General contractor Tom Silva shows host Kevin O’Connor the differences between impact drivers and drills before explaining when to use one or the other.
How Drills Work
A power drill is used to drill holes into materials or drive a few fasteners. They have an adjustable chuck that clamps down on a wide range of drivers and bits and an electric motor that drives the chuck. They typically have adjustable settings, allowing users to regulate the torque.
How Impact Drivers Work
Impact drivers are similar in theory, as they can be used for drilling or driving, and they also have an electric motor that spins the chuck. However, they have a ¼-inch hex collet, which means they can only use bits with a six-sided base that snaps into the chuck. Also, Impact drivers have anvils inside that strike the chuck, providing short bursts of power for long fasteners and dense materials and preventing slipping.
Pro Tip: Tom Silva, This Old House general contractor, notes that impact drivers excel at heavy-duty fastening: “Their torque and speed make short work of many jobs.”
The tool operates much like a drill driver when starting a screw, but once it senses resistance, a percussion mechanism kicks in — delivering rotational force in rapid bursts rather than continuous torque. This is what makes impact drivers ideal for sinking deck screws, installing kitchen cabinets, and replacing garage doors without the elbow strain that comes with a standard drill.
How to Use Them
A drill should be used when drilling holes into materials and driving just a few fasteners. When switching between bits, an impact driver is more handy. Also, impact drivers should be used for driving fasteners into dense materials like engineered lumber.
Can Both Drill and Drive?
Yes, both tools can be used for drilling and driving. However, an impact driver can only accept hex-bit bases and should only be used with impact-ready bits. Drills can be used with just about any bit as long as they fit in the chuck.
Pro Tip: Tommy, This Old House general contractor, explains when to reach for each tool: “If I’m doing a lot of framing, especially if I have a lot of engineered lumber and big screws, I’m gonna get an impact driver.” But for drilling holes and driving the occasional screw, he grabs the drill driver instead.
Keep in mind that if you do drill with an impact driver, the bits must be impact-rated to withstand the hammering action. As Tommy explains on This Old House, the impact driver “will not do everything that the drill driver does” — the drill driver is “definitely more versatile.” If you’re only going to buy one tool, go with the drill driver.
