Electric Power Drill

Electric power drill is a great carpentry tool that every carpenter should have. One of the most versatile power tools you can buy actually a first choice on any list of practical power tool equipment—is the portable electric drill. The name "drill- doesn't tell the story, even though the tool is fantastic for drilling small or large holes accurately and with minimum effort. A more realistic picture because of modern innovations and the myriad accessories that have become available for it, is of a lightweight, multipurpose shop you can hold in your hands. Alone, like many other electric tools, it can't do anything but spin its chuck, but add a suitable accessory and the unit serves efficiently as a drum or disc sander, grinder, polisher, screw ­driver, flex-shaft machine, doweling jig, and more. It can also be used as a power source to drive specially designed units like a handsaw, belt sander, even a small lathe. Place it in a stand and it will serve as a stationary drill press. The combination of portable drill and accessory isn't meant to be a substitute for the tool it imitates, however, the ideas do work.

The mechanism of a portable drill is fairly simple. A motor in the electric power drill drives a chuck which grips a cutting tool. In between motor and chuck is a system of gears that provides the correct torque and speed for what the drill is designed for. While this is the basic concept there are other factors that are part of the picture; variable speed controls, double insulation, reversing switch, electronic features, and power.


Electric power drill sizes you might be interested in are, 1/4", 3/8", and 1/2". The size indicates the maximum tool-shank diame­ter that can be gripped by the chuck not necessarily its drilling capacity. There are many cutting tools, like spade bits, that range up to 1 1/2" and have 1/4" shanks. Hole saws and the like can be used to form holes well over what you can accomplish with a drill bit but many of them have 1/4" shanks and can be gripped in a small capacity drill. But it's not all roses. Complete freedom to use any cutting tool in any drill is another matter. The unit may not have the power or the efficient combination of power and speed to do the job.

The capacity of a electric power drill can usually be judged by the manufacturer's specifications. The 1/4" unit shown in, with a speed range of 0-2000 rpm. is rated at 2.7 amps and can form 1/2" holes in hardwood and 1/4" holes in steel. As the size of the drill increases so does its power however, its top speed usually decreases. The 3/4" drill shown in Figure 5-3 is rated at 3.2 amps. has a speed range of 0- 1200 rpm, and can drill 3/4" holes in hardwood and 3/8" holes in steel. Move up to a 1/2" tool like the one in and you can drill 1/2" holes in steel and 1" holes in hardwood. This particular drill has an amp rating of 4.5 and a speed range of 0-850. Note that the size of the drill usually tells the maximum size hole it should be used for in steel, and that size doubles in hardwood.

The fact that speed decreases as power goes up tells something about good practice with electric drills. Jobs like drilling 2" holes in steel call for good power and low rpm. Of course, there is always some overlap in functions even among tools that are different sizes. You can occasion­ally use a "small" drill beyond its capacity for holes in steel by working in steps; start with a small bit and gradually increase bit-size which, by the way, is generally good practice with any electric power drill. On the other hand there's no reason why you can't use a "large" drill to form very small holes. Over-taxing the tool is what to avoid. If the tool gets too warm, or stalls, or its speed decreases drastically, you are asking too much.

Not too long ago when you selected a drill for its power or chuck capacity you got a single, compatible speed with it. The combination of size-capacity-speed made the unit ideal for a particular category of work. Such tools are still available and they may even be a good choice if you require no-fuss performance for a particular application. However the tool would be a compromise for general-purpose use. For example, it might be too fast for drilling in steel, too slow for small holes in wood.


The trigger-controlled variable speed feature that is available on drills of all sizes does away with the limitation of one speed and makes any drill a more versatile tool. Many times it's good practice to start work at a slow speed and gradually increase rpm until the cutter is working without strain. This variable speed feature also makes any electric power drill an electric screwdriver, since choosing the right speed for such work is critical. Add a reversing feature, also generally avail­able, and you can remove screws as well as drive them.


Electronic technology is making it easier to use a par­ticular speed. The 3/8" drill in has electronic analog feedback which maintains the desired speed under loaded conditions.

The ability to work anywhere, even without electricity, and being able to function without the fuss of a dangling cord has made the new cordless drills quite popular. For more basic carpentry tips visit this website.