Work faster and better with a cordless impact driver. We show the basic techniques and pick our favorite driver models, after testing many available options.
By the DIY experts of The Family Handyman Magazine
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Cordless impact driver 101—the basics
A few years ago, cordless impact drivers were a specialty tool, rare on job sites and scarce on store shelves. Today, you’ll see several models at any tool retailer and hear their machine-gun chatter wherever there’s construction. When a tool gains popularity that fast, you have to wonder what’s going on. And, more important, what you’re missing.
To sort out the pros and cons of impact drivers, we put them in the hands of our staff editors and field editors, who are pros on the job and DIY guys at home. Here’s what we learned about cordless impact drivers:
Tip 1: It’s all about torque
Drive long screws
You can drive long screws because impact drivers generate a lot of torque.
Impact drivers have one overwhelming advantage over standard drills and drivers: enormous torque. Basically, that means you can drive a big screw (or bore a big hole) with a small driver. In this photo, we sank 3/8 x 10-in. self-drilling lag screws into cedar lumber. No pilot holes, no cheating.
Tip 2: Not just for driving screws
Bore big holes
Impact drivers can easily handle big bits for boring large holes.
Impact drivers make great drills. With small bits (up to 1/4 in. or so), they act like a drill—but at nearly twice the rpm of most cordless drills. With bigger bits, they kick into high-torque impact mode so you can bore a big hole with a small driver.
Tip 3: One-handed driving
The drill bit stays engaged, allowing for easier one-handed driving.
With a standard driver, you have to get your weight behind the screw and push hard. Otherwise, the bit will “cam out” and chew up the screw head. Not so with an impact driver. The hammer mechanism that produces torque also creates some forward pressure. That means you don’t have to push so hard to avoid cam-out. Great for one-handed, stretch-and-drive situations.
Tip 4: The only driver you’ll ever need?
Maybe. An impact driver will handle just about any job, and some of our testers have already retired their old drivers. But when high torque isn’t needed, most of us like to avoid the noise and reach for standard cordless drills or drivers instead.
Tip 5: Loud, really loud
Protect your hearing. Impact drivers are loud.
An impact driver can bring a heavy-metal drummer to tears. Wear muffs or earplugs—or get fitted for a hearing aid. Your call.
Tip 6: It’s not a hammer drill
An impact driver works kind of like a hammer drill and sounds a lot like one. But it’s no substitute for a hammer drill. An impact driver’s innards are engineered to generate torque, not powerful forward blows.
Tip 7: Use hex shafts only
Hex shaft drill bit
The driver chuck only accepts hex shaft bits.
The chuck on an impact driver makes for quick changes; just slide the collar forward and slip in the bit. But you’ll have to buy hex-shaft drill bits. Regular bits won’t work.
Tip 8: Small and smaller
Generally, there’s a big torque difference between 12- and 18-volt models. But some of the 18-volt sluggers are amazingly compact—not much bigger than their 12-volt cousins. Big torque in a compact tool—that’s why most of our testers favored the 18-volt versions.
Driver Size Comparison
The 18-volt driver is only slight larger than the 12-volt driver. Both are compact.
Tip 9: Easy to handle
Easy on the arm
Despite the torque, an impact driver is easy to handle.
You might think that extreme torque puts extreme strain on your arm. Nope. For reasons Isaac Newton could explain, an impact driver actually generates less wrist twist than a standard driver. Don’t be fooled by the macho-man feeling you get when you effortlessly sink a big screw. A little princess can do the same thing.
Tip 10: Consider a combo kit
You save when you buy a combo kit.
For a few bucks more than an impact driver alone, you can add a driver, a drill or a hammer drill to your tool collection. This driver/impact driver twosome cost us just $25 more than either tool sold separately. We couldn’t resist.
Tip 11: Prepare for impact
Most of the items in an accessory kit will come in handy.
Pick up a set of hex-shaft accessories for about $25 (drill bits, driver bits, socket adapters). You’ll want most of that stuff sooner or later, and buying a kit will save you a few bucks. Check the label and get a set that’s tough enough for impact-driver duty.
Tip 12: They all look alike outside, but . . .
The difference is how they transfer torque from the motor to the chuck. On a standard drill or driver, the motor and chuck are locked together through gears; as the workload increases, the motor strains. An impact driver behaves the same under light loads. But when resistance increases, a clutch-like mechanism disengages the motor from the chuck for a split second. The motor continues to turn and builds momentum. Then the clutch re-engages with a slam, transferring momentum to the chuck. All of this happens about 50 times per second, and the result is three or four times as much torque from a similar-size tool.
Impact Driver/Standard Driver Comparison
These two tools may look alike on the outside, but they operate differently.
Tip 13: Good for gearheads, too
They don’t have nearly the torque of big impact wrenches, but cordless impact drivers can be a time-saver when you tinker with engines. They’re perfect for small engines, where less torque is usually enough. For automotive work, consider an “angle” version, such as the Craftsman shown later. Hitachi, Makita, Ridgid and others also make angle impact drivers.
A lifetime battery warranty and two cool features: a clutch like the one on standard drivers, and adjustable impact mode.
It wasn’t easy, but after weeks of testing, retesting and arguing, we settled on six cordless impact driver favorites. The models shown here are widely available at home centers and hardware stores. If you’re willing to do some hunting, you’ll find several other models and manufacturers.
Tip: Watch for falling prices. Don’t be surprised if you find lower price tags than listed here. We watched prices during a six-week period and saw prices drop on one out of every four models shown here. The discounts (sometimes sales, sometimes permanent price cuts) were in the 10 to 20 percent range.
Cordless impact driver round-up and test results, continued
Of our 10 testers, eight gave this one the top rating. In our lag-screw races, it consistently matched or exceeded the others. In addition to raw power, it has all the features we loved: a tool-belt hook, a bright work light and a battery “fuel gauge.”
Bummer: No onboard bit storage.
Dissenting opinion: The DeWalt DCF826KL is better. It has almost as much torque, but it’s lighter, more compact and comfortable. — Gary Wentz, senior editor