You’re likely to hear about impact drivers this holiday season as manufacturers hawk their ability to drive and loosen long or difficult bolts. But so far, no one is shouting about the fact that these new cordless tools are loud enough to damage your hearing.
The 5 impact drivers we tested averaged 104 decibels at ear level under heavy load far louder than standard cordless drills, as loud as chain saws, and well above the 85 dBA at which we recommend hearing protection. In fact, they’re among the noisiest power tools sold. Yet warnings about hearing protection are buried in their owner manuals.
You may still want an impact driver for its added power. Impact drivers typically handle the same drilling and screw driving tasks as conventional drills/drivers, but they emphasize driving by hammering as they spin.That gives them more than three times the twisting force, or torque, for more effective loosening and tightening. The downside of that added power is a jackhammer sound that can be as grating as it is loud when that torque is used.
Major brands are also beefing up conventional cordless drills as they fight for sales. Milwaukee’s new 28-volt V28 has the highest voltage we’ve tested and. The V28 effortlessly drove 312-inch lag screws into dense pine 4x4s in our tests. But extended work revealed that this 6.8 pound heavyweight had a glass jaw when it came to the heavy duty screw driving for which it’s intended.
Weeks of boring holes and driving lag screws revealed other shortcomings for cordless impact drivers and conventional cordless drills. Here are the details:
- Drivers can be slower, pricier: Most conventional cordless drills have a slower speed range for driving screws and a faster one for drilling. Impact drivers have just one range meant mainly for driving, which compromises drilling speed.
- Impact drivers add some convenience with a spring loaded chuck: The pullback chuck design makes removing and inserting drill bits and nut drivers easier to do than with the twist to tighten chuck on conventional cordless drills/drivers.
- The catch: You’ll need to buy special drill bits with 14-inch hexagonal shanks or spend $20 for an adapter if you want to use conventional, round-shank bits.
- Quick charging can cost you: Rapid battery recharging is especially welcome when working on decks and other large projects. Several cordless drills from Hitachi, Makita, and Ridgid can charge one or two batteries in just 30 minutes or less instead of the usual hour or more. But as the Ratings on page 48 detail, you’ll have to pay at least $200 to get both quick charging and respectable run time between battery recharges.
- More voltage can mean less: Milwaukee’s 28-volt drill isn’t the only high-powered cordless model that proved disappointing in our tests. Several 18-volt Black & Decker, Craftsman, and Skil drills couldn’t match some 14.4 and even some 12-volt cordless drills.
How To Choose
It doesn’t take long to damage your hearing. The National Institutes of Health recommends no more than 15 minutes of unprotected exposure to 100 dBA of noise. The agency also warns that regular exposure to more than a minute of noise at 110 dBA risks permanent hearing loss.
Impact drivers have sold briskly in Asia, where Panasonic says it has quieted them with oil cushioning technology. The company hopes to have a lower cost version for the U.S. in the next two to three years. Until quieter models arrive, we believe manufacturers should put impact driver noise warnings on the box and product, and include a set of earplugs.
If you’re considering an impact driver, see First Things First, opposite page, to determine whether the added twisting power is worth the added hassle and risk. Keep these points in mind as you shop:
- Decide how much drill you need: Paying $200 or more for any cordless drill typically buys top performance, quick charging, and relatively long run time between charges. But several drills we tested do nearly as well as the priciest models for around $100. What’s more, nearly any of these cordless drills are fine for hanging bookshelves, tightening doorknobs, and other light duty tasks.
- Check battery costs: New batteries typically cost $40 or more; expect between 500 and 1,300 charging cycles. Ryobi’s 18-volt cells cost around $20 and work with all of the company’s 18-volt tools. What’s more, you can buy some Ryobi and Craftsman tools without a battery so that several can share the same one.
- Think carefully about kits: Cordless kits can save money by bundling a drill, reciprocating saw, circular saw, and other tools with two batteries and a charger. But some of these kits may be less than a bargain. While cordless reciprocating saws can match corded saws, cordless circular saws have performed anemically.
- Keep it safe: Wear safety glasses or workshop goggles and hearing protection when using any power tools, especially impact drivers.
Best for drilling holes, driving and removing screws, and other around the house projects. None required hearing protection in our tests.
But some models aren’t powerful enough to effectively turn stuck screws and large bolts in dense wood. Models with the most twisting power also tend to twist awkwardly in your hands.
Best for driving and removing long screws and bolts. Most can handle car wheel nuts and other tougher tasks, and they don’t twist in your hands.
But these tools are loud enough to cause hearing damage without protection. They drill more slowly than comparable drills/drivers and require special hex shank bits or a $20 adapter.
These features add ease and performance:
- 30 minute charger: Found on some drills and impact drivers, these charge the battery in as little as 20 or 30 minutes rather than an hour or more. They also monitor battery temperature to prevent overheating or damage by not recharging one that’s too hot. Models judged good or less for charge time took more than one hour.
- Two batteries: Having two batteries allows you to use one battery while the other recharges. Two Ridgids charge two batteries in 30 minutes, letting you use and charge both in rapid succession. Tested models with just one battery: the Skil and Ridgid.
- Multiple speed ranges: The slower range emphasizes twisting force for driving and removing screws; the faster one (usually up to 1,650 rpm) is for drilling. Drills with one range typically top out at 600 to 800 rpm, a potential drawback.
- Adjustable clutch: This feature allows you to limit maximum torque to prevent driving a screw in too far or mangling its head. All tested drills (but none of the impact drivers) have an adjustable clutch, most with at least 16 settings.
- Work light: A built in light is handy for drilling or driving beneath sinks, under cars, and in other in dark places. Found on the Hitachi, Craftsmans, Makita, Ryobi and Bosch.
- Chuck type: A 12-inch chuck lets you use larger straight-shank drill bits than does a typical 38-inch chuck for drilling larger holes. Tested drills with a 12-inch chuck: Hitachi, Panasonics, Milwaukees, Bosch, Makita, DeWalts, Porter-Cable, Ridgids, Ryobi, and Black & Decker. The 14-inch pull type chuck on impact drivers requires a hex shaft screwdriver, socket, or drill bits.
Guide to the Ratings
Weight is to the nearest tenth of a pound for the drill or driver, battery pack, and second handle, if applicable. Overall score is speed, power, run time and charge time, handling, and noise at ear level. Speed is speed of drilling and driving screws. Power is twisting force for tightening and loosening. Run time is work per battery charge. Charge time is how long it took to completely recharge a fully discharged battery. Handling is weight, balance, and effort needed to position the head. Noise at ear denotes sound pressure, measured in decibels. Price is approximate retail and includes batteries and charger.