them? What is the color of the temper? If they were tempered to a blue, would they be tempered harder or softer? Are forging and hardening heats the same? State the difference in grinding a boring and a threading tool. Explain the differencein making a right- and a left-hand diamond point tool. How should a side tool be hardened? Why shouldn’t the head of a cold chisel be cooled off quickly when it is finished? Explain the difference between tempering a cold chisel and tempering a lathe tool. Describe the shapes of the hot and the cold cutter. How should they be tempered? How are the square-edged set and the flatter treated in place of tempering. Explain how it is done. Describe different methods of making eye or ring bolts. How should measurements be made on stock to be bent? State what has been said about scarfing flat or oblong material for rings.

112. A Forging.—A forging is an article made of metal, generally steel or iron, and produced by heating and hammering. It may be used for either practical or ornamental purposes. The various forgings already described were made by methods such as the older class of smiths practiced, and are called hand forgings. From a practical standpoint these smiths were familiar with the characteristic composition of metals and with the knowledge of how they should be worked.

Many forgings are produced at present by machinery. The product is satisfactory for most practical purposes, and is generally equal to that made by hand. The machines used are the drop hammers, horizontal and vertical presses, steam hammers, and numerous other devices. The power used for operating them may be either steam, air, water, or electricity.

113. The Drop Hammer.—The drop hammer is provided with a pair of dies made of cast steel, one upper and one lower, having suitably shaped depressions made in them for forming the forgings. The lower die is held stationary on a solid foundation block, and the upper one is secured to a heavy weight or hammer. This is raised perpendicularly and allowed to drop upon the metal, which is held on the fixed die by the smith, thus forming the forging.

If the work is small and simple, all depressions may be made in a single pair of dies, and the forging can be completed with one hammer and without changing the dies. Work somewhat complicated may require two or more pairs of dies, with various shapes of depressions. The stock is broken down or blocked out by the first pair and then completed by the stamping and finishing dies. Larger pieces may require also a number of pairs of dies, then an equal number of hammers may be used, each fitted with a set of dies. The material is passed from one to the other, and the work completed without changing dies, and possibly without reheating the metal.

114. Presses.—Presses may be either horizontal or vertical and are generally used for bending or pressing the metal into some desired shape or form; they are quite convenient for producing duplicate and accurate shapes. Forming-dies or blocks are also required here, but they are generally made of cast iron, and their construction need not be so accurate. After the presses have been properly adjusted, very little skill is required in their operation,—simply the heating of the material and placing it against a gauge or between the dies. One thrust of the plunger will complete the operation.

115. The Steam Hammer.—The steam hammer was first recorded by Mr. James Nasmyth in his “scheme book” on the 24th of November, 1839. Although this was the exact date of its origin, he first saw it put into practical use by the Creuzot Iron Works of France in 1842. Nasmyth’s invention legally dates from June, 1842, when his patent was procured.

Of the various machines that have been devised for thesmith’s use, to relieve him of the laboriousness of pounding metal into shape, there is none that could take the place of this invention. Numerous shapes and forms can be produced more accurately and rapidly by the employment of the steam hammer than by the use of hand methods.

Fig. 101.—A Steam Hammer Equipped with a Foot Lever.

Before proceeding any further, a few words of warning and advice may not be out of place. Although this invention is a great benefactor to the smith, it is not possessed with human intelligence, nor is it a respecter of persons. The power of steam will always exert its utmost force when liberated, so do not let in too much steam at first. Unless the material is held horizontally and flat on the die, the blow will jar the hands badly and will bend the material. All tools such as cutters and fullers should be held firmly but lightly, so that they may adjust themselves to the die and the descending blow.

After the hammer has been put into motion, the blowswill fall in a perfectly routine manner. By his careful observation and a thorough understanding of the necessary requirements, and by signals from the smith, the hammer operator should regulate the force of the blows to suit the smith’s convenience.

A caution pertaining to the tongs used for handling the material should be carefully observed. Whenever work is to be forged with the steam hammer, the material should be held with perfect-fitting tongs secured by slipping a link over the handles; a few light blows delivered on the link will tighten their grip.

116. Steam Hammer Tools.—First some necessary tools will be explained, then exercises requiring their use will be given, followed by a few operations where simple appliances are needed.

Fig. 102.—The Hack or Cutter.

117. The hack or cutter(Fig. 102) is used for nearly the same purposes as the hot cutter already described. It should be made of tool steel from 0.80 to 0.90 per cent carbon. The head or top is made convex, as shown, and not more than5⁄8inch thick, tapering equally on both sides to the cutting edge, which may be made either3⁄16or1⁄4inch thick. It should be ground straight and parallel to the top and tempered to a dark blue.

The blade is about 21⁄4or 21⁄2inches wide, unless intended for heavy forgings, when all dimensions should be increased.The width of the blade should not be too great, however, for the broader the cutter, the greater its liability to glance sidewise or turn over when the blows are delivered upon it. The length of this cutter may be from 33⁄4to 4 inches.

The handle may be about 28 inches long, approximately3⁄4inch in diameter ataand gradually tapered towards the end, where it is about1⁄2inch. The portion indicated atbis flattened to an oblong section, as shown, to allow springing when the blows are delivered and to prevent bruising the hands.

118. The circular cutter(Fig. 103) is made of the same material and with a handle of similar dimensions and form as the hack. A section of the cutting portion ona-ais shown, and suitable dimensions given. If convex ends are to be cut, the perpendicular side of the blade should always be on the inner side of the curve, but on the outer side for concave ends.

Fig. 103.—The Circular Cutter.

An assortment of these cutters with various-sized arcs may be provided to suit requirements, but quite frequently the curved cutting portion is altered to suit the particular work at hand.

Fig. 104.—The Trimming Chisel.

119. The trimming chisel(Fig. 104) is made quite similar to an ordinary hot cutter and likewise provided witha wooden handle. It should be strongly constructed, perfectly straight on one side, and not too long from the cutting edge to the top to avoid its being turned over when the blows are delivered upon it. The grinding should be done on the tapered side only, with the cutting edge tempered to a dark blue.

120. The cold cutter(Fig. 105) is used for purposes similar to those of the ordinary cold cutter. It should be strongly made in a triangular form, as shown in the end view, also with a spring handle like that of the hack. The top is made convex, and the sides taper to the cutting edge, which should be ground equally from both sides. It should be carefully tempered for cutting cold material.

Fig. 105.—The Cold Cutter.

Fig. 106.—Breaking Cold Stock.

In cutting stock with this tool, the material should be nicked sufficiently deep on the exterior to allow it to be broken. By holding the piece securely with the hammer, and the nicked portion even with the edge of the dies, it may be broken off by a few blows from a sledge. The steam hammer may also be used to break the stock when nicked with the cold cutter. The piece should be placed on the lower die of the hammer, as shown inFig. 106, and broken by one or two sharp blows from the hammer. A piece of round stock can be used instead of the triangular piece of steel, with the same result. When material is being broken in this way, see that noone is standing in a direct line with the stock, as there is some liability of one or both pieces flying in either direction.

Fig. 107.—Cutting Stock.

When using the hack (Fig. 102) for cutting square stock, cut equally from all sides, as shown ata,Fig. 107. This will produce smoother ends than if it were cut unequally and will prevent the short end from turning upward when the final blows are delivered. The fin or core that is formed by the hack, shown atb, generally adheres to one of the pieces, but it can be removed by using the trimming chisel in the manner shown. These fins are commonly removed by the use of an ordinary hot cutter and sledge.

The hack, if held perpendicularly, will not cut the end of either piece square. If one end is to be cut square, the cutter should be held as shown atc. Round material may be cut similarly, but to avoid marring its circular section it may be held in a swage fitted to the hammer die.

Flat stock may be cut equally from both sides, or if it is cut nearly through from one side, the operation can be completed by placing a small piece of square untempered steel over the cut, as shown ate. A sharp blow of thehammer will drive the steel through into the opening and produce a straight, smooth cut.

When a semicircular end is to be produced, similar to that indicated by the broken line atd, the circular cutter should be used. Here, also, the cutting should be done equally from each side.

Fig. 108.—The Checking Tool or Side Fuller.

121. The checking tool or side fuller(Fig. 108) is made of tool steel with a carbon content, the same as for the cutters. The handle also is the same, with the exception of parta, which provides the spring. Here, on account of its being used in two different positions, a twisted form is much better, because the tool may spring in either direction. From the end view you will notice that it has a triangular section with one square corner and two curved ones.

A convenient dimension for this tool is about 21⁄2inches over all from the square to the circular corners. It would be convenient to have a smaller one also, of about 11⁄2inches. The length of this tool should correspond with that of the cutters.

In use, one of the circular corners of the checking tool is forced into the metal, forming a triangular-shaped depression, as shown atb. Two depressions are shown in this sketch in opposite directions to each other, made by holdingthe tool in different positions and using both the circular edges. The object of this operation is to set off the rectangular portionbso that the endsc-ccan be drawn out without disturbing the center.

Fig. 109.—The Fuller.

122. The fuller(Fig. 109) is made with a handle like that of the checking tool, but the portion used for fullering is made circular in section and about 4 inches long. An assortment of sizes should be provided, with diameters of 1, 11⁄2, and 2 inches. When smaller sizes are needed, a bar of round steel may be conveniently substituted. These tools may be properly termed top fullers, because they are generally held on top of the metal and the blows are delivered from above, thus forming depressions on one side only. Sometimes double depressions are required directly opposite to each other. In such cases a short piece of round metal, the same size as the fuller, is placed on the die directly under the top fuller, with the metal between the two.

If the depressions are to be only semicircular, a short piece of half-round material may be provided which is not liable to be dislocated or jarred out of position on the die.

Fig. 110.—The Spring Fullers.

123. The combined spring fullers(Fig. 110) are very convenient for making double depressions. They aresimilar to the single fuller, but are flattened out ataandb, so that they may be opened for various sizes of stock.

Fig. 111.—The Combination Fuller and Set.

124. The combination fuller and set(Fig. 111) may be made with a straight, round handle, but a twisted one is more desirable, because the tool is frequently used in different positions. It should be made of a quality of steel that will withstand severe hammering without becoming battered. The heavy end which forms the tool is made about 11⁄2by 21⁄2inches; the corners on one side are left sharp and square, while those opposite are made quarter-round. One side of this tool may be made almost semicircular if it is intended to be used as a fuller. The length may be about 4 inches.

Fig. 112.—Drawing and Finishing with the Combination Fuller and Set.

This tool is used as a fuller or set in drawing metal between projections which have been formed by using the checking tool. InFig. 112the sections of metal, indicated byaandc, are to be drawn to smaller dimensions. Thiscannot be done with the hammer, because these places are narrower than the width of the hammer dies. Atcthe fuller or set is being used flatwise, which is the better way, because the two round corners will not cause galling. Atait is shown in use edgewise; but this should not be continued after the opening has been enlarged sufficiently to use the tool as atc, unless perfectly sharp corners are desired.

Another convenient use for this tool is for finishing a roughly drawn tapered piece of metal, as atd. Here are shown the roughened tapered surfaces, as they have been produced by the hammer, also the method of using the set. If there is much of this kind of work to be done, it would be advisable to provide a special tool with a circular side which could be used solely as a flatter.

Fig. 113.—The Combined Top and Bottom Swages.

125. The combined top and bottom swages(Fig. 113) are also called spring swages, because they are somewhat flexible at the connecting loop, which keeps them in adjustment. The best material for these swages, on account of the constant hammering to which they are subjected, is a good quality of mild or soft steel. Much hammering has a tendency to crystallize the metal and causes frequent breakage.

The heavy parts forming the swages ought to be well proportioned and made from sufficiently heavy stock. The handles are drawn out from the same material and welded, or merely stub ends may be drawn from thismaterial, and then flat stock welded on to form the handles. In either case the edges should be swaged half-round previous to welding. The top and bottom of the handles are not parallel with the upper and lower parts of the swages, because the heavy parts only should receive hammer blows.

The grooves should be perfect semicircles, with the exception of the edges indicated ate, which should be slightly round, as shown. This prevents metal from becoming lodged in the swages. If the metal sticks, the smith will be unable to revolve it in the swages, and it will become oblong in section. The corners on top of the upper swage should be removed, as shown, so that the blows will be received more directly through its center.

Fig. 114.—The Top and Bottom Swages.

126. The top and bottom swages(AandB,Fig. 114) are made separate, but of the same quality of material as those just described. The handle of the top swageA, however, should be round, with a small portion flattened, as shown. The bottom swageBis constructed with projecting lugsd, as shown. The distance between the lugs should be equal to the width of the lower hammer die, over which the swage should fit closely enough to prevent its displacement. The swages may be used together or separately, as desired, the lower one being convenient for cutting round material, as it prevents marring the sectional form of the stock.

Fig. 115.—The Bevel or Taper Tool.

127. The bevel or taper tool(Fig. 115) is provided with lugs and fits the hammer die. When constructed for general use, the pitch should not be too great, because it may be increased by placing a short piece of metal under one end, as shown, or decreased by inserting metal under the opposite end. The heavy end should be made as nearly perpendicular as possible, with the outer edge of the die. This tool is very handy for drawing any tapering work, such as cold chisels, levers, keys, etc.

128. The V block(Fig. 116) was introduced by the inventor of the steam hammer, and was used instead of a bottom swage. When large, round sections are to be produced, and swages of the proper size are not obtainable, this tool may be used.

Fig. 116.—The V Block.

When round stock is drawn without a swage, only two portions directly opposite to each other are acted on by the hammer, thus causing some liability of producing an oblong section or a hollow centered forging. These difficulties are avoided to a certain extent by the use of the V block, because the force of the blow acts in three directions.

129. The yoke or saddle(Fig. 117) should be made of heavy flat material bent into the form of a U, with the ends perfectly straight and parallel. It should be provided with lugs fitted to the lower die so that both sides will stand erect and at right angles to it, as atA. The distance between the sides may be of any convenient width, 21⁄2inches or more, depending upon the character of the work to bedone. Semicircular depressions should be made on the edges, as shown ate.

Fig. 117.—The Yoke or Saddle.

Another view of the yoke is given atB, with one side removed. As seen here, it is used to draw weldless or solid rings after the stock has been blocked out and a sufficiently large hole has been punched in it to allow it to be hung over the pinp, which rests in the depressions previously mentioned. Hammer blows can be delivered on the exterior of the stock, thus drawing it and increasing its diameter. As this is increased, larger pins should be used, to produce a smoother and more evenly drawn ring.

The yoke, shown atC, is being used as a bridge for drawing the ends of a solid forged jaw. By using it for purposes like this, considerable hand labor may be saved.

Fig. 118.—A,Bolster;B,a Plug Punch in Position for Use.

130. Bolsters or collars(a,Fig. 118) are used for punching holes, upsetting metal for bolt heads, and similar operations. They should be made of soft steel.

131. Punches.—Atb,Fig. 118, a plug punch is shown in position on the metal over a washer or bolster ready for punching. When properly located, a few blows of thehammer will force the punch through the metal and produce a smoothly finished hole.

Notice that the punch is made somewhat tapering, and that the heavier portion is driven through first. Precaution should be taken not to have the punch fit the bolster too closely or be too long, also to have it directly over the hole in the bolster before attempting to drive it through.

Holes can be punched with ordinary handle punches, but care should be taken not to have them too long; even then a bolster or something must be used, so that the punch can be driven clear through the metal and not come in contact with the lower hammer die.

132. Steam Hammer Work.—The following exercises are known as machine forgings. They will require the use of the steam or power hammer and the tools just described. It will be necessary to know beforehand what parts of the work are to be finished, so as to provide a proper allowance at those places. The term “finished” means that the surface is to be removed by the machinist, and the work made smooth and to the required dimensions.

All machine drawings should designate the parts that require finishing, by either the entire word or just the letter “F.” The symbol is more convenient to use for only certain parts, but if the entire forging is to be finished, it may be indicated by “finished all over.”

133. Crank Shaft.—Fig. 119. This is shown without dimensions or finish marks. Select stock sufficiently heavy to produce a forging equal to that shown atb.

Make two depressions with the checking tool, as shown, the distancecbetween them corresponding with thedimensionaon the crank. Draw the ends square and straight on the lower side, as shown atd, then octagonal, and then round. In this way the fillets and shoulders will be equal, as shown ate. The two ends should be swaged smooth and round, then made perfectly straight and at right angles to the crank.

Fig. 119.—Steps in Making a Crank Shaft.

134. Connecting Rod.—Fig. 120. The volume of the material required for sectionemust first be estimated. Then ascertain how many inches of the selected material will be required to give this volume. This will be the distancebfor the fullering shown ata. The sizes of the fullers to be used should be the same as the required radiir. Fuller in the depressions as shown, so that they will correspond with the dimensionsg,h, andlof the finished rod. The metal betweengandhshould then be drawn slightlytapered, as shown in the top view, and to a uniform thicknessl. The small end must now be drawn to the proper size and trimmed with the circular cutter. Make the rod perfectly straight, with the ends parallel to each other and to the rod.

Fig. 120.—Steps in Making a Connecting Rod.

135. Rod Strap.—Fig. 121. This forging is begun by blocking out, as shown atB, withea little greater thanhand plenty of stock atf. The lengthkmust equall, with a slight allowance of surplus metal for the bending operation.

SketchCshows the method of bending. A forming blockmshould be provided for this, the width of which corresponds nearly with the dimensiong, and the thickness is somewhat greater than that atd. The length may be equal to the inside length of the finished strap, but it could be used if shorter. By placing this block perpendicularly on the bottom die, with the forging resting on itand a small piece of metalnfor a blocking on top of that, the upper die may be brought down and a full head of steam turned on while the stroke lever is held down. Both ends can be bent down simultaneously with sledges.

Fig. 121.—Steps in Making a Rod Strap.

After the bending, there may be required more or less labor with the flatter and sledge to square it up in proper shape. Then the ends can be cut off to equal lengths with the hack or hot cutter.

Fig. 122.—Steps in Making an Eccentric Jaw.

136. Eccentric Jaw.—A,Fig. 122. First form the depressioncwith the checking tool; then drawout the enddto the formeand punch a hole atfby using an oblong punch.

Then using the hack, carefully cut from both sides at the places indicated by the broken lines atf. Any fin remaining after the cutting can be removed with a hot cutter or the trimming chisel. The ends forming the jaw can be drawn to the proper size by the use of the yoke. The semicircular ends can also be cut by using the circular cutter, but these ends will require some trimming with a hot cutter, because all the work must be done from exterior sides.

137. Hand Lever.—A,Fig. 123. This illustrates and explains a simple method of stamping which may be extended or adjusted to suit a variety of forgings.

Fig. 123.—Steps in Making a Hand Lever.

In this case two stamping rings are made to suit the work at hand, as follows: If the dimensionhis 2 inches and the thickness of the leveriis1⁄2inch, the rings must be made of3⁄4-inch round stock, and welded to an inside diameter corresponding with the dimensionk.

First draw the material to correspond exactly with the dimensionkin one direction and somewhat greater than that ofhin the opposite. The latter dimension is made larger, to provide some excess metal for the stamping operation, which is done in the following manner: Place one of the rings centrally on the bottom die of the hammer,as shown atB; lay the material on this, with the dimensionhperpendicular and the proper distance from the end to provide enough metal for forming the lever and handle. Then place the other ring on top of the material directly above the lower one, and deliver blows on these rings until the entire thickness almost corresponds with the desired dimensionh. The rings will be forced into the metal and form two depressions, as shown atC. Next with a hot cutter or trimming chisel remove the metal forming the cornerse. Then draw out the lever portion roughly, at first; by using the taper tool a uniform taper can be produced correctly. Cut off the extra stock at the boss, and remove the surplus metal which projects between the bosses as indicated atd, and finish the end smoothly with a common top swage. The handle portion can be formed at the anvil with top and bottom swages after the end has been cut semicircular and to the desired length.

Fig. 124.—Steps in Making a Connecting Lever.

138. Connecting Lever.—A,Fig. 124. After drawing the metal to an appropriate dimension, fuller two depressionsbon opposite sides, the proper distance from the end, to form the jaw. A single bosscshould be stamped with one ring, at the required distance frombto provide the necessary amount of metal for the lengthdof thelever. Then remove the corners, as indicated by the broken lines. Begin drawing the lever by using the combination set, and finish the flat side with the hammer, producing the taper edge with the taper tool. Punch a square hole in the jaw and remove the metal indicated by the broken lines ate, with a hot cutter. Finish the jaw similar to the eccentric jaw and the boss as in the previous exercise.

Fig. 125.—Solid Forged Ring.

139. Solid Forged Ring.—Fig. 125. This should be made of soft steel, the dimensions being supplied by the instructor to suit the stock and equipment at hand. The volume (see calculating rules and tables, pp.197-206) of the forging must first be determined and some surplus allowance for forging provided. The process of making the ring will be found in the explanation of the use of the yoke in section129.

Fig. 126.—Producing Double and Single Offsets.

140. Double and Single Offsets.—Fig. 126. The following exercises are given to explain the use of simple appliances for producing work accurately and rapidly. Examples similar to the four following ones would require considerablecare and skill if they were to be produced without the use of the steam hammer.

Atais shown a double offset bend, the depth of which, for illustration, may be1⁄2inch. To produce this, place two pieces of1⁄2-inch flat material, withwidth correspondingto that of the material to be bent, on the lower die, and sufficiently far apart to allow the offsets to form between them. On these the material is placed, and on top of that also, located midway between the1⁄2-inch supporting pieces, a third piece of1⁄2-inch stock is placed. The width of this should correspond with the required dimension ataand should be somewhat longer than the width of the material to be bent. This arrangement is shown atc. By delivering a sufficiently heavy blow upon them, the two offsets, will be formed simultaneously and accurately.

Fig. 127.—Simple Methods for Bending Clamps with a Steam Hammer.

In all operations of this kind the thickness of the lower forming pieces should always correspond with the required depth of the offset, and the corners should be ground round to prevent shearing or galling.

Atdis shown a single offset which can be produced in a similar way, with the exception that here only two blocks are required. But the forming corners of theseshould also be ground as previously stated, and they are placed in position as shown ate.

Figure127shows the method of bending a semicircular pipe or rod clamp. Here a piece of round stockfis used above for stamping, but as the lower blocks are easily displaced, it would be advisable to make a stamping block like that shown atg. This could be used instead of the two lower pieces. If the clamps were to be made square, then the stamping block should be like the one shown ath, and the upper piece as atfshould be made square.

Questions for Review

What is a forging? Name the machines used in making forgings. Who invented the steam hammer? How should material be held on the dies? What tool is used in place of a hot cutter at the hammer? How can a convex end be produced? Describe the special form of a trimming chisel. How should metal be broken after it has been nicked with the cold cutter? Describe the correct way of using a hack in cutting square stock. Explain the use of a checking tool. Describe the different fullers used at the hammer. Explain their uses. For what is a combination fuller and set used? Describe the hammer swages. The bevel or taper tool. What is it used for? What is the advantage in the use of the V block? Describe the yoke. Explain its use. What is the difference between a plug punch and a handle punch? How is a bolster used for punching? What does the word “finished” mean on a drawing? What hammer tools are brought into use in making a crank shaft? In making the connecting rod? Describe how the hammer is used in bending a rod strap. What tools are brought into use in making the eccentric jaw? Describe the method of forming the bosses on the hand lever. Explain some simple methods of bending work with the steam hammer.

141. Art Smithing.—This subject might appropriately be considered a separate branch, because many smiths, who really deserve the credit of being excellent mechanics, have never become proficient in this particular line of work.

Art smithing is the highest development of metal work. The best art smiths are foreigners, as European countries use much more of this kind of work for decoration than this country does. The greater part of this work is entirely too difficult for the average student unless it is attempted with the assistance of machinery.

It is possible, however, to do a certain amount of scroll work with accuracy and make simple decorative pieces. One should commence with the design of the article to be made. The harmonious combinations of straight and curved lines and their adaptation for different purposes should be studied. The study of design will not be taken up here, but several examples which will furnish a basis for further work along this line are given for consideration.

Designing may be done on any convenient material such as paper, wood, or blackboard. The last is preferable because confusing marks can easily be erased. A sketch thus made may be used as a working drawing. If the design is to be used many times, a very convenient and substantial method is to reproduce it on a piece of shellackedpine board, and then paint it on in solid form. When this is dry, a few more coats of shellac should be applied to preserve it. If desired, the length of each individual scroll may be indicated.

There are various methods of obtaining the different lengths: by placing a strong string over the scroll and then measuring the string; by using a piece of soft wire in the same manner, lead wire being preferred; or by the following method:—

Take a piece of1⁄8-inch material 3 or 4 feet long, mark it lightly on both edges into equal spaces either 3 or 6 inches long, and stamp the feet or inches upon it with steel figures. After this is done, a small rolling curl, as shown inFig. 129, should be formed, and the entire length bent on the scroll former while the material is cold. This is the manner, minus the markings mentioned, in which all scrolls are to be formed. This product with the markings upon it should be kept for ascertaining the number of inches required for either large or small scrolls. Always place the curled end of this measure in position on the working drawing and adjust it until it conforms to the outline of the design. Then place a crayon mark on both the drawing and the measure where they cease to correspond; the length of that portion which corresponds can be ascertained from the markings on the measure, and all remaining irregular curves can be measured by a string, wire, or rule. This measure will prove also to be quite a satisfactory and accurate means of arranging new designs.

142. Scroll Fastenings.—There are three different methods used for joining scrolls: welding, riveting, and banding with clips. The first is the most difficult and the most artistic, but unless one is quite expert at welding,especially in joining light material such as is generally used for scroll work, it would perhaps be better to disregard this method entirely.

Riveting presents a very neat appearance and makes the product quite strong and substantial, but unless the marking and drilling of holes is accurately done, the result presents a distorted and ill-shaped combination, which cannot be remedied without drilling new holes.

It would be advisable, then, to adopt the last method generally, resorting to riveting wherever it is impossible to use clips or bands, or where strength is an essential requirement. If a clip is misplaced, it can be replaced with a new one, or it may be moved into the proper position without showing that an error has been made.

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