POWER TOOLS

POWER TOOLS LEARNING OBJECTIVES: Identify the different types of power tools. Describe the uses of different types of power tools. List the safety precautions that apply to power tools. List the safety precautions that apply to extension cords. Power tools have become so commonplace in the Navy that all ratings now use them in the performance of maintenance at one time or another. The following paragraphs are devoted to the identification, general-operating practices, and care of these tools. DRILLS The portable electric drill (fig. 1-59) is probably the most frequently used power tool in the Navy. Although it is especially designed for drilling holes, by adding various accessories you can adapt it for different jobs. Sanding, sawing, buffing, polishing, screw driving, wire brushing, and paint mixing are examples of possible uses. Portable electric drills commonly used in the Navy have capacities for drilling holes in steel from 1/16 inch up to 1 inch in diameter. The sizes of portable electric drills are classified by the maximum size straight shank drill it will hold. That is, a 1/4-inch electric drill will hold a straight shank drill bit up to and including 1/4 inch in diameter. The revolutions per minute (rpm) and power the drill will deliver are most important when choosing a drill for a job. You will find that the speed of the drill motor decreases with an increase in size, primarily because the larger units are designed to turn larger cutting tools or to drill in heavy materials, and both of these factors require slower speed. If you are going to do heavy work, such as drilling in masonry or steel, then you would probably need to use a drill with a 3/8- or 1/2-inch capacity. If most of your drilling will be forming holes in wood or small holes in sheet metal, then a 1/4-inch drill will probably be adequate. The chuck is the clamping device into which the drill bit is inserted. Nearly all electric drills are equipped with a three-jaw chuck. Some drills have a hand-type chuck that you tighten or loosen by hand, but most of the drills used in the Navy have gear-type, three-jaw chucks, which are tightened and loosened by a chuck key, shown in figure 1-60. Do not apply further pressure with pliers or wrenches after you hand tighten the chuck with the chuck key. Always remove the key IMMEDIATELY after you use it. Otherwise the key will fly loose when the drill motor is started and may cause serious injury to you or one of your shipmates. The chuck key is generally taped on the cord of the drill; but if it is not, make sure you put it in a safe place where it will not get lost. All portable electric drills used in the Navy have controls similar to the ones shown on the 1/4-inch drill in figure 1-59. This drill has a momentary contact trigger switch located in the handle. The switch is squeezed to start the electric drill and released to stop it. The trigger latch is a button in the bottom of the drill handle. It is pushed in while the switch trigger is held down to lock the trigger switch in the ON position. The trigger latch is released by squeezing and then releasing the switch trigger. 1-37 Figure 1-59.—1/4-inch portable electric drill. Figure 1-60.—Three-jaw chuck and chuck key.