By delivering more power in a smaller, lighter weight package, cordless impact drivers are making themselves indispensible on the job site. In addition, the fastening tool can now work in a wider range of applications.
Cordless impact drivers far outperform conventional drills when it comes to driving screws. A cordless impact driver will supply as much as 1,500 inch-pounds of torque to the task, compared to just 250 inch-pounds with a conventional drill.
Impact drivers get their name from the drive gear (the hammer), which pounds the two-lugged gear called the anvil. The drive gear strikes the lugs of the anvil at a rate of up to 3,000 blows per minute when the torque needed to turn the bit exceeds the torque of the tool’s rotational force. Even with all that torque, an impact wrench is much less likely to strip screw heads than a conventional drill.
The combination of bit rotation and concussive blows provides improved screw-driving power, but requires less muscle from the user so users experience far less arm fatigue.
The speed and power of cordless impact drivers makes them ideal for driving screws into concrete, metal, decking and drywall. They are also excellent for loosening stuck screws and bolts—a problem which can quickly slow work on any job. And although their primary purpose is not drilling, an impact driver can drill holes to about 7/8 inches in diameter with the right drill bit. Like drills, impact drivers have a quick-release chuck to allow quick bit change.
“Makita’s BTD141 8V LXT Lithium-Ion Cordless Impact Driver uses a “one-touch” chuck,” says Brad Wheeler, Makita product manager. “With no need to pull the sleeve for bit installation, this chuck provides faster, easier bit changes. The BTD141 also has a built-in LED light for better visibility.”
Impact driver vs. impact wrench
The work you are doing will dictate whether you can use an impact driver with a socket adaptor or need a dedicated impact wrench. The primary difference between the two is the chuck configuration.
A dedicated impact wrench features a durable 3/8- or ½-inch square shaft designed for heavy-duty applications, such as driving large lag bolts or bolting pipe couplings. In comparison, a cordless impact driver uses ¼-inch hex-shank bit for driving screws or drilling.
Selecting an impact driver
Select a cordless impact driver with the speed and power necessary for the job at hand.
Another critical factor is ergonomics. A tool that is comfortable to operate will allow you to work longer and faster without becoming fatigued. Before purchasing an impact driver, pick up the tool and hold it to see if it feels comfortable in your hand.
Impact drivers, which are about 35 percent smaller than a comparable drill, are ideal for working overhead or in tight quarters. If you’ll be using it overhead, be sure the weight isn’t too much for you to handle. Check to see if the trigger operates smoothly and that the tool feels balanced in the position you will use it.
Other features you may want are battery power, work lights and belt clips. Li-ion batteries are more expensive than other types, but provide added power at a lighter weight. Work lights provide increase visibility in low-light areas, and some models feature lights that stay on after the trigger is released. Belt clips enable users to safely carry the tool as they climb ladders and carry materials.
—By J. Costin
Impact driver vs. impact wrench
Projects for an impact driver
- Deck building
- Metal roofing
- Drywall
- Duct work
- Light-gauge steel framing
- Cabinet installation
- HVAC installation
- Sprinkler installation
Projects for an impact wrench
- Driving large lag bolts
- Bolting pipe couplings
Captions:
2. Makita's new XT Lithium-Ion Cordless 1/2-inch Hammer Driver-Drill Kit, model BHP452A, delivers 450 inch-pounds of torque.
3. Ryobi's 18V P230 Impact Driver weighs just 3.1 pounds but delivers 850 inch-pounds of torque.
4. RIDGID MaxSelect Impact Driver works with 24V and 18V battery systems. Driver weighs just 4 pounds, but delivers 1,490 inch-pounds of torque.