One of the first electrical tools anyone will ever buy, is a drill. Drills are basic tools that are needed in a wide range of home improvement projects and can often double as an electric screwdriver, too.
But how much do we know about our drills? Do you know what motor a corded drill uses? Chances are that you don’t. In this article, we’ll take an inside look at the electrical side of an electric drill.
First, we’ll quickly discuss different drills you may encounter, then we’ll discuss the different motors you can find in them, and finally how to diagnose your own corded drill.
Is there a difference between a corded drill and a battery-driven drill?
First, let’s get something out of the way. There is no real difference between a corded drill and a battery-driven drill. The one difference you may come across (and that may have crossed your mind when you read that statement) is that corded drills are generally more powerful.
If you have a hammer drill, for example, you pack more power than with a general entry model. Because of this higher power, most of these drills don’t come with a battery pack.
While the battery would work for a little bit, the power demands of the drill would drain it so quickly that manufacturers stick with the cord.
While it is true that these corded drills have more power, they do not have a different engine. Both versions of a drill work with a brushed DC motor.
To learn more about what a brushed DC motor is, please keep reading.
What is a brushed DC motor?
First of all, you can watch this video about DC motor
The brushed DC motor that you’ll find in any common drill didn’t get there by accident. There are some qualities to brushed DC motors that make them perfect for drills.
For anyone familiar with the differences between DC and AC, the fact that corded drills come with a DC motor is hardly a surprise. The drill is no different than any other household appliance and will run with a Direct Current (as will anything else that could run on batteries).
As we mentioned above, the brushed DC motor is perfect for corded drills. Not only is the technique of DC motors almost as old as using electricity in the house and was therefore also included in the first corded drills available on the market, the other characteristics of brushed DC motors make sure that corded drill in the future will have the same type of engine.
The first defining characteristic is that the speed control is easy to manipulate. As an added bonus, the speed control and power output are directly related. The more current you allow into the motor, the more power you get on the output side.
This is why you can choose the power on most corded drills by pressing the trigger harder or softer. If you’ve ever used a drill, you know that control over its speed can be the difference between success or failure of a hole (or screw).
That makes the brushed DC motor almost like a water faucet that you control with a trigger. The more you pull the trigger, the more current you allow going through the engine.
Because of the direct correlation between current and torque (the output), you always keep control over the speed of the drill.
Another benefit to brushed DC motors is that they are relatively cheap. When you’re a drill manufacturer, this will naturally be an appealing option, if the other characteristics of this type of engine weren’t enough reason to pick it.
Brushed DC motors were very popular for any type of electrical motor and were even used to power factories. With the advances in electrotechnics, most larger brushed DC motors have been replaced, but the unique characteristics of input control and torque control are perfect for drilling a hole or screwing a screw with your own trigger finger.
How can you test a corded drill with a digital multimeter?
If you have a problem with your corded drill, there are several things you can test with your digital multimeter to diagnose the problem.
Whether or not you can fix the problem itself will depend on your technical abilities and what the problem appears to be, but anyone can diagnose with the help of a digital multimeter.
First, make sure you have the drill plugged in to an outlet that works. Anyone who has ever worked to fix something has found themselves missing the first steps.
Then, to test the motor itself (or any small brushed DC motor), you’ll have to measure the resistance in the motor.
When you disassemble the drill, you will see a cylinder that leads to the actual drill bit. Depending on the precise model of the drill, the motor might be visible right away or tucked away inside the cylinder.
In a brushed DC motor, you will see different coils, positioned in a circle. The opposite coils on each side are connected, so to test the brushed DC motor, measure every pair of coils for resistance and see if and where an anomaly comes up.
If all the pairs are in order, it’s time to test the cord itself. Switch your multimeter to the continuity setting and place one lead on one of the prongs and the other lead on the incoming side on the drill. If the multimeter beeps, your cord is fine.
For a common household tool, the corded drill has quite a few secrets for most people. Luckily, the brushed DC motor that powers your corded drill is easy to understand.
With a minimum effort in technical skills, you can diagnose your own corded drill with a digital multimeter. As always, try to get comfortable with your multimeter (and your drill) by doing some diagnoses before a problem has actually occurred.
The better you are at handling and reading your multimeter, the better a tool it becomes.