Every now and then, we encounter individuals who struggle to grasp the inner workings of an impact driver. A truly indispensable device for professionals, an impact driver generates more force (or torque) than a regular drill bit. In a joint effort, the cordless drill takes charge of creating holes, while the impact driver sets or sinks fasteners. Interestingly, for basic screwdriving tasks, the impact driver can serve as your sole tool. So, if you’ve ever pondered how this nifty gadget operates, you’ve come to the right place.
Unraveling the Internal Workings of Impact Drivers
Before we delve into the mechanics, it’s worth noting that we won’t be retreading the ground covered in our “impact driver vs drill” article. Instead, let’s focus on exploring the internal dynamics that enable impact drivers to generate their impressive torque.
Constant Pressure vs. Impact
Ordinary drill bits apply a consistent rotational force to the shaft, which in turn transmits this force to the drill bit. In other words, they exert a constant pressure to rotate the chuck. However, as the task becomes increasingly demanding, inertia kicks in. The drill begins to resist the user’s efforts, exerting force on the hands and arms. If the drill bit gets stuck while the tool continues to function, serious problems may arise!
Impact drivers, on the other hand, operate on an entirely different principle, which makes them truly unique. These drivers deliver a rotary impact when additional torque is required. They achieve this by utilizing a combination of a spring, hammer, and anvil.
As the motor rotates the shaft, the spring compresses and then releases, forcefully driving the hammer until it drops to a position where it can strike the anvil rotationally. These actions occur rapidly, with most impact drivers delivering over 50 impacts per second. Consequently, they generate a force far greater than what a typical drill of the same size can muster.
In the image above, you can observe the hammer (right) and anvil (left) of an impact driver. The spring is concealed beneath the hammer.
Pushing vs. Rapid Punching
Here’s another analogy to help you grasp the concept: using a conventional drill is akin to applying pressure to an object with your hand, pushing it forward. On the other hand, using an impact driver is comparable to executing a swift and precise punch. Think of the lightning-fast strikes delivered by the legendary martial artist Ip Man—only without the mess. Both actions engage the same muscles, but the overall power unleashed by a quick punch far exceeds that of a push. Moreover, a punch makes contact with the surface for a brief moment, while you can exert a push for a longer duration.
Performing the same task with a standard power drill demands significantly more physical strength (not to mention the need for both hands).
When and Where Impact Drivers Excel
Due to the violent nature of the impact mechanism, many professionals tend to shy away from employing impact drivers with twist and spade bits. Although they get the job done, the experience is not as smooth.
Conversely, impact drivers prove extremely effective when it comes to tightening screws. They also tend to drive fasteners requiring high torque much faster than drills. The rapid hammer/anvil impact, combined with the added force, enables you to drive screws or fasteners of greater length and larger diameter than what a drill typically handles.
Enhanced Torque Delivery by Impact Drivers
The true essence of an impact driver lies in how it delivers torque. When confronted with lengthy ledger screws or lag bolts, nothing surpasses the performance of an impact driver.
While using standard drill bits, you can drive longer and larger bolts to a certain extent. However, as you approach the end, torque requirements escalate, necessitating a robust grip on the tool. In stark contrast, employing an impact driver allows you to effortlessly drive a ledger or lag screw all the way to the bottom using only one hand!
Smaller, lighter, and highly maneuverable, impact drivers truly shine in tight spaces.
Impact Drivers: Compact and Mighty
Adding to their appeal, impact drivers typically boast smaller dimensions and lighter weight, enabling them to access confined areas with ease. The best impact drivers on the market are under 5 inches in length! Additionally, their rotational movements are not as abrupt as those of high-torque bits. If all this sounds truly impactful to you, rest assured that impact drivers rank among the most sought-after cordless tools on every job site.
By gaining insight into how an impact driver operates, you’ll be better equipped to determine when and where it outperforms a traditional drill. Armed with this knowledge, you’ll successfully transition from an apprentice to a seasoned professional.