An impact driver is a high-torque tool, specifically designed for driving screws into difficult materials like dense lumber and light masonry. The impact pressure is applied rotationally and works on the same principle as using a hammer to tap the end of a wrench to loosen a stuck bolt.
However, an impact wrench applies about 50 impacts per second, faster than a person could ever do, which allows them to be very efficient and drive screws and fasteners without slipping or stripping.
Since an impact driver already has this powerful rotational motion, it seems like you should also be able to use it to drill as well as drive. This would be a great solution for many projects, reducing the need for two different tools for drilling and driving, and saving time and energy. But can you use an impact driver to drill? Let's take a closer look.
Why You Shouldn't Drill With an Impact Driver
It's amazing how effective impact drivers are and the amount of runtime they get for just about any conceivable task is astonishing. But while they are an asset to have as part of your tool collection, they have their limitations too.
One of the most obvious design traits you'll notice about an impact driver is that it doesn't have a chuck. Corded power drills or cordless drills feature this characteristic to allow for larger drill bits to be utilized. While this may seem like a disadvantage with impact drivers, the lack of a chuck is actually a strength when it comes to screwing or fastening.
As you may have guessed, drills are, well ... made for drilling. Drills have a lot of features that can make them more ideal for drilling than impact drivers, including:
Impact drivers don't have a clutch
Drills have clutches, which allow you to control the amount of torque you're producing when you drill holes into materials. This prevents over-drilling and creates a clean, precise finish.
Impact drivers require specialized bits
Not only do impact drivers have hex shanks, which drills typically do not, but the repetitive percussion of an impact driver is harder on bits. Impact driver bits are specially designed to withstand this stress over time, and using drill bits in an impact driver may cause hazardous failure.
In other words, if you do decide to drill with an impact driver, you will have a narrower selection of bits, and reduced precision and accuracy when drilling.
When You Can Drill With an Impact Driver?
That being said, you can drill with an impact driver. In fact, there are some cases where an impact driver is a slightly better tool for drilling than a drill.
One thing to keep in mind about an impact driver in comparison to a cordless drill when it comes to drilling is that impact drivers, unlike cordless drills, do not have a chuck. This means you're limited with both the attachments and drill bit sizes you can use with an impact driver when compared to a cordless drill.
That said, here are some times when it is okay to use an impact driver to drill:
When you only need to drill a general-purpose hole
If the hole you're drilling does not require precise placement, size, or roundness, then you can go ahead and use an impact driver.
If you're fixing copper saddles to an internal wall or need to drill a hole through some cement sheet to run some electrical cables, there would be no harm in utilizing all of that power and torque to punch a few quick holes.
As long as the drill bit you're utilizing fits into a ¼ inch hex shank and it's rated to be used with an impact driver, you'll be able to drill holes successfully.
When boring larger-diameter holes
Some woodworkers swear by using an impact-ready spade or paddle bit for boring holes, because the high torque of an impact driver creates cleaner holes with less tear-out, and pose less risk of the tool twisting or slipping in your hands.
This method although unorthodox can streamline the process with boring holes for joinery work or drill much larger holes with a spade as a cabinet maker. An impact driver is a highly practical tool for these purposes due to the amount of power and torque output they generate.
Do I Need Special Bits For an Impact Driver?
Driving screws with a cordless drill compared to a cordless impact driver is a different ball game. Your standard drill bit isn't manufactured to withstand the same level of torque and power that an impact driver delivers. So if you plan on using the relatively expensive bits you've been accumulating, you might end up bitterly disappointed when one of them damn near disintegrates.
Specialty impact driver bits have two distinct advantages in comparison to standard driver bits. An impact driver bit has far superior torsional strength and an increased breaking angle to maximize it's flexibility and cushioning while under impact. This is attained by the design of the shank and a specially engineered tip that transfers the excessive stress and vibration from the tip of the bit to the extended torsional zone.
This design dramatically reduces the fatigue that would normally be sustained by utilizing a standard driver or drill bit with a high torque impact driver. While you can go-head and use a standard bit with an impact driver, it may end in despair and disbelief.
Things to Remember When Using an Impact Driver to Drill
In other words, you can use an impact driver to drill, but you will usually have less control, less precision, and fewer options for bits than when using a drill for the same job.
When using an impact driver to drill, getting the right bits is essential. The best thing you can do is to get drill bits specifically designed for an impact driver. While impact drivers have a smaller range of available bits than traditional drills do, using the correct, impact-ready bits will keep the driver from wearing or breaking bits, and will improve your results. Using the wrong bits in an impact driver can be dangerous.
Fortunately, more and more manufacturers are coming out with drill bits that are “impact ready,” and can be used in both impact drivers and in drills with hex shanks. These bits are also quick-change, since impact drivers don't have a chuck that can take longer when changing bits.
Some purists will say that you should never use an impact driver to drill, but the truth is that there are many circumstances where you can. And if you have an impact driver, it is simply too useful and powerful a tool to not take full advantage of its capabilities. With more and more manufacturers coming out with drill bits that are designed for impact drivers, there are fewer reasons not to use an impact driver as a drill on the occasions where it is useful.
If you do a lot of drilling or need specific depth, precision, and roundness when you drill holes, then you should always use a standard drill for the job. But to drill a few quick holes in a hurry, simply switching your impact driver to the appropriate bit will get you out of trouble.
Some might consider owning both cordless drill and cordless impact driver a luxury and not a necessity. Although, once you've experienced the level of efficiency wielding both power tools simultaneously, you'll never understand how you operated without both a cordless drill and an impact driver.