Electric Motor Build – Make a simple electric motor

I’m going to show you how to build a simple electrical motor and explain how it works. You can even download my design files and 3D print your own using our sponsor, PCBWay. I’ll leave a link in the video description for you.

When we apply a voltage to the motor’s electrical terminals on the commutator, it begins to rotate. As we increase the voltage, it rotates even faster. So how does it work? This simple electrical motor consists of the following parts: the base, which holds everything together; the stator, which remains stationary and holds the magnets in position; the supports, which contain bearings to hold the rotor and shaft in position and allow smooth rotation; the shaft, which sits between the two bearings and rotates; and the rotor, which is attached to the shaft and has a coil of wire wrapped around it. The ends of the coil connect to two separated metal plates known as the commutator.

There are two wires lightly touching the commutator plates, and we use these to apply a voltage to the coil. When we connect it to a power supply, the electrical current travels up the wire and into one of the plates, flows around the coil, and out the other end. This causes the whole assembly to rotate. The motor rotates because of the interaction of the different magnetic fields between the rotor and the stator. We know that magnets interact: alike ends will repel, and opposite ends attract.

We can cause a magnet to rotate by moving another magnet close to it, causing a repulsion or attraction. When we pass an electrical current through a wire, we also create a magnetic field around the wire. If we reverse the direction of the current, we reverse the magnetic polarity. We can see this by placing some compasses around the wire and passing a current through it; the magnets will rotate and align. If we reverse the direction of the current, the compass needles also rotate.

If we place the wire between two magnets, the magnetic field of the wire will interact with the permanent magnet, causing the wire to move due to this interaction. If we change the direction of the current, the wire moves in the opposite direction. We can determine the direction of the wire’s movement using Fleming’s left-hand rule.

As an added bonus, you can also download my free guidebook for this; links are down below for that. If we hold out our left hand and point our thumb upwards, our first finger straight ahead, and our second finger perpendicular to the first finger, the second finger points in the direction of conventional current (from positive to negative), the first finger points in the direction of the magnetic field (from north to south), and the thumb points in the direction the wire will move.

In this example, the current is flowing towards us, and the magnetic field is going from left to right. With our hand aligned, our thumb points upwards, so the wire moves upwards. If the current flows away from us, we need to rotate our hand to align with it, and we can see that our thumb now points downward, indicating the wire will move downwards.

If we wrap the wire into a coil, the magnetic field becomes stronger. Each wire produces a small magnetic field, but these combine to form a much larger, stronger magnetic field. We can place a compass at either end to see it forms a magnetic pole. We can reverse the magnetic field by reversing the direction of the current.

If we allow an electromagnetic coil to rotate freely, placing an alike pole of a permanent magnet near the coil will repel it away, while the opposite end will be attracted. It will then magnetically align and stop rotating. We could keep flipping the direction of the current so it never aligns, causing it to keep spinning.

Instead, we could improve this by spreading the coil over a wider area between two permanent magnets. Instead of rotating a battery, we could use a commutator to keep flipping the direction of current to cause non-stop rotation. Our rotor does exactly this: the wires produce a magnetic field, and when we pass a current through them, the magnetic fields are repelled and attracted to the permanent magnets. The gap in the commutator causes the current to reverse direction every half turn, preventing magnetic alignment.

By the way, we have covered DC motors, AC motors, and even how stepper motors work in detail in our previous videos. Do check those out; links are down below for that. I’ve designed this model using 3D CAD software, which we can then use to manufacture the parts, and I’ll walk you through how to build this in just a moment.

Now we are ready to turn our design into a real-world product. You can make one of these out of wood, but it looks much more professional when 3D printed. Luckily, this video is sponsored by PCBWay, your one-stop solution for 3D printing, CNC, sheet metal fabrication, injection molding, and more. Check them out; I’ll leave a link in the video description for you.

Don’t forget, you can download my design files and have these 3D printed, so you don’t need to design it yourself again; links in the video description for that.

Okay, so we head to the PCBWay website, log in, click the 3D printing option, then click on quotation, and select 3D printing. We can then upload the files we would like printed. I will select the rotor; it uploads and shows a preview on screen. We can then select the quantity and the material. I’m going to change this to PLA material, which is more expensive, but you can choose whichever material you’d like to suit your budget.

We then have some other options, but I’ll leave these as default and submit my order. PCBWay will review it, and we can then pay for our order. A few days later, our parcel arrives, and inside is our printed component. You can order all the parts, but I’m going to 3D print the remaining parts myself, as I already have a 3D printer.

For the rotor coil, I’m going to use some 0.22 millimeter diameter enameled magnetic copper wire. The enamel coating electrically isolates the wires from each other, meaning the current has to flow through the entire wire; otherwise, it will take the shortest route possible, and we wouldn’t get a strong magnetic field.

We take our wire and tie it into a knot through the hole in the rotor, making sure to leave plenty of excess wire and taping the excess to the side of the commutator. Then we start wrapping the coil in the clockwise direction. You can give it as many turns as you like, but 400 to 600 turns will work very well. I’m using 600 turns for this design.

Then just cut the end and tie it into a knot through the hole in the frame on the opposite side, again leaving plenty of excess wire and taping this down as well. Your rotor should now look something like this.

For the commutator plates, I’m going to use some 22 millimeter copper pipe and use pipe cutters to cut off a section around 20 millimeters long. Then we need to drill a hole all the way through both sides, making sure the hole is near the end of the pipe section.

Then we place the section of pipe in the vise and cut along the length of the pipe, then turn it over and cut along the opposite side. We should end up with two commutator plates. You should also clean these to improve the electrical connection.

Now take the ends of the wire and remove the enamel using some sanding paper and/or a lighter. Be careful not to snap the wire. You can now tie the wire into a knot through the hole on the commutator plate, then take some super glue and glue the commutator plate to the rotor.

I’ve placed some guidelines on the rotor to help me align this. Make sure the commutator plate is attached to the nearest side of the coil, then do the same for the other side. Using a multimeter in the continuity function, test the two commutator plates to ensure there is an electrical connection between the two plates via the coil.

Now slide the rotor assembly over the shaft from the commutator end. I’m using a five millimeter diameter stainless steel rod, which is 200 millimeters long; this will give a good tight fit. I’ve marked the base out onto some plywood, and using a table saw, I’m going to cut this out.

Again, links in the video description for my design files; you can also 3D print this part if you want. After a few minutes, it should look something like this. As you can see, I’ve also drilled some holes for the screws as well as the commutator wires.

For the support arms, I’ve gone for a dual arm design, which distributes the stresses and vibrations down into the larger countersunk screw blocks, which are joined together. The blocks are positioned away from the centerline to make it more rigid for left-to-right movement, but as the arms are connected to one half of the block, we get some spring action for back-and-forth movement.

Then we place a bearing into the holder, which will be a tight fit. We use these because if we just place the shaft into a groove, the vibrations will cause it to lose its position. So we enclose the shaft to prevent that, but there will be a lot of friction, so we use a bearing to keep it in place and rotate it smoothly.

I’m using 16 millimeter diameter bearings as I just had these spare, but there are better versions available. Then for the stator, I’ve again gone for a dual arm design, but this one uses vertical channel beams. The frame allows us to insert up to three high-strength N52 magnets.

For the assembly, we screw the front support into place and then hold the shaft and rotor in the bearing while fixing the rear support into place. Now spin the shaft to test that it rotates smoothly, then we can attach the stator arms into place. Once ready, push your magnets into position, ensuring that the north pole is facing inwards on the left and the south pole is facing inwards on the right.

If your magnets are not marked, you can use another magnet or compass to find the polarity. Then we need some wire for the commutator arms. You could use some bare metal paperclips, but I’m going to strip some single-core electrical wire and use that.

We place it through the hole and then wrap it around, bending it a little bit so it’s very lightly touching against the commutator plates. Now rotate it slowly to check that it touches each plate but isn’t touching anything during the gaps.

Now we are ready to connect it to a power supply. I’m using a DC bench power supply set at 12 volts. I place the positive on the left and the negative on the right. When I turn it on, the motor starts to rotate. We can increase or decrease the voltage to change the speed of rotation.

It spins very fast, but it’s not a very powerful motor because it’s just a basic design. Notice that we can also see some sparking occurring on the commutator, especially with the lights off. This will damage the surfaces over time, so play around with the unit and try to keep this to a minimum.

There are lots of ways to improve this basic motor; let me know your ideas for improvements in the comment section down below. Check out one of these videos to keep learning about electrical engineering, and I’ll catch you there for the next lesson. Don’t forget to follow us on social media as well as the engineeringmindset.com.