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How Does an Impact Driver Work?

Close-up of an impact driver

A multitude of tools are available to tackle any given job, but it’s true what they say about choosing the right one: It’ll make your life much easier. And with the growing number of impressive tools on the market (and in your garage), sometimes that choice can get a little muddled. Consider drills, manual impact drivers, electric impact drivers, ratchets … the right tool depends on the job. With that in mind, how does an impact driver work, and when is the right time to employ it?

Let’s Torque About Hex, Baby

How does an impact driver work? It’s all there in the name. You’ve probably used a cordless electric impact driver before. They’re handy tools with an exterior comprised of housing, a trigger, a battery and a collet, which holds a hex bit (usually one-quarter inch). Internally, these drivers’ rechargeable battery provides power to a motor that applies rotational force to twist a spring-enabled hammer. After compression, the spring tension is quickly released, allowing the hammer to strike an anvil while still carrying a rotational force. The applies a force of impact and torque to the component attached to the collet. This means your socket or bit not only turns a fastener, but drives it in at the same time. How Does an Impact Driver Work?

Mini Driver

Like all tools, impact drivers have their benefits and disadvantages. One major advantage over drills is higher torque that doesn’t get transferred to the user. Any frequent user of a drill has experienced the kickback to your wrists when a drill bit gets stuck, but impact drivers send that force to the component on the collet instead. Compared to drills, drivers are smaller and lighter for something that delivers as much torque as they do. Lastly, its concussive punching action in conjunction with the torque makes for more efficient driving.

What you compromise in using an impact driver is a bit of accuracy and versatility. The collet only accepts one bit size, which limits what you can attach, and the punching motion makes the operation less smooth and noisier.

Punch Sunk Love

Impact drivers are best used for those jobs you’d like to get done quickly or for when you’d like to reduce your risk of stripping a head. Tightening bolts and other fasteners is a great example, as is sinking a screw into a predrilled hole. Depending on the material, drills are often the best choice to make the hole in the first place. Also, if you’re going to be using the impact driver regularly, investing in a brushless model is a good decision.

Impact drivers are a very useful tool for any home or professional garage. Once you incorporate one into your project, it will be impossible to be without.

Check out all the power tools available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on tools, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photos courtesy of Blair Lampe.

Blair Lampe View All

Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter.  In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.

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