FILES

The type of chisel most commonly used is the flat cold chisel, which serves to cut rivets, split nuts, chip castings, and thin metal sheets. The cape chisel is used for special jobs like cutting keyways, narrow grooves, and square corners. Round-nose chisels make circular grooves and chip inside corners with a fillet. Finally, the diamond-point is used for cutting V-grooves and sharp comers. As with other tools there is a correct technique for using a chisel. Select a chisel that is large enough for the job. Be sure to use a hammer that matches the chisel; that is, the larger the chisel, the heavier the hammer. A heavy chisel will absorb the blows of a light hammer and will do virtually no cutting. As a general rule, hold the chisel in the left hand with the thumb and first finger about 1-inch from the top. It should be held steadily but not tightly. The finger muscles should be relaxed, so if the hammer strikes the hand it will permit the hand to slide down the tool and lessen the effect of the blow. Keep the eyes on the cutting edge of the chisel, not on the head, and swing the hammer in the same plane as the body of the chisel. If you have a lot of chiseling to do, slide a piece of rubber hose over the chisel. This will lessen the shock to your hand. When using a chisel for chipping, always wear goggles to protect your eyes. If other personnel are working close by, ensure they are protected from flying chips by erecting a screen or shield to contain the chips. Remember that the time to take these precautions is before you start the job. FILES A toolkit for nearly every rating in the Navy is not complete unless it contains an assortment of files. There are several different types of files in common use, and each type may range in length from 3 to 18 inches. Grades Files are graded according to the degree of fineness and according to whether they have single or double-cut teeth. The difference is apparent when you compare the files in figure 2-8, view A. Single-cut files have rows of teeth cut parallel to each other. These teeth are set at an angle of about 65 degrees with the center line. You will use single-cut files for sharpening tools, finish filing, and drawfiling. They also are the best tools for smoothing the edges of sheet metal. Files with crisscrossed rows of teeth are double- cut files. The double cut forms teeth that are diamond-shaped and fast cutting. You will use double-cut files for quick removal of metal and for rough work. Figure 2-8.—File descriptions. 2-6