Impact drivers used to be tools for specialists. They were bulky, expensive, and considered a luxury for the common DIY. Nowadays, with a fair amount of manufacturers producing different models to capture a larger market share, they’ve become more compact, more inexpensive, thus becoming a vital tool for any home repairman and carpenter.
What an impact driver is used for
Oftentimes, first-time buyers or people just learning about different power tools will confuse impact drivers with power drills. This is an understandable mistake considering their similar shapes and that they both use different bits for driving screws.
The main functions of an impact driver are to drive screws and break seized bolts. However, with the right bits, you can actually perform a wide range of jobs with just this tool on your belt.
The two main variables that play a role in an impact driver’s ability to force screws through dense materials and break the most rusted, seized nuts are torque and concussive blows. Torque, usually measured in inch-pounds or foot-pounds, is necessary for turning the screw against the resistance caused by the material. The concussive blows, measured in bumps per minute (BPM) or impacts per minute (IPM) are akin to using a bashing a hammer against the side of a screwdriver to give it added force when rotating. An impact driver can produce up to around 3,000 IPM – about 50 impacts a second!
Even though an impact driver can technically be used to drill holes, it’s not recommended since each hammer-like blow could misalign the bit, causing a slight turn or curve in the resulting drilled-out hole. It’s best to stick to a power drill to drill holes in walls or wood, but then switch to the impact driver to fill said hole with a fastener.
Types of motors
There are two types of motors fitted into impact drivers: brushed and brushless. They both work similarly in offering the power to produce speed, torque, and quick impacts when fitted into an impact driver. We’ll explain briefly what brushed and brushless motors are below.
Brushed DC motors have been around since the early 19th century and are still found in many types of power tools to this day. A typical brushed motor consists of “stator” magnets and a “rotor” coil connected to the commutator. The current coming from a DC power source is transmitted to the coils via metallic brushes which spin with the rotor.
Brushless DC motors are powered by a DC power source through a switching power supply. This generates AC electric signals which then cause the motor to start. The magnets in a brushless motor are permanently fixed onto the conductors found on the stator. You won’t find any metallic brushes in a brushless motor (obviously).
Brushed vs. Brushless
Now that we know the basic differences in construction and how the power is delivered let’s look at some of the areas that can help you decide whether to opt for a brushed or brushless impact driver.
Although breaking nuts and driving screws may not necessarily need high speed, there is a considerable difference in how brushed and brushless motors can alter the how quickly or slowly the tool’s chuck can spin.
Brushed motors usually have limited speed ranges. This is due to the construction of the metallic brushes which prevent the motor from ramping up. Brushless motors, on the other hand, due to their lack of brushes, are not as limited in reaching super-high and super-low speeds. Power loss due to physical contact between components within the motor is virtually nonexistent.
One of the biggest problems that plague a power tool’s motor is heat. Impact drivers naturally produce heat, and pulling the trigger a bit too long without releasing it can lead to tragedy, i.e., a broken tool or one in need for major repairs.
Brushed motors produce considerably more heat due to the constant contact of the brushes against the commutator. When this occurs, you need to release the trigger and leave the tool alone until it’s sufficiently cool enough to begin work anew.
As for brushless motors, without any of those brushes in the way, less heat is produced (some manufacturers say between 50 and 80% less heat production), allowing you to get more work done. Brushless motors, although they can heat up, also deal with overheating much more efficiently. Cooling a brushless impact won’t take as long as a brushed model would.
Brushed motors require frequent visits to the tool-repairman. This is because the metallic brushes can become worn out after excessive use. You can also replace the brushes on your own if you can find and follow the right tutorial. Basically, a brushed motor needs you to be constantly aware of the condition of the brushes.
Brushless motors, with their lack of brushes, aren’t in need of constant maintenance. There’s nothing to wear out, and you can essentially get work done constantly without having to ensure sensitive components within the system are still in working order.
Brushless power tools are almost always more expensive than their brushed counterparts. Brushless motors are basically the new tech on the block in the world of power tools, thus requiring you to have slightly more financial flexibility. Brushed motors have been around since before World War I and oftentimes come with cheaper price tags.
However, whatever savings you’d hope to get from getting a brushed motor will most likely go back into fixing the tool and replacing its brushes. In the long run, if you don’t plan on retiring you power tool after its warranty is up, you’ll most likely end up spending more on a brushed impact driver than on a brushless one.
So which should I get?
Ultimately, it depends on what you’re doing and how often you’ll do it. If you find yourself in your garage workshop all day long, putting things together and tearing them apart with an impact driver, then a brushless model would be the tool of choice. Meanwhile on the other side of the spectrum, if you need an impact driver to drive fasteners every time to take an annual family portrait, a brushed impact driver with its cheaper price tag will suit you just fine.
3 Recommended Impact Drivers
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- BL Brushless motor delivers 1, 500 inches pounds Of max torque
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