ELECTRIC IMPACT WRENCH

DISK SANDER Electric disk sanders (fig. 1-61) are especially useful on work where a large amount of material is to be removed quickly, such as in scaling surfaces in preparation for painting. This machine, however, must not be used where a mirror-smooth finish is required. The disk should be moved smoothly and lightly over the surface. Never allow the disk to stay in one place too long, because it will cut into the metal and leave a large depression. PORTABLE GRINDERS Portable grinders are power tools that are used for rough grinding and finishing of metallic surfaces. They are made in several sizes; however, the one used most in the Navy uses a grinding wheel with a maximum diameter of 6 inches. See figure 1-62. The abrasive wheels are easily replaceable so that different grain size and grades of abrasives can be used for the various types of surfaces to be ground and the different degrees of finish desired. A flexible shaft attachment is available for most portable grinders. This shaft is attached by removing the grinding wheel, then attaching the shaft to the grinding wheel drive spindle. The grinding wheel can then be attached to the end of the flexible shaft. This attachment is invaluable for grinding surfaces in hard-to-reach places. ELECTRIC IMPACT WRENCH The electric impact wrench (fig. 1-63) is a portable, hand-type reversible wrench. The one shown has a 1/2-inch-square impact-driving anvil, over which 1/2-inch-square drive sockets can be fitted. Wrenches also can be obtained that have impact driving anvils ranging from 3/8 inch to 1 inch. The driving anvils are not interchangeable, however, from one wrench to another. The electric wrench with its accompanying equipment is primarily intended for applying and removing nuts, bolts, and screws. It may also be used to drill and tap metal, wood, plastics, and so on, and to drive and remove socket-head, Phillips-head, or slotted-head wood, machine, or self-tapping screws. Before you use an electric impact wrench, depress the on-and-off trigger switch and allow the electric wrench to operate a few seconds, noting carefully the direction of rotation. Release the trigger switch to stop the wrench. Turn the reversing ring, located at the rear of the tool; it should move easily in one direction (which is determined by the current direction of rotation). Depress the on-and-off trigger again to start the electric wrench. The direction of rotation should now be reversed. Continue to operate for a few seconds in each direction to be sure that the wrench and its reversible features are functioning correctly. When you 1-38 Figure 1-61.—Portable electric sander. Figure 1-62.—Portable grinder. Figure 1-63.—Reversible electric impact wrench.