How an Impact Driver Works: Training the Apprentice
Impact drivers are an essential tool for any Pro. They give you the ability to apply more forceful power than a drill. Used in tandem, a cordless drill will handle hole making and an impact driver will set the fasteners. For basic screwdriving, an impact driver is the only tool you need. So let’s talk about how an impact driver works.
How an Impact Driver Works
A regular drill applies static rotational force to the shaft and, consequently, the bit. In other words, it exerts a constant pressure to rotate the chuck.
An impact driver senses when you need additional torque and creates rotational impact force with a spring, hammer, and anvil. As the motor turns the shaft, the spring compresses and then releases forcefully, driving the hammer against the anvil. This action happens rapidly – more than 50 times every second – and creates a much larger force than a drill can muster.
Here’s a way to think about it: using a drill is like setting your hands against an object and pushing while using an impact driver is like punching it. The same muscles create both forces, but the punch delivers much greater force. A punch also only impacts the surface for a brief moment while you can engage a push much longer.
Just like a punch, the impact mechanism creates a more violent action. That’s why you see few Pros using impact drill bits and spade bits. It’ll get the job done, but it’s not nearly as smooth of an experience. On the other hand, that violence is perfect for driving screws faster than a drill can. The speed of the hammer/anvil impact combined with the additional force gives you the ability to drive longer and larger diameter screws than you can expect a drill to tackle.
The icing on the cake is that impact drivers are typically smaller, lighter, and able to get into tighter spaces. They also won’t wrench violently in a bind-up like a high-torque drill. If that all sounds, well, impactful, you’re not alone – impact drivers are among the most popular cordless tools on the job site.
Knowing how an impact driver works will also help you understand when and where to choose it over a drill. Those are the little tidbits of knowledge that will help as you make the transition from apprentice to seasoned Pro.