The miracle of the impact driver
When they first appeared years ago, impact drivers were very popular in Japan, but it took a while for Americans to realize just how much of an advantage impact drivers have over a power drill when it comes to driving long screws into wood. especially on terraces. American companies like Porter Cable caught on to the idea and began to compete with impact drivers offered by foreign companies. The idea of impact drivers was born long ago with the inventions of (1) the impact wrench, which is used in every auto shop, and (2) the hammer drill, which is used to drive masonry bits into concrete. and other extremely hard materials.
The technology that allows them to do this is sometimes called a “hammer and anvil,” which means that, unlike the simple twisting action of a power drill, the impact driver literally “knocks” the tip of the driver as if it were repeatedly struck by a hammer. This action gives these woodworking tools tremendous power that simply wouldn’t be possible if the same screwdriver bit was put into a power drill with the same size motor and battery. An added bonus is that hex shank bits are available so your impact driver can double as a quick-change cordless drill, making it one of your most versatile woodworking tools.
The first time I picked up an impact driver, a Makita 12 volt, I thought it looked like a toy. I then tested it by driving a 3-inch deck screw into a 4″ x 4″ piece of fir. I was amazed to see (and feel) the tiny machine effortlessly drive the screw into place, sinking the head below the surface of the wood. I had to remember to keep a lot of hand pressure against the tool so the tip of the screwdriver wouldn’t come off the screw head and ruin it. From that moment on, I have never been without one of these amazing machines by my side.
Over the years these controllers have been improved to the point of near perfection and this includes the batteries that power them. Battery size has increased from 9.6 volts to 18 volts and more. More than that, battery life has been greatly extended with the advent of lithium-ion technology and subsequent improvements. In fact, a major part of the cost of any impact driver, whether from Makita Tools, Bosch or DeWalt, is the battery or batteries that come with it.
You may have noticed that most manufacturers of cordless woodworking tools have started selling so-called “bare tool bodies”, which means they come without a battery or charger included and at a greatly reduced price. The reason for this is that most (but not all) manufacturers have discovered that if they run all of their tools on the same 18 volt lithium ion battery, they can sell more tool bodies while also insuring your customers your brand. End users love this because they don’t have to keep spending their hard earned money on shelves full of different batteries and chargers, but can simply buy the woodworking tools that share the same battery.
Several manufacturers such as Makita Tools have included two or more speed ranges in their impact drivers. Sometimes too much power is not always a good thing. It can destroy the small screw heads and break the screw shafts. The more power used, the less battery life. Just because you have a 400 HP engine under the hood of your car doesn’t mean you drive around town on the gas pedal.
While a 12 or 14.4 volt impact driver will suffice for most jobs, an 18 volt model is well worth the small price increase.