ToolsTemperature (Fahr.)DegreesColorScrapers for brass430Very pale yellowLight turning tools430Very pale yellowLathe and planer tools for steel430Very pale yellowSteel engraving tools430Very pale yellowMilling and boring cutters460Straw yellowScrew-cutting dies460Straw yellowTaps and reamers460Straw yellowPunches and dies480Dark strawPenknives480Dark strawTwist drills500BronzePlane irons500BronzeSurgical instruments530Dark purpleCold chisels for steel540Dark purpleCold chisels for cast iron550Dark blueCold chisels for wrought iron550Dark blueSprings570Very dark blue
Suitable Temperature (Fahr.) for:
DegreesAnnealing tool steel900Forging tool steel1200 to 1500Hardening tool steel1200 to 1400Casehardening iron or soft steel1300 to 1500
Colors and Corresponding Temperatures (Fahr.) for Iron
Bright red in dark750 to 760Red hot in twilight880 to 890Dark red hardly visible in daylight970Red visible by daylight1070Brighter red by daylight1300Cherry red by daylight1450Bright cherry red by daylight1650Light cherry red by daylight1800Orange2000Yellow2150White heat2350White welding heat2600White welding and dazzling2800
Questions for Review
What is meant by the carbon contents of steel? Why is steel graded according to its carbon content? Explain the cause of fire cracks. How can they be prevented? Why should steel be thoroughly healed? If steel is overheated or burned, what is the effect? Why should steel never be left in the fire to soak up heat? How does steel forge if it is unevenly heated? How should the blows be delivered in forging steel? What is annealing? Describe three methods of annealing. Is it best to anneal cold chisels and lathe tools? Explain the process of hardening steel. What effects does hardening have? Are the forging and the hardening heats the same? Why is steel polished after it is hardened? Explain the process of tempering. What is the effect of tempering? How may the heat be supplied for tempering? Name the colors in order as they appear in heating steel. Explain the methods of hardening and tempering. Why should a cold chisel be kept in motion when it is being hardened? What is meant by oil-tempering? What is meant by casehardening? Explain different methods of casehardening.
What is meant by the carbon contents of steel? Why is steel graded according to its carbon content? Explain the cause of fire cracks. How can they be prevented? Why should steel be thoroughly healed? If steel is overheated or burned, what is the effect? Why should steel never be left in the fire to soak up heat? How does steel forge if it is unevenly heated? How should the blows be delivered in forging steel? What is annealing? Describe three methods of annealing. Is it best to anneal cold chisels and lathe tools? Explain the process of hardening steel. What effects does hardening have? Are the forging and the hardening heats the same? Why is steel polished after it is hardened? Explain the process of tempering. What is the effect of tempering? How may the heat be supplied for tempering? Name the colors in order as they appear in heating steel. Explain the methods of hardening and tempering. Why should a cold chisel be kept in motion when it is being hardened? What is meant by oil-tempering? What is meant by casehardening? Explain different methods of casehardening.
91. Tongs.—As tongs are among the most important tools and quite difficult to make, they will be taken up in this chapter on tool making.
The weakest places in a pair of tongs are where the shoulders or offsets are formed for the jaws and handles. These places should be reënforced by fillets as large as the usefulness and appearance of the tongs will permit; they should never be made sharp and square, unless their construction demands it.
All tongs for general blacksmithing can be forged properly with the hand hammer and the use of such tools as the top fuller, the swages, and the round-edged set hammer. Some assistance with a light sledge will be necessary. The use of such tools as a square-edged set or the file for forming shoulders or fillets is very objectionable, especially in the hands of unskilled workmen. If the two parts do not seem to fit as they should, due to the fillets which are present, they will generally adjust themselves when they are riveted together, heated, and worked freely.
92. Heavy Flat Tongs.—Fig. 74. Fullering, forging, swaging, punching, and riveting. Material: 15 inches of7⁄8-inch square mild steel.
Mark the center of the 15-inch length with a hardy or cold chisel. Form two depressions3⁄8inch deep, with atop fuller, one 2 inches from the end ata, the other 3 inches from the same end but on the opposite side. Form a third depression to the same depth, but at an angle of 45 degrees, starting from the bottom of the first one, and on the side indicated by the broken line, as atb. Draw the 2-inch end to 1 ×1⁄2inch froma, tapering to 1 ×3⁄8inch at the end. This portion forms one jaw, as shown atc. Now flatten out about 2 inches of the metal from the beveled depressionbtoward the center mark, to9⁄16inch thick, allowing the metal to spread as wide as possible. This should then be forged and formed into shape for the jointd, and the fuller again placed in the second depression to make the dimension there5⁄8inch, as shown atd.
Fig. 74.—Steps in Making Heavy Flat Tongs.
Fig. 74.—Steps in Making Heavy Flat Tongs.
Forge the other end in the same manner, exerting due care to have all dimensions correspond; cut the stock in two at the center. Draw out the heavy ends for the handles with the power hammer or with some assistance from a sledge. They should be roughly forged at first with an allowance for finishing as follows: Beginning at the joint, use the top and bottom swages on the outer edges through the greatest width, and swage to5⁄8×1⁄2inch. This swaging should be continued toward the end to form the handle. By using the flatter during the swaging, the sides may be kept straight, smooth, and slightly tapering to a round section. Make the end3⁄8inch in diameter for a length of 3 inches. SketchFshows one side of a pair of tongs drawn and swaged.
Place the parts together to see if they fit properly; if they do not, make the necessary alterations. Use a top fuller to form a grooveeabout1⁄8inch deep, lengthwise on the inside of the jaws, and smooth the sides and edges with a flatter. Then punch a3⁄8-inch hole in the center of the joint, as shown in sketchF. This should be done on both parts.
Heat thoroughly the end of a3⁄8-inch rivet, 13⁄4inches long, and with it rivet the two portions tightly together. Heat the tongs, make them work freely, and adjust them to hold3⁄8-inch flat iron, with the entire length of the jaws in contact and with the ends of the handles 1 inch apart. The jaws and handles should be adjusted so that a line extended lengthwise across the center of the rivet would pass midway between them.
93. Light Chain Tongs.—Fig. 75. Forging, swaging, punching, fullering, and riveting. Material: 13 inches of3⁄4-inch square mild steel.
Fig. 75.—Steps in Making Light Chain Tongs.
Fig. 75.—Steps in Making Light Chain Tongs.
Mark the center of this length with a hardy or cold chisel. Form a shoulder 11⁄4inches from the end, and draw this end to7⁄8×1⁄2inch at the bottom of the shoulder, tapering to3⁄4×3⁄8inch at the end, as ata. Form a second shoulder at an angle of 45 degrees, starting from the bottom of the first one, by holding the work on the anvil, as shown atb. The blows should be directed a little toward the center mark, to flatten and spread the metal for forming the joint of the tongs. Form a third shoulder atc, 1 inch from and on the opposite side to the first and toward the center mark, the thickness here being1⁄2inch. Note that these shoulders should be made with overhanging blows and not by using the fuller. The metal between the shoulderscandashould now be forged into shape for the joint. Forge the other end in a similar manner, being careful to have all dimensions correspond; then cut the stock in two at the center.
Draw out the heavy ends for the handles with a powerhammer or with some assistance from a sledge. Roughly forge them from1⁄2×7⁄16atc, down to5⁄16inch round, 3 inches from the end. Finish the edges by using the top and bottom swages. By using the flatter on the sides during the swaging, the handle may be kept straight, smooth, and slightly tapered to where it terminates into round. SketchFinFig. 74shows the handle drawn out and swaged.
Fig. 76.—The Completed Light Tongs.
Fig. 76.—The Completed Light Tongs.
Place the two parts together to see if they fit properly; if they do not, make the necessary alterations. Taking each piece separately, perform the following operations: Fuller a groove1⁄8inch deep, lengthwise on the inside of the jaw, and another crosswise about1⁄4inch from the end as shown atA,Fig. 76. Then punch a5⁄16-inch hole in the center of the joint. A5⁄16-inch rivet 11⁄2inches long should be obtained, its end should be thoroughly heated, and the two parts riveted tightly together. Heat the tongs and make them work freely; adjust them to hold3⁄16-inch flat iron with the full length of the jaws in contact, also to hold3⁄8-inch round material in the cross groove when the handles are 1 inch apart. They should be adjusted, so that if a line were extended lengthwise through the center of the rivet, it would pass midway between the jaws andhandles. When complete these tongs will appear as inFig. 76.
94. Lathe Tools.—A complete description of lathe tools would require too much space in this book, therefore only six common ones will be explained; by applying the knowledge received from making these, the operator should be able to forge many others. These with the other tool steel exercises should supply sufficient practice in forging, hardening, and tempering tool steel.
If these tools are to be put into practical use, a good quality of tool steel should be provided, cut about 8 inches long for each one, and great care should be taken in the heating, forging, and tempering. If, however, they are to be made for practice alone, then much shorter pieces may be conveniently used, also an inferior grade of steel; mild or soft steel would be sufficiently good to provide the needed practice in heating, forging, and tempering. Even though the material is inferior, the operations should receive the most careful attention.
The material may be 1 ×1⁄2-inch,7⁄8×3⁄8-inch, or any suitable stock size.
Fig. 77.—Brass Tool.
Fig. 77.—Brass Tool.
95. Brass Tool.—Fig. 77. Forging, hardening, and tempering. Material: 6 to 8 inches of1⁄2× 1-inch tool steel.
Starting about3⁄4inch from one end, draw to a uniformtaper on both sides and on one edge only, so that the metal is1⁄4inch thick and1⁄2inch wide at the end. The lower or beveled edge also should be drawn thinner than the upper to provide the necessary clearance amounting to about 5 degrees on each side, as shown in the sectional view. The end should be cut off at an angle of 70 degrees and ground semicircular in form with the necessary clearance.
Heat about 2 inches of this end and harden in the manner described for the cold chisel, but in this case the color for tempering is a very pale yellow.
96. Cutting-off or Parting Tool.—Fig. 78. Fullering, forging, hardening, and tempering. Material: 7 inches of1⁄2× 1-inch tool steel.
Fig. 78.—Cutting-off or Parting Tool.
Fig. 78.—Cutting-off or Parting Tool.
With a top fuller form a depression across one side5⁄8inch from the end, fullering the metal to3⁄16inch thick. Draw this end down to 1 ×3⁄16inch. The thickness of the metal where it was fullered should also be decreased to1⁄8inch, gradually increasing to3⁄16inch at the end, taking extreme care to have sufficient clearance from front to back and from top to bottom. The cutting edge is generallyallowed to project about1⁄8inch above the stock; the end is trimmed off at an angle of 75 to 80 degrees and ground, as shown inFig. 78, after which it is hardened and tempered to a pale yellow.
97. Heavy Boring Tool.—Fig. 79. Drawing, bending, hardening, and tempering. Material: 7 inches of1⁄2× 1-inch tool steel.
Fig. 79.—Heavy Boring Tool.
Fig. 79.—Heavy Boring Tool.
Draw about 21⁄2inches tapering to1⁄2inch square at the end; the taper on the top edge should be only1⁄8inch, while that on the bottom should be3⁄8inch, as shown ata. With the metal resting flat on the anvil and the top edge to the left, bend down3⁄4inch of the end to an angle of about 80 degrees, then forge down the corners from the point back to the heel, to a slight octagonal form, as shown inFig. 79. Grind the projecting end of the angle semicircular with a clearance of 15 degrees, then harden and temper to a pale yellow.
98. Light Boring or Threading Tool.—Fullering, drawing, hardening, and tempering. Material: 5 inches of1⁄2× 1-inch tool steel.
Using a top fuller, form a depression7⁄16inch deep on one edge and 2 inches from the end. Draw this metal slightly tapering to7⁄16inch square at the end, keeping it straight on the top. With the metal resting flat on the anvil and the straight edge to the left, bend down3⁄4inch of the end to an angle of 80 degrees, then forge the corners between the angle and where the depression was formed to a slight octagonal form.
For a boring tool, grind the projecting end of the angle semicircular in form, with sufficient clearance for boring a hole of the desired size; for a threading tool grind it to the proper angle of the thread with sufficient clearance, then harden and temper it to a pale yellow.
99. Diamond Point Tool.—Fig. 80. Forging, hardening, and tempering. Material: 7 inches of1⁄2× 1-inch tool steel.
Fig. 80.—First Steps in Making a Diamond Point Tool.
Fig. 80.—First Steps in Making a Diamond Point Tool.
Using a top fuller, form a depression3⁄8inch deep on one edge3⁄4inch from the end, as ata. Then holding the depression over a round edge of the anvil and deliveringblows on the end, as indicated atb, forge the3⁄4-inch end into a square form, at an angle of 70 degrees to the lower edge of the stock, as shown atc. By resting the inner corners of this end on the face of the anvil and delivering blows on the opposite outside corners, as shown inFig. 81, its form should be changed to7⁄16inch square, projecting diagonally from the stock, as shown ata,Fig. 82.
Fig. 81.—Changing the Form ofc,Fig. 80, to that ofa,Fig. 82.
Fig. 81.—Changing the Form ofc,Fig. 80, to that ofa,Fig. 82.
Fig. 82.—Diamond Point Tool, Finished.
Fig. 82.—Diamond Point Tool, Finished.
By using a sharp, hot cutter and cutting entirely from the right inside surface (a,Fig. 82), and by holding the point over the edge of the anvil, so that the operation will have a shearing effect, the excess metal which extends more than3⁄8inch above the upper line of the stock may be removed. For a right-hand tool the point should be set1⁄8inch to the left, as shown atb, the two outside surfacesbeing ground smooth and forming an acute angle; the inside portion of the end on the side indicated byashould be ground somewhat shorter, producing a diamond-shaped appearance. Harden and temper to a very pale yellow.
Reverse the operations of cutting, setting, and grinding for a left-hand tool.
100. Right Side Tool.—Fig. 83. Forging, offsetting, hardening, and tempering. Material: 7 inches of1⁄2× 1-inch tool steel.
Fig. 83.—First Steps in Making the Side Tool.
Fig. 83.—First Steps in Making the Side Tool.
Fig. 84.—Side Tool.
Fig. 84.—Side Tool.
Heat and cut off about5⁄8inch of one corner, as ata,Fig. 83, and form a depression with the top fuller 11⁄2inches from the end on the side indicated atb,1⁄4inch deep at the upper edge, leaving the metal full thickness at the lower edge. Then the metal should be roughly spread out from the upper edge of the stock by holding the fuller lengthwise, as shown atC, leaving the lower edge the full thickness,and smoothed with a flatter, drawing the upper edge to1⁄8inch in thickness. The above operations could be done with a hand hammer, but not without considerable hard work.
Fig. 85.—Offsetting the Side Tool for Clearance.
Fig. 85.—Offsetting the Side Tool for Clearance.
Trim this end to the form shown inFig. 84, by using a sharp, hot cutter and cutting entirely from the side indicated byd. When this has been done correctly remove all metal extending more than1⁄4inch above the upper edge of the stock. When this has been forged to the correct shape, heat and place the tool so that the fullered shoulder is just beyond the edge of the anvil, then form the offset with a round-edged set hammer, as shown inFig. 85. Grind the upper edge parallel with the stock but at a slight angle, to produce a cutting edge, and grind the face side straight and smooth. In cooling this tool for hardening it should be placed in the water, as shown inFig. 86, to insure hardening the whole cutting edge. Leave sufficient heat in the heel or bottom of the tool to draw the temper uniformly to a pale yellow.
Fig. 86.—Hardening the Side Tool.
Fig. 86.—Hardening the Side Tool.
101. Forging Tools.—The following forging tools aresomewhat smaller than those used in general smith work, but they are perfectly serviceable and sufficiently heavy for manual training or considerable ordinary work. The material for their construction should be tool steel of 0.80 to 0.90 per cent carbon, 11⁄4inches square, unless otherwise specified. The holes or eyes should be punched straight, and the precautions formerly given under the head of punches should be observed.
A tapered drift pin of an oval section7⁄8×5⁄8inch at the largest end, also a smaller oval-shaped handle punch, should first be provided.
102. Cold Chisel.—Fig. 87. Forging, hardening, and tempering tool steel. Material: 61⁄2inches of3⁄4-inch octagonal tool steel.
Fig. 87.—Cold Chisel.
Fig. 87.—Cold Chisel.
First draw1⁄2inch of one end to a smooth, round taper about3⁄8inch in diameter at the extreme end, then grind off the rough projecting edges until it is1⁄2inch in diameter. This end should not be cooled quickly, because it might harden somewhat, which would cause it to break easily. Starting 2 inches from the opposite end, draw the tool tapering to1⁄8inch thick and 1 inch wide, using the flatter on these tapered sides and edges. They should be madestraight and smooth, with the edges perfectly parallel. Two views with dimensions are shown inFig. 87.
Grind the cutting edge of the chisel to the desired angle, then harden and temper it as follows: Heat about 2 inches of the cutting end to a dull cherry red and plunge about 1 inch of this perpendicularly into water; withdraw it about1⁄2inch, and keep it in motion between the first and second cooling places until the end is perfectly cold. Remove the tool and quickly polish one side with emery cloth or sandstone, watching the varying colors as they make their appearance and move toward the edge; when the dark purple or blue color entirely covers the point, thrust it into the water again and leave it there until thoroughly cooled. Regrind cautiously, protecting the temper, and test its cutting qualities on a piece of cast iron or soft steel.
103. Hot Cutter.—Figs.88and89. Punching, fullering, forging, hardening, and tempering. Material: 4 inches of 11⁄4-inch square tool steel.
Fig. 88.—Steps in Making the Hot Cutter.
Fig. 88.—Steps in Making the Hot Cutter.
Fig. 89.—Hot Cutter.
Fig. 89.—Hot Cutter.
Punch and drift an eyehole 13⁄4inches from the end, making all sides straight and smooth, as shown ata,Fig. 88. With a pair of3⁄4-inch fullers, form two depressions on opposite sides1⁄4inch from the eye,as atb, fullering the metal to5⁄8inch thick. From this place draw the end tapering to 11⁄2×1⁄8inch, and trim it off at a right angle to the stock, as atc. Using a hot cutter and working equally from all sides, cut the tool from the bar 11⁄4inches from the edge of the eye. Draw the head end tapering to about7⁄8inch from the eye, draw the corners to form a slightly octagonal section. Remove all projecting metal so as to produce a convex head. (SeeFig. 89.) This will be referred to later as forming the head. Grind both sides of the cutting end equally to form an angle of 60 degrees, with the cutting edge parallel to the eye. Harden, and temper to a dark purple or blue.
104. Cold Cutter.—Figs.90and91. Punching, forging, hardening, and tempering. Material: 4 inches of 11⁄4-inch square tool steel.
Fig. 90.—Steps in Making the Cold Cutter.
Fig. 90.—Steps in Making the Cold Cutter.
Fig. 91.—Cold Cutter.
Fig. 91.—Cold Cutter.
Punch and drift an eye 2 inches from the enda,Fig. 90. Draw this end tapering on the sides parallel with the eye, forming convex surfaces and terminating in 1 ×3⁄16inch. (Seesketchesbandc.) Cut the tool off atc, 11⁄4inches from the eye, and form the head.
Grind the cutting end equally from both sides to form an angle of 60 degrees, and a convex cutting edge similar to that shown atd. Harden, and temper to a dark purple or light blue. The finished tool is shown inFig. 91.
Fig. 92.—Square-edged Set Hammer.
Fig. 92.—Square-edged Set Hammer.
105. Square-edged Set.—Fig. 92. Punching and forging. Material: 31⁄2inches of 1-inch square tool steel. Heavier or lighter stock may be used if desired.
Punch and drift an eye 11⁄4inches from the end, then, using a pair of3⁄8-inch fullers, form depressions about1⁄8inch deep across the corners, as ata,Fig. 92. Cut the tool off 11⁄2inches from the eye, and form the head to3⁄4inch at the end. Heat and anneal in warm ashes; when it is cold, grind the face smooth, straight, and at right angles to the stock.
106. Hardy.—Fig. 93. Fullering, forging, hardening, and tempering. Material: 3 inches of 2 ×7⁄8-inch tool steel.
Using steel 2 inches wide with a thickness equal to the dimension of the hardy hole, fuller and draw a slightly tapered shank 13⁄4or 2 inches long, to fit loosely into the anvil. The broken lines ata,Fig. 93, indicate the drawn shank. Cut off the stock 11⁄2inches from the shoulders atb. Heat and drive the drawn end into the hardy holeso as to square up the shoulders and fit them to the anvil. Then draw the heavy end tapering gradually from the sides, terminating1⁄8inch thick and 2 inches wide. Grind this tool similar to the hot cutter; harden, and temper to a purple or blue.
Fig. 93.—Hardy.
Fig. 93.—Hardy.
Fig. 94.—Flatter or Round-edged Set Hammer.
Fig. 94.—Flatter or Round-edged Set Hammer.
107. Flatter.—Fig. 94. Upsetting, forging, and punching. Material: 43⁄4inches of 11⁄2-inch square tool steel.
In forming the face of a flatter, the metal should be upset. This may be accomplished by ramming, but when so done, excess metal is formed just above the wide portion, causing considerable fullering and forging. If a piece of steel 43⁄4inches long and 11⁄2inches square is cut off, and one end is drawn slightly tapering, it may, when heated, be placed in a square hole of the right size in the swage block, with the drawn end supported on something solid, leaving 11⁄2inches projecting. Thehot steel can then be hammered down with a couple of sledges, until the face is formed to3⁄8inch thick or about 2 inches square, as ata,Fig. 94.
Punch and drift an eyehole 11⁄4inches from the face, then draw and form the head. Anneal in warm ashes. When it is cold, the face should be ground perfectly straight, smooth, and at a right angle to the body, with the surrounding edges slightly round, as shown, or they may be left sharp and square if desired.
A round-edged set hammer may be made in this manner, but as the face should not be so large, less metal is required.
108. Small Crowbar.—Fig. 95. Drawing, swaging, welding, and tempering steel. Material: 16 inches of3⁄4-inch square mild steel, also a small piece of tool steel.
Fig. 95.—Steel-faced Crowbar.
Fig. 95.—Steel-faced Crowbar.
Draw 11 inches to the following dimensions: the first 4 inches to3⁄4-inch octagon, then beginning with3⁄4-inch round gradually reduce to1⁄2-inch round at the end. This should be smoothly forged and swaged.
Form a depression1⁄4inch deep on one side of the square portion 2 inches from the end; from this, draw the metal to1⁄2×3⁄4inch; by using a hot cutter where the depression was made, split and raise up a scarf fully3⁄4inch long, as shown in the sketch. Prepare a piece of tool steel 21⁄2×3⁄4×1⁄2inches; on one end of this draw a long, thin scarf androughen it with a hot cutter, so it can be held in place securely. (SeeFig. 95.)
Heat the bar cautiously where the scarf was raised, to avoid burning it; slightly cool the tool steel and put it into place. By holding the piece of steel against a hardy, swage, or fuller, the scarf can be hammered down tightly over the tool steel, which should hold it securely for heating. Place the pieces in the fire and heat them to a red; remove and thoroughly cover them with borax; replace them and raise the heat to a bright yellow or welding heat.
While the first light blows for the welding are being delivered, the end should be held against something to prevent the steel from being displaced; when positive that welding is proceeding, make the blows heavier and complete the operation.
When the pieces are securely joined, cut off the corner opposite to the steel face, and draw the bar tapering from this side, to a sharp, flat edge 1 inch wide. Bend this through its smallest dimensions to an inside radius of about 31⁄2or 4 inches and with the edge extending1⁄2inch to one side of the bar, as inFig. 95. File or grind the outside surface and edge of this; then harden, and temper to a blue.
109. Eye or Ring Bolts.—An assortment of eyes is shown in Figs.96,97, and98. All eyes should possess two essentials: the necessary strength and a good appearance; therefore the method of making should be chosen to fulfill those requirements. Generally the eyes that have the most strength require the greatest amount of labor.
A,Fig. 96, is an open eye which is very easily made, because bending is the only operation required. Themethod of making this form of eye has already been explained in section69.
Fig. 96.—Eye or Ring Bolts.A, an open eye;B, a welded eye.
Fig. 96.—Eye or Ring Bolts.A, an open eye;B, a welded eye.
Bis a welded eye. It is made by forming first a flat, pointed scarf on the end of the bar and bending it through its smallest diameter where the drawing was begun. This bend should be no less than 70 degrees on the outer side. Determine the length of the material needed for forming a ring of the required diameter, then subtract the diameter of the material from the determined length. Using this result, place a center-punch markfthat distance frome, and bend the piece atfin the same direction ase.
Form the metal between the bends into a circle, and place the scarf in position for welding, as atB. During the heating for welding, if the circle heats more rapidly than desired, it should be cooled off and the heating then continued. The welding should be done as quickly as possible and swaged if required.
The eye bolt, shown inFig. 97, is similar to a solid forged eye. It is formed and welded with a specially forged scarf called a butterfly scarf.
Determine the amount of material needed to form a ring of the required diameter, and add to that a sufficient allowance for upsetting and welding, which would be approximately equal to the diameter of the material used. An invariable rule for that allowance cannot begiven, because the results of the upsetting are seldom the same.
Place a center-punch mark the estimated distance from one end of the bar; then upset the end1⁄8inch larger than its original diameter, next upset it at the mark to a similar dimension, and bend it there to an angle of no less than 70 degrees. Now with the bend lying flat on the face of the anvil, draw out a thin, narrow scarf with a small ball peen hammer, not any wider than the thickness of the metal. The scarf may be drawn also by holding the outer portion of the bend on a sharp corner of the anvil and by drawing with overhanging blows. This scarf is shown in the upper view ofFig. 97as it should appear.
Fig. 97.—Eye Bolt made with a Butterfly Scarf.
Fig. 97.—Eye Bolt made with a Butterfly Scarf.
The butterfly scarf should now be formed on the opposite side from the one just finished, by holding each side of the end at an angle of about 45 degrees on the edge of the anvil; this scarf may be drawn with overhanging blows. The extreme end should also be drawn thin in a similar manner, while it is held at a right angle with the edge of the anvil. All outer edges of this scarf should be thin and sharp.
Bend the metal into a circle and place the scarfs in position, as shown atC, having all edges overlapping slightly and hammered down into close contact. Heat the work for welding, observing the precaution given in the explanation of the former eye. In welding, deliver the first few blows uprightly on each side, then weld the edges of thescarfs with the ball of the hammer. A few careful experiments with these scarfs will show what is required, and with practice no more labor will be needed than is required for the previous eye. The finished product will be more substantial and presentable.
Fig 98.—D,a Ship-smith Eye;E,a Solid Forged Eye.
Fig 98.—D,a Ship-smith Eye;E,a Solid Forged Eye.
D,Fig. 98, is generally called a ship-smith eye, because it is commonly used in ship work where strength is essential. Special swages, convex lengthwise, are usually provided for shaping the concave curves where they are formed and welded. The eye should be circular between the places indicated byfin sketchD, and the lines fromfto where it is welded should be as nearly straight as possible, to increase the strength.
In estimating the material, take two thirds of the length for a ring of the required diameter, and add to that the proper allowance for the stock which forms the portion fromfto the weld, and also an amount sufficient for the scarf. This scarf is drawn similar to the one for the welded eye inFig. 96, but it should be made convex through its smallest dimension with a top fuller, whose diameter is equal to that of the metal. This is done while the metal is held in a bottom swage of corresponding size. When the scarf is finished, bend the eye into shape and bring the scarf close up to the stem of the eye.
Heat and weld with swages; if convex swages are not obtainable, others may be used by taking care to preventmarring the curves. This eye may also be welded with a large fuller while it is held over the horn of the anvil. If the curves are severely marred, the strength of the eye is lessened.
A solid forged eye is shown atE. When eyes like this are drop-forged in special dies, as they generally are, they do not require much skill, but when made entirely by hand they require considerable experience.
In forging an eye of this kind, the volume of material needed must first be determined, making some extra allowance for the usual waste. A convenient size of material should then be selected (round is preferable) and the amount required for the eye marked off. The round stem should be drawn down to size and the part for the eye forged to a spherical shape, then flattened, punched, and enlarged to correct dimensions.
110. Calipers.—The calipers shown inFig. 99may be easily made from the dimensions given;3⁄4×1⁄8-inch stock should be used for the main piece, and1⁄2×1⁄8-inch stock for the legs.
111. Stock Calculation for Bending.—In the expansion and contraction of metals during the operation of bending, there is a fixed line, where the metal is left undisturbed; in other words, where it is not increased or decreased in length. So all measurements taken to determine the length of material required for producing any bent shapes should be taken from that fixed or undisturbed location, in order to attain accurate results.
All materials which have a symmetrical cross section, such as round, square, octagonal, oval, or oblong, have the above line at their true centers, no matter which way they are bent. While the metal remains undisturbed at thecenter of any of the above sections, the rest of it undergoes a change; the inner portion, in the direction of bending, will contract and become thicker, and the outer portion will expand and become thinner.