What’s the Best Impact Driver?
Ten brushless impact drivers put through their paces.
Few power tools have risen so far so fast as the cordless impact driver. A once obscure tool that’s now an indispensable part of most tool kits, impact drivers sink screws, tighten bolts, and, with the right bits, drill holes. For this article, I tested 10 impact drivers: eight 18v models and two 21.6v models. I included the higher-voltage tools because they are roughly the same size and price as the 18v models, differing only in the number of cells inside their battery packs. All of the drivers have brushless motors, which boost runtime and allow for a more compact design. I found that all the tools I tested can sink ordinary screws, but the best performers can drive large lags and structural screws quickly. The better tools are also smaller and lighter, so they can fit in tight spaces and result in less user fatigue.
How I tested
I used these tools during a remodeling project and ran them through a series of tests to gauge speed and power. Tests were performed in the knot-free portions of a dense Douglas-fir beam. I didn’t time-test short fasteners such as drywall screws because they drive too quickly to test with a stopwatch, and in everyday use I was unable to detect any difference in speed. The shortest fasteners I time-tested were #10 by 3-in. star-drive deck screws. After that, I drove 3/8-in. by 3-in. lags. In the final test, I drove 10-in. Timberlok structural screws. With all timed tests, I used fully charged high-capacity batteries, driving seven screws with each tool, throwing out the high and low numbers and averaging the rest.
I chose not to measure run time, because with modern batteries and brushless motors it’s easy to charge depleted batteries before a second battery is dead. I also didn’t…