Evaluating Power Drills

Drills aren't just for handymen; they are the most popular power tool in the United States. You can use drills for everything from hanging pictures to changing a car's tires. What you can do with a drill depends on the power, size and features of the drill you select. Before you head off to the hardware store, do some research and evaluate your needs.

Corded or Cordless?
Improved Lithium-Ion batteries have improved the quality of cordless drills, but corded models remain the best solution for some jobs. In deciding between the two, you need to know if the power and reliability of a corded drill is more important than the portability of a cordless drill. Choose a corded drill if you'll be drilling hardwoods or pressure-treated wood, concrete or masonry. Corded drills are the only way to go if you'll be drilling eight hours a day.

Cordless drills are an excellent choice for work around the house and some light carpentry applications, such as finish work on eaves or rooflines, where cords can be a hassle. Look for cordless drills with Lithium-Ion batteries instead of Nickel Cadmium (NiCd) batteries that can quickly develop battery memory, a condition that reduces available battery life.

A cordless drill should include two batteries and a charger, so that you will always have a charged battery available. Look for smart chargers that give you a visual indication of the charging status and that turn themselves off when charging is complete.

Drill Power
The power of a cordless drill is determined primarily by its voltage; the power of a corded drill by its amps. More volts or amps translate into more available drill power. It's best to avoid cordless drills with less than 12 volts of power, as they will struggle with drilling all but the softest materials. An 18-volt drill is more than enough for most household and professional users. If the price tag is too high, choose a 14.4-volt drill, which can handle indoor projects with ease.

For corded drills, 3.5 amps are enough for most types of wood. Thick decking, concrete or masonry work will be easier to handle with a drill that uses 5 amps or more.

In addition to volts or amps, you should compare the torque of the drills you are considering. Torque is a measurement of turning power. A drill with higher torque can cut or drive screws into denser, thicker material.
Some drills offer torque clutches that will stop the drill if it encounters too much resistance. This is a good feature if you'll be using your drill to drive screws, as it prevents you from stripping the heads. Look for drills that let you adjust the torque clutch to prevent the drill from seizing when you're drilling thick or dense material.

Drill speed is measured in RPMs. Budget-priced drills have a single speed setting, but you'll want a drill to feature adjustable speeds to handle a greater variety of materials. If you use your drill to drive screws, you will need to use a much lower speed than you would for drilling. Adjustable speeds benefit cordless drills by allowing you to tailor the speed to the job at hand, saving battery life.

Drill Size and Chucks
A drill's size is a measurement of the drill bits it can use. Most drills use either ¼ inch, 3/8 inch or ½ inch drill bits. The best and most flexible choice is a 3/8 inch drill, as you'll find the greatest selection of drill bits for these models. Smaller ¼ inch drills should be reserved for hobby work or fine furniture making, while the largest, ½ inch drills are suitable mainly for plumbing and masonry use.

The chuck holds the interchangeable drill bits. Chucks are available in keyed or keyless models. Keyless chucks work on friction and are a great choice for home and most professional use. It's usually quite easy to open and close these drill chucks, which makes changing bits a snap.

Choose a drill with a keyed chuck for heavy-duty jobs, such as decking and masonry. Keyed chucks hold bits more firmly than keyless chucks, reducing the chance of the drill bit slipping or becoming embedded in the material you're trying to drill. Look for chuck keys that are attached to the cord of a corded drill or that lock into the body of a cordless drill so that you'll have the key handy when you need it.

Handle Designs
The type of drill handle you choose is largely a question of personal preference and the type of work you'll do. It's important for a drill to feel natural in your hand, especially after you've been using it for a while.

T-handles, mounted near the center of the drill, are the most popular choice. This design balances the weight of the drill and offers good control on vertical surfaces, such as walls. Pistol-grip handles are mounted on the back of the drill, letting you push the full weight of the drill into the work. Pistol-grip handles are the best choice for horizontal work, such as floors and decking, or heavier drilling jobs where greater stability is needed.

In normal use, these drill handles position the bit straight ahead of your hand. Right-angle drills have the bit pointing downward at a 90-degree angle from your hand. They're good for tight spaces and some specialized bolt or screw driving applications, but not for general use.

Compare the shipping weights of drills to find a weight that's easy for you to hold. Corded drills weigh far less than cordless models, because you don't need to carry the extra battery weight.

Drill extras
Make sure a drill is reversible if you'll be driving screws or bolts. Hammer action, which drives the drill bit forward and backward on a piston, is a good feature for a drill that you'll use on masonry.

If you're working in corners or on ceilings, look for a drill with an adjustable angle that makes these jobs easier. For larger drills, choose one with a rotating or screw-in auxiliary handle that allows two-handed stability on demanding jobs.