42. The hack saw ([Fig. 21]) is at present considered a necessary part of any forge shop equipment. It is used for sawing iron or untempered steel, and when a power shear is not included in the equipment, considerable filing can be saved by sawing. The frame illustrated is adjustable so that the blades can be made of different lengths and be set at right angles to the frame, which is sometimes convenient.
When using the hack saw, make slow, full-swing strokes; when drawing back for another stroke, it will prolong the efficiency of the blades if the saw is raised up to prevent the teeth from bearing on the metal, as the backward stroke is more destructive to the teeth than the forward or cutting stroke. The blades are made from 8 to 12 inches in length, 1⁄2 inch in width, and with from 14 to 25 teeth to the inch. They are tempered so hard that they cannot be filed, but are so inexpensive that when they cease to be efficient they may be thrown away.
Fig. 21.—The Hack Saw and Files.
43. The files ([Fig. 21]) are illustrated merely to show that they are to be used for special purposes. As finishing or filing is almost a trade in itself, the file should not be used in blacksmithing, unless it is especially necessary. A piece of smith’s work that has been roughly forged is much more admirable than a highly polished piece that has been filed into elegance.
Files are round, flat, square, half round, and of numerous other shapes, and vary in lengths and cuts for rough or smooth filing. Any of them may be used as required, but it should be remembered that filing is not blacksmithing.
Questions for Review
What is the main difference between the old type of smithing forge and a modern one? How is the air supplied for each? What is a tuyère iron? Describe the hearth. What kind of coal is used for forging? Is coal the best fuel for heating all metals? Why is charcoal the best fuel for heating carbon steel? How should the fire be built to prevent making excess smoke? What other fuel is used in forging? What kind of work is it used for? Describe the different parts of the anvil. How is a cast-iron anvil hardened? How is a wrought-iron anvil hardened? Name and describe the different kinds of hammers. Why should the tongs fit properly the iron to be handled? Name and describe the different tongs you have been made familiar with. How would you secure the tongs to relieve the hand?
What is a hardy? What is it used for? Explain the proper method of using it. Is it always good practice to use a hardy for marking the iron? Why? What is the difference between a cold and a hot cutter? What is the general use for a flatter? Should it be tempered? Why? What are set hammers? What is a punch used for? Explain the difference between a hand punch and a handle punch. When punching a heavy piece of metal, how is the tool prevented from sticking fast? Are all punches tempered? Why? Describe and explain the use of top and bottom swages. How should the bottom swage be placed for use? What is meant by water swaging? State the effect it has on the iron. What are top and bottom fullers used for? Are they always used in pairs? How is the bottom one placed for use? What are the button head set and heading tool used for? What is the special advantage of having a swage block? Explain some of the different uses of that tool. What is the special use of the surface plate? What is the tapered mandrel used for? Are all mandrels of this particular kind? Explain others. Is it good practice to use the vise for bending? Why? Describe the cold chisel. Should all cold chisels be made alike? What is the center punch used for? Describe the other bench and measuring tools mentioned. What is the special objection to using the files?