=39. The scriber or scratch awl= (_C_, Fig. 20) is used in marking holes, sawing, chipping, or in laying out distances, which can afterward be marked with a center punch if required. It should be made of a good quality of steel, and the point should be well hardened so that it will cut through the surface scale of the metal. A suitable-sized steel for making a scriber is 3/16 inch round and the length over all about 6 inches.
=40. The square= (_D_, Fig. 20) is another indispensable tool when accurate work is to be produced. Convenient sizes for manual training work are the 8 × 12-inch, with a 16 × 24-inch for general use.
=41. The bevel= (_E_, Fig. 20) should be used when bending and laying out angles of various degrees. When metal is to be bent to a given angle, the pupil should set and use the bevel.
=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.
[Illustration: 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.