Which drill? First among many questions is, do you want cordless or with cord?
Walk down the power-tool aisle of any hardware or home improvement store and you'll see there's a revolution going on in electric drills. You'll find corded and cordless examples, in many sizes and configurations. it's enough to confuse the handiest of handypersons. Electric drills and related twist tools outsell all other power tools, and these hard workers have always been favorites as Christmas gifts. But how can a shopper decide which to buy? How powerful does a drill need to be, and how is its power rated? Why does one drill that looks similar to another cost twice as much? How much should you spend? Do you need a drill, or a driver, or a rotary hammer? Should you buy a drill with a cord or one that runs on batteries? This basic primer tries to answer such questions and help you make an informed purchase. One reason there are so many twist tools to choose from is that many have been developed to do specialized jobs. Most of these tools you'll never (or rarely) need. But we've included even some fairly exotic drills in this roundup not because they belong in every homeowner's tool box, but because a time may come when you have a particular task to accomplish and want to rent the most appropriate tool for the purpose. (The examples shown were chosen to represent the variety of choices rather than to endorse any brands.) There are two more reasons for the proliferation of new entries in the drill market. For one, nickel-cadmium batteries have been improved enough to make cordless tools far more than just a novelty. For another, new self-tapping screws (ones that don't need pre-drilled holes) are changing the way things are being built: from subfloors to gypsum-board walls and ceilings, many parts of our houses are now being screwed together. Even the name of the tool has changed from drill to driver-drill. In the beginning If you've owned a corded power drill for a number of years, you likely own a trusty old 1/4-inch-chuck, single-speed, forward-only, 3- to 3.5amp model. It's fine for drilling small holes but impossible to use for driving screws. Today, this little dinosaur has all but disappeared. The basic drill in the current market, whether corded or cordless, has a 3/8-inch chuck, a variable-speed trigger, and a reverse switch (VSR). If you were on the cutting-or drilling-edge a few years ago, you may have a small, 2.4-volt, single-speed screwdriver that you have to charge for 5 to 12 hours. Though this kind of tool is still available (but now with a 3-hour charge), drills with two to three times the power are more common. Most of them recharge in an hour, and they have features that hadn't even been thought of when the first cordless models hit the shelves. Cordless drills: the pros and cons The obvious advantage of a cordless tool is that you don't have to run cords to where you're working. The disadvantage is that you can only do so much work before the tool needs recharging. Nickel-cadmium batteries work well in today's rechargeable tools because they retain most of their power until the bitter end, then die a sudden death; other kinds of batteries slowly get weaker and weaker. Older rechargeable ni-cad batteries suffered from a couple of drawbacks: they took a long time to recharge, and you had to run them down all the way before recharging or they wouldn't take a full charge. Today's quicker-recharging batteries are designed to be left in a charger for a timed recharge whenever they're not in use. Ni-cad cells are rated at 1.2 volts each. The smallest driver-drills contain a battery pack of two cells, so they're rated at 2.4 volts. The next size is 3.6 volts (3 cells), then 4.8 (4 cells), 6 volts (5 cells), 7.2 volts (6 cells), 9.6 volts (8 cells), and finally 12 volts (10 cells). Recharge time is another consideration when you buy a cordless tool. Some require 3 hours, many only an hour. The fastest can recharge in 15 minutes. Many of the smaller drills plug right into a charger; with more powerful ones (7.2 to 12 volts), a battery pack can be removed from the tool and put in the charger-so you can buy an extra battery pack (about $35) and continue working while the first one is recharging. For remote work, you can buy a 1- to 3-hour charger that plugs into a car's cigarette lighter. Varying terms of comparison can make choosing a cordless drill difficult. For instance, one manufacturer may claim its 9.6-volt drill will, with an hour's charge, screw 400 3/4-inch #9 screws into medium-hard wood; a competitor's drill of equal voltage boasts of 104 inch-pounds of torque; a third manufacturer assures you its comparable drill can make six 1-inch holes in a 1/16-inch-thick steel plate. If these drills all have the same 9.6-volt power, how can they have different driving ability? The answer-aside from some modest differences in friction-reducing bearings-is in gearing. Check to see what the drill's maximum speed is. In comparing same-power drills, the slower a drill turns, the more torque-or twisting muscle it's likely to offer. If you think you'll mainly need to drill small holes, choose higher speed; if you're planning to drive screws, go slower, or choose a two-speed. For small home-maintenance projects, a 2.4- or 3.6-volt drill can be very useful. But in order to provide sufficient power, these tools are geared very low; they turn as slowly as 120 rpm (though some two-speed models can go to 350 rpm). You can tackle more tasks with the intermediate 6- and 7.2-volt tools; they not only offer more power, but they turn up to 600 rpm. And many come with variable-speed triggers- a handy control feature. For the serious handyperson or remodeler, choose a 9.6- or 12-volt tool. These offer power and speed up to 1,500 rpm. Some also have features like 15-minute charging and adjustable clutches (so they disengage when a certain amount of resistance is met, as when a screw is seated). All but the smallest drivers have 1/8-inch chucks. Models with cords There are many more kinds of drills with cords than without. Their chucks can take 1/4-inch, 3/8-inch, 1/2-inch, or even 3/4 or 7/8 inch drill shanks. Their motor power is rated in amps: 1/4-inch drills usually have 3 to 3.5 amps, 3/8-inch drills range from 3.5 to 5 amps, and 1/2-inch drills are powered by motors drawing from 3.2 to 7.5 amps. (The big ones can actually break your arm!) Again, gearing alters both speed and torque. The same 3.5-amp, variable-speed motor can be geared to turn from 0 to 850 rpm or 0 to 2,500 rpm. As shown on page 80, the basic tool has many variations. Some are geared for drilling holes, others for driving screws. Hammer and rotary hammer drills pound the bit as it turns. impact wrenches are clutched to give bursts of tightening power. All these tools can be used as drills, as well as for other purposes, such as drilling into concrete to add seismic tie-downs for your foundation or tightening lag screws for a deck. A few more things to consider With cordless drills. Notice where the chuck key stores (without a cord, there's no place for it to hang) and how the batteries snap in and out. What about extras-a hand strap or belt clip? Does the drill have an electric brake, or does the motor slowly stop spinning when you release the trigger? With corded drills. Check the length and quality of the cord. With all drills. Examine the chuck. Machined chucks adjust more smoothly and last longer than those with cast-metal cups. Try out one of the new keyless chucks. Don't be afraid if the body is plastic; most plastics are as strong as or stronger than metal. Does the drill have sleeve bearings, or longer-lasting ball or roller bearings? Does the tool feel balanced-big enough for what you want it to do, but not so big it's cumbersome? Are the reverse switch and clutch switch located in handy positions? Don't hesitate to shop around. No one store carries all kinds: like car dealers, tool stores sell only certain brands, and because the market is competitive, prices vary greatly. The prices we've shown are roughly list; if you shop around you can find some of these tools at close to half that cost, but make sure you're comparing apples and apples. Finally, talk to friends with driver-drilis and ask if you can test-drive a few screws.
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|Date:||Dec 1, 1990|
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