Everything to Consider When Buying an Impact Driver

Just ten years ago, cordless impact drivers were a specialty tool, rare on jobsites 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. Here’s what you need to know when you’re looking to buy an impact driver of your own.

It’s All About 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.

You might think that extreme torque would put extreme strain on your arm. Nope. For reasons Isaac Newton could explain, an impact driver actually generates fewer wrist twists than a standard driver.

Not Just For Driving Screws

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.

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 same 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.

They Can Be Really Loud

An impact driver can bring a heavy-metal drummer to tears. Wear muffs or earplugs—or get fitted for a hearing aid later in life. Your call.

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.

Use Hex Shafts Only

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.