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Tool Test: Cordless Impact Drivers


Cordless impact drivers offer big power in small packages.

By Mark Clement

Publication Date: May/June 2004; Photos: David Sharpe

My college rugby coach used to encourage the small guys on our squad (me) by saying, "It doesn't matter how much dog is in the fight. It only matters how much fight is in the dog."

While Coach Ortale's phrase fired me up in my rugby days, it's also an apt description of cordless impact drivers. They're small, yes, but also powerful and fast. And, compared to cordless drills, they're easier to use and can do more things. While about half the size and three times the torque as cordless drills, impact drivers are at home bulldogging foundation bolts or setting cabinets. And, since getting my hands on impact drivers about two years ago, I find my cordless drill spends more time in its box than ever.

Test Criteria

The nine drivers in this test range from 12 to 18 volts. I tested four 12-volt models: the Hitachi WH12DM2, Makita 6916DWDE, and Panasonic's EY6506NQKW and EY7201GQW; four 14.4-volt tools: DeWalt DW054K-2, Hitachi WH14DMB, Makita 6932FDWDE, and Milwaukee 9081-22; and the industry's only 18-volt unit, the DeWalt DW056K-2. I drilled and drove in heavy- and light-duty applications on site, turning 1/2-by-6-inch lag screws and cinching carriage bolts for a sundeck and crunching down foundation bolts on a stem wall. I also hung interior doors, installed vinyl replacement windows, and screwed down a 1/4-inch plywood subfloor for vinyl sheet. I drilled small pilot holes for door hardware and predrilled deck parts. Then, I went into the shop for head-to-head drilling and screwdriving, timing how long each unit took to drive a 1/2-by-6-inch lag, counting how many 4-inch Timberlock screws each tool sank, and recording drilling speed through double 2-by.

General Use

Heavy-Duty Work. In my past life as a home improvement contractor, I built several sundecks a year and relied way too much on wrenches and ratchets to tighten bolts and lock together handrails and posts. For the decks I've built since then, I've come to rely on impact drivers—mini powerhouses that make the work faster and easier. Each unit in the test group proved invaluable for getting carriage bolts snug, driving lags, and sinking 3-inch deck screws by the fistful. They fit into joist bays and can drive a screw straight through a deck board if the driver bit is long enough. I also used them to predrill deck parts with sharp 3/8- and 1/2-inch spade bits, which proved easy work for them.

The larger-bodied, 14.4- and 18-volt tools felt more solid and vibrated less while driving lags than some of the 12-volt tools. The Hitachi 12-volt WH12DM2 showed big power here and drove lags like a larger tool. The Panasonic EY7201GQW worked nicely here, too. The Makita 6916DWDE and Panasonic EY6506NQKW struggled a bit with the lags (the Makita was slow and the Panasonic wobbled around the screw head noticeably).

The whole group also cranked down foundation bolts about 100 times faster than any ratchet or wrench I've ever used. Plus, there's no reaction torque when the nut seats, as there is with a drill. This is nice for keeping your shoulder joint in its socket. The only limitation was on bolts that stuck higher above the mud sill than the depth of the socket. Still, across the range of heavy-duty applications, all the tools in the test group performed well.

Light-Duty Work

Each driver also performed nicely in lighter applications like door hanging and installing windows and cabinets. While these tools have a truckload of power and speed, their variable-speed triggers are sensitive enough to snug pan-head screws to vinyl window jambs or cabinet backs. It's even easy enough to set drywall screws properly for small repairs. For very gentle work, like installing cabinet hinges or some woodworking tasks, however, a lower-rpm, lower-torque cordless drill is a safer bet.

On these lighter-duty projects, the 12-volt tools excelled. While the 14.4s and 18-volt worked just fine, the 12-volt models are so light, compact, and easy to hold that I just want to pick them up, particularly the Hitachi WH12DM2 and Panasonic EY6506NQKW. And by comparison, these impact drivers made my otherwise perfect 18-volt cordless drill feel larger and more awkward than it had before I started this test.

Shop Tests

In the shop, I staged power and run-time tests so I could evaluate the tools all in one place, at the same time, and in the same material. I also took a closer, side-by-side look at the balance, fit and finish, bit exchange, battery exchange, toolbox, and extra features on each tool.

Power & Run Time

Drilling. To get a better sense of head-to-head performance, I simulated a deck-ledger assembly with treated 2-by, 3/4-inch plywood, and the driest, hardest piece of Douglas fir 2-by I could find. Since each tool sailed through deck parts on site with sharp 3/8- and 1/2-inch spade bits, I used a 1-inch spade bit. While all but the 12-volt Makita and Panasonic EY6506NQKW made it through the stack, it wasn't pretty for any of the tools: Each shook excessively and bogged down. For any hole over 3/4-inch, it's best to use a cordless drill/driver or plug-in. Smaller holes were a breeze.

Driving Lags. If you build a deck a day in subdivisions full of production houses, you may want to dedicate an electric impact wrench to your crew. These cordless drivers may not be up to day-in, day-out production-driving work like that. But if you're looking for a tool that can step up to deck work, while also shining on all kinds of other projects, then these small drivers are terrific time-savers—and you may find you're leaving the bulky corded impact driver in your shop.

To rate performance under major strain, I sank two 1/2-by-6-inch screws with each tool into the simulated ledger assembly through predrilled 3/8-inch holes, timed how long the tools took to seat each screw, and recorded the average.

The king of the hill was Hitachi's 14.4-volt model at an average of 14.5 seconds. It felt powerful and drove the lag down hard. It also had the single best time: 13 seconds. Next came the 14.4-volt Milwaukee at 16 seconds with consistently powerful drives; the 18-volt DeWalt at 17.5 seconds; and the 12-volt Hitachi and 14.4-volt DeWalt, both at 18 seconds. These last two tools felt strong up until the very end when they strained, but the work they accomplished was reasonable. The 12-volt Panasonic EY7201GQW was next, sinking the screws in 20 seconds, but was definitely working hard to seat them. Then, the 14.4-volt Makita and 12-volt Panasonic EY6506NQKW both sank the screws in 21 seconds. Makita's 12-volt tool took 24 seconds.

Screwdriving. Since my arm would fall off long before I could wear all these tools down driving 3-inch deck screws, I chose 4-inch-long Timberlock screws to see how long the batteries would last when pushed to the screw-turning max, counting how many each tool twisted in before the battery showed a noticeable slowdown.

Even driving these thicker, heavier screws, my arm almost did fall off trying to run the Milwaukee 14.4-volt tool and 18-volt DeWalt dry. The 14.4-volt Milwaukee outran the group, sending 46 Timberlocks crunching into the stock. Close behind, DeWalt's 18-volt tool knocked down 42. Next came the 12-volt Panasonic EY7201GQW with 37, Hitachi's 14.4-volt with 36, and the Panasonic EY6506NQKW with 32. The Makita 12-volt unit had 30 solid sets.

Makita's 14.4-volt tool was next with 28 Timberlocks, followed by the 12-volt Hitachi with 24 screws nicely set. The 14.4-volt DeWalt solidly sank 21.

Fit & Finish

Balance and Feel. If an 18-volt cordless drill is a .44 magnum, then an impact driver is James Bond's Walter PPK—snug, small, and low-profile, but equally effective. The first thing I noticed when I picked up the 12-volt Hitachi and Panasonic EY6506NQKW is that they nestled well in my hand. The handles are easy to hold and the tools are easy to manipulate, whether driving boxes of deck screws or craning my arm to start a screw in the top hinge of a door. The rubber handles and bonnets are excellent spots for my opposite hand to guide the tools. The triggers are also nice on both units, with no pinch points. Next, I found both DeWalt tools very com fortable. I like the rounded rubber triggers and handles as well as the rubber bonnets covering the back of the tools.

The rest of the tools are all nicely balanced and comfortable enough for all-day use. However, while I found the Panasonic EY7201GQW comfortable, my hands are small and I think its handle would be snug for workers with larger hands. In contrast, both Makitas' handles are thick (to accommodate their larger battery stem) and feel like they'd be more at home on a larger tool—or more comfortable for workers with larger hands than mine. The 14.4-volt Hitachi and Milwaukee also fit my hand fine, but since they're the largest tools in the bunch, these models feel more like drill/drivers than impact drivers.

Bit Exchange. The whole world should be on the 1/4-inch hex drive system. With all due respect to keyless chucks, they can't come close to a hex drive's plush operation—bits pop in and out without a hiccup and once they're locked in, they don't slip or fall out. Ever. Plus, a hex drive is about one-tenth the size of a keyless chuck with fewer parts to break or wear out. All the drives worked perfectly. Forced to pick, though, Makita's is best: Its knurled collar is totally non-slip and easy to grab, even with gloves on. I really liked it for hanging doors, where I'd switch between drill and driver bits frequently.

Battery Exchange. Even with my small hands, the battery release pinch tabs on both of the DeWalt models and both Makitas are easy to reach, and they release the batteries effortlessly. Next, I like Milwaukee's slide-on battery. It takes a few tries to get used to its different design, but it works great. Also, this battery is reversible, which is a nice feature. Both Hitachi units have fine releases. The Panasonics' are a little awkward because I can't reach them from the bottom of the tool; instead, I have to get at them from the front, which isn't my natural instinct.

Toolbox. A good toolbox is important to me for storing and transporting tools and bits. Milwaukee's is best, with a smart layout and a great compartment for extra bits. The Panasonic boxes are also tough. The rest of the boxes are serviceable, but don't appear as tough.

Extra Features

Belt Hooks. Both Hitachi units and the Panasonic EY7201GQW have adjustable belt hooks. I love having a hook; they're excellent for carrying tools when your hands are full or hooking the tool onto your belt while on a ladder. However, for these tools, the concept was a little better than the execution. For instance, the hooks on all three tools require two hands to adjust so they can grab a belt, and they're hard to adjust smoothly. Once turned so they'll hang on a tool pouch, the hooks got in the way if I switched to using the tool left-handed. I found this bothersome inside cabinets and window frames, where I switch hands to drive screws in different corners. If the hooks could be integrated with the tool body, it might avoid some of these conflicts. But, after all that complaining, I'd rather have the hook than not.

Work Lights. These same three tools also have LED lights. The Hitachis' lights are part of the belt hook, have an on/off switch, and work fine. Pulling the trigger illuminates the Panasonic EY7201GQW's light. I suppose I can figure a few instances where a little light would be nice, but frankly I've never found a need for them—and I did a lot of this test at night.

Speed Settings. Only the Panasonic EY7201GQW has slow- and high-speed settings, which I love. This makes what is otherwise a very high-rpm tool much, much easier to control, especially on gentler work like hanging doors and drilling small pilot holes. I wish all the drivers had this feature.

Noise. Every tool in the group generates extra noise. For what they lack in size, the Napoleonic drivers make up for in loudness. The good news is that in many light-duty applications, they drive without impacting for most if not all of the screw's length, rendering them quiet much of the time.

One of the many positive results of the noisy impact feature, however, is that while you need to push hard and make a solid connection between the driver bit and screw to start the screw, once you're turning threads you don't have to lean on the tool to make it go, like with a drill/driver. Good, steady pressure is all you need, which is another energy saver.


Since the test group is all over the voltage map, picking a single winner requires some qualification, as some of these tools really shine in certain applications. For bulldog power, I like Hitachi's 14.4-volt WH14DMB. It's basic and a little big, but has a ton of muscle. Milwaukee's 14.4-volt 9081-22 is a close second here. For trim and cabinets, the super-compact 12-volt Panasonic EY6506NQKW is superlative.

But for general purpose work, Hitachi's 12-volt WH12DM2 is the most versatile and my overall favorite. It's compact, light, and great on trim sites, but also has awesome power for digging into lags and heavy-duty work, proving itself the fightin'-est dog on site.

Next, both DeWalt tools are comfortable and powerful. Panasonic's EY7201GQW is an advanced, versatile tool, while both Makita models provide dependable service.

--Mark Clement is executive editor of Tools of the Trade.


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