Canadian Woodworking

Why You Need an Impact Driver

Author: Rich Keller
Photos: Rob Brown
Published: April May 2021
impact drivers
impact drivers

There’s no doubt that the impact driver is one of the most popular cordless tools on the market today, second only to the drill. Learn how you can benefit from having one on your shelf.


Today, most manufacturers produce a drill and impact driver kit that offers great value, even when compared to the single drill kit options on the market. But why do you need to own two “drills”? They all do essentially the same thing, right? What is all the fuss about? Is an impact just a drill with a handy quick-change chuck made to take screwdriver bits? The answer is no, it’s not a gimmick to get you to buy another drill with a different chuck.

Impacts were designed for a different reason, and there’s also good reason why pretty much every manufacturer today offers a kit with both tools inside. Even though impacts have been on the market for years now, there’s still a bit of confusion around the dif­ferences between impact drivers and drills.

Great Value
Purchasing an impact driver as part of a kit will give you great value for your dollar. Often, for only a little extra money, you will get a drill, or another power tool in the kit, and potentially extra batteries, too. (Photo by King Canada)

Heaps of Power
Impact drivers excel when dealing with large metal fasteners. You can use an impact driver with impact-ready screwdriver bits, as well as chuck nutsetters and other accessories into your driver, and sink lag bolts and a host of other fasteners.

Perfect Fasteners
Medium and large fasteners are what impact drivers are designed for. Longer #8 and larger screws and lag bolts are what comes to mind first, but there are many other types of fasteners an impact driver will sink.

Maybe Not
Shorter #8 screws, as well as smaller screws, might best be installed with a standard drill. An impact driver may provide too much power for fasteners like this. The risk of stripping a small hinge screw is high with an impact driver.

Eons ago…

Way back in the dark ages of woodworking, I used to buy cheap hardware store screwdrivers and smash the handles on them so I could put the blade into an electric drill and drive screws. Of course, the electric drill had no variable speed, and there was a bit of a coast downtime, so you had to stop a little before the screw was all the way in. And, if you needed to take it back out, it was back to hand tools. There was no reverse.

When cordless drills first came on the market, I don’t think I was the only one to start using one to drive screws. And around the same time, 1/4″ hex bits started showing up on store shelves, too. With variable speed and reverse, driving screws got a lot better with cordless drills. Now you could slow down at the end and not acci­dentally bury a screw into your project. And you could also take something apart if need be, as these drills had a reverse setting. The only problem remaining was that cordless drills really didn’t have enough torque to drive big screws. Bits would frequently slip, jump or strip out the heads of big, long screws.

Fortunately, a solution for this problem came along. Cordless impact drivers are essentially a small version of what your mechanic uses on your car. Until recently, they weren’t as powerful as what your mechanic uses.

Bring the noise

Impact drivers typically operate at a lower RPM than drills, but provide more torque. They also have a hammering action, as the name impact implies, which allows them to drive screws with ease. This hammering action helps keep the fastener rotating by jarring it rather than just turning it.

Most modern impacts will usually rotate the fastener at a high speed until there is some resistance to the rotation, then they will slow down and start impacting. Because of the hammering action, bits also tend to stay put in the screw head rather than slip or spin out. This hammering action also produces quite a bit of noise. A few manufacturers have remedied this problem by using an oil-filled impact mechanism to substantially deaden the sound. An example of this would be the Makita DTS141Z, which they call an “oil impulse impact driver,” while Milwaukee calls their model “SURGE”. Ryobi and Ridgid also offer oil-filled impact drivers.

Because of the popularity of impacts, users have come full circle now, purchasing impacts because of their compact size and adapt­ing them for drilling holes. Impacts have gained so much popularity that manufacturers are starting to make drill bits with 1/4″ hex shanks to go in these tools, but this is a less than optimum setup. Impacts can get into some smaller spaces than drills can, but their low RPM and hammering action means that holes are rough, and bits have shorter lifespans. Manufacturers have greatly improved drill bits for impacts in the past few years, but the impact driver is still rotating at a lower RPM, meaning it won’t bore a hole as fast or evenly as a standard drill will.

Why have two drills then?

Drills were never designed for driving screws. That’s why they bear the name “drill”. It’s not that a drill can’t be adapted to driving screws, but that doesn’t make it the best tool for the job. Impacts, on the other hand, weren’t designed with making holes in mind. I think all users of cordless tools would be best served to have both a drill and an impact driver in their tool box, especially given the low entry cost in most cordless platforms today.

Unless you are strictly drilling holes or strictly fastening, there is a good reason to own and use both a drill and an impact driver. I keep both handy in my shop. I use a drill for any drilling and the impact driver for large fasteners. I do still use a regular cordless drill for small screws like #4 and #6. I even generally use a regular drill for short #8 screws. This is one exception where a drill is better, as there is not a lot of torque required for tiny screws found in hinges and other cabinet hardware that I frequently deal with.

The next time you’re in the market for either a drill or an impact driver, do some comparison shopping on the kits available. I think you’ll really like what you see and will also appreciate having both a drill and an impact driver on hand at all times.

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