Electric Drills

Half-Inch Drill. This is a more powerful model, typically with a three-quarter horsepower motor. Half-inch drills are available in pistol-grip configurations, but for some of the demanding drilling to which the half-inch drill is well-suited, a bulkier configuration that features a closed handle at the rear and an auxiliary grip on the side of the drill's body is probably the most generally useful. The added handholds allow you not only to steady the tool as it drills, but to apply additional pressure while drilling. Working two-handed will also help insure that if the drill becomes caught in the work the drill won't twist itself out of your grip.

Most half-inch drills are designed to turn at fewer revolutions per minute, but have more power. That makes them indispensable for drilling large diameter holes through dimension lumber and timber (for utility lines), in mixing plaster or joint compound, or for other heavy-duty tasks.

Cordless Drill. These tools are convenient: There's no cord trailing you up the ladder or circling your feet, threatening to trip you up. They can be used almost anywhere, even miles from the nearest electrical outlet. For some tasks, they're just about essential.

With the good news, though, there's a bit of bad news, too. Cordless drills are heavier than corded drills, because the power source is a rechargeable battery that adds weight. Most designs are well balanced, but if you're accustomed to using a traditional drill, the added weight will feel strange in your hand, at least at first.

Cordless drills also have less power available to them, so for some drilling and driving jobs the built-in clutch on most models will, from time to time, alert you to the limited power of the cordless drill (the bit will stop turning and you'll hear the clutch clicking). Newer models have improved torque, but raw power just isn't the forte of the cordless drill.

Remember that the cordless drill works only as long as its battery is charged. The charge will last a surprisingly long time (many days, given only occasional use), and professionals keep a spare battery on hand. Most models recharge in approximately an hour.

Cordless drills are usually reversible; some have the same variable speed control as corded models, which functions by depressing the trigger gently for low speeds, harder for higher ones. Some models have just one or two speeds (roughly five hundred revolutions per minutes and twelve hundred revolutions per minute are typical) and a speed-control switch.

Other Options. For making holes in concrete, a variation of the power drill called a rotary hammer is available. It delivers its power in a hammering motion as it drills, using specially designed percussion bits. Some models hammer out tens of thousands of strokes per minute. Another purpose-made drill is an impact wrench, which is used for tightening (or loosening) nuts and bolts. The impact wrench is a standard in auto shops.