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.
CHAPTER V
Tool Making and Stock Calculation
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 of 7⁄8-inch square mild steel.
Mark the center of the 15-inch length with a hardy or cold chisel. Form two depressions 3⁄8 inch deep, with a top fuller, one 2 inches from the end at a, 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 at b. Draw the 2-inch end to 1 × 1⁄2 inch from a, tapering to 1 × 3⁄8 inch at the end. This portion forms one jaw, as shown at c. Now flatten out about 2 inches of the metal from the beveled depression b toward the center mark, to 9⁄16 inch thick, allowing the metal to spread as wide as possible. This should then be forged and formed into shape for the joint d, and the fuller again placed in the second depression to make the dimension there 5⁄8 inch, as shown at d.