Synopsis: In this tool review, builder and designer Michael Maines assesses the current crop of cordless impact drivers. These versatile tools can be used for everything from light-duty work (installing switch plates) to heavy-duty applications (driving screws through sill plates). He outlines features available on cordless drivers, and a series of illustrations shows how a cordless impact driver gets its work done.

I picked up my first cordless impact driver a few years ago. I had gotten into the habit of using two cordless drills for many carpentry and cabinetry tasks: one to drill, one to drive. For reasons that escape me now — maybe the batteries had died, maybe a friend had borrowed my drills — I grabbed a coworker’s 18v DeWalt impact driver. It seemed awfully small even with the large battery hanging off the handle. As I recall, the task involved driving a bunch of 3-in. screws into framing lumber, and I didn’t see how that little drill would be up to the job. But when the impact mechanism kicked in, the screws melted into the wood like a hot knife into butter.

I’ve worked with several other impact drivers since then, and I spent a considerable amount of time trying out a broad sampling of drivers for this guide. All the impact drivers I’ve worked with blow ordinary drills away from a performance standpoint, but there are key features that set great drivers apart from good ones.

These drivers aren’t ordinary, although they can be

An impact driver allows you to apply a far greater amount of torque to a fastener or drill bit than any cordless drill-driver of any size. To achieve such a surge in twisting power, an impact driver uses a fairly complex mechanical system that operates on relatively basic…