Build a Simple Electric Motor!

Abstract

When you think of a motor, you may immediately think of a car, but you actually encounter other motors in your home every day. That's right, if you put on clean clothes from the washing machine, ate food from the fridge, or used a fan, you used an electric motor. In this electronics science project, you will make a simple electric motor with two magnets that "talk" to each other. As they interact, they will alternate between "liking" each other (pulling together), and "disliking" each other (pushing away from one another). All that pushing and pulling will create some serious spinning and that is exactly what a motor is, a spinning axle.

Objective

Learn how to build a simple electric motor and study how simple changes affect the motor's rotation.

Introduction

What do windshield wipers, CD players, DVD recorders, blenders, ice makers, laptops, and walking toys have in common? They all contain electric motors. In fact, you can walk through your house and find many electric motors hidden in electrical devices, appliances, and toys in every room. The electric motors are not always obvious in devices, and you might need to do some background research about how the devices work to discover where their motors are hidden. Electric motors are an important, and even vital, part of our world today.

Materials and Equipment

Magnet wire, enamel-coated, approximately 50 inches [120 cm]. This quantity allows for recoiling a second coil if needed.

Jumbo paper clips (2), metallic, 1½–2 inches [2.6 cm] long
Sandpaper, fine-grit
Neodymium magnets (3), 1/4 inch [0.6 cm] diameter
Compass (1)
Booklet
A dowel or other cylinder, 1/2 inch [1.3 cm] in diameter, such as the cap from a large felt-tip marker. As an alternative, tape four pencils that have free ends (no erasers) together (such as colored pencils), as explained in the Procedure
Ruler or measuring tape
Scissors
Piece of cardboard, 2 x 3 inches [5 x 8 cm]
Battery, C cell (2); though you may only use one, it's a good idea to have a second one on hand, as it is likely you will drain the first while tinkering.
Tape (electrical tape or masking tape works best)
Lab notebook
Building the Electromagnet
1. If you have a cylinder with a diameter of about 1/2 inch (1.3 cm), you can skip this step. If you are using pencils, tape four of them in a bundle, with the tips on one end and the free ends on the other, as shown in Figure 6, below.

From one end of the magnet wire, measure about 1.6 inches (4 cm), and from that point onward, wind the magnet wire 10½ times around the cylinder or taped pencils. Cut the magnet wire with the scissors, leaving about 1.6 inches (4 cm) free (uncoiled) at each end.

The magnet wire must be neatly and evenly coiled. If it is not, the weight may not be evenly distributed, making it difficult for the electromagnet coil to rotate in the final motor setup. Try to ensure the loops are touching each other, always parallel to one another, as shown in Figure 7, below.

Carefully slide the loops of magnet wire off the pencils or cylinder. Your coil might look circular or square, as shown in Figure 8, below. How to hold the loops together is explained in step 4.

Keep the loops bunched together to form a tight coil:

Thread each free end of the magnet wire through the loops of coil in the 3 o'clock and 9 o'clock positions, as shown in Figure 9, below. If desired, you can knot the magnet wire to help the coils stay tightly bunched.
The free ends of the magnet wire should form a straight imaginary line through the coil (the imaginary line connects the 3 o'clock and 9 o'clock positions and runs further along the free ends). The free ends will be the axle upon which your electromagnet (the coiled loops of magnet wire) spins.

The magnetic wire is protected with electrically insulating enamel coating. As explained in the Technical Note, below, this electrical insulation needs to be removed from the ends of the axles to create electrical contact between the axle and the axle support. It is important to be thorough about stripping off the insulation. Practice stripping off the enamel insulation on a practice piece of wire before doing it on either the right or left axle.

To strip only the top half of the insulation off the end of a practice wire piece:
1. Lay one end of the wire on a piece of cardboard (to protect the table underneath) at the edge of a table or counter. Hold the other end of the wire in your hand. Figure 10, below, shows how you should hold the coil when stripping the top half of the insulation of the axle.
2. Rub the sandpaper over the wire to remove the top half of the insulating material from the magnetic wire.
3. The insulating coating is removed when you can see the copper wire underneath.
To strip all the insulation from the end of a practice wire piece:
1. Fold the piece of sandpaper in half, with the rough sides facing each other, to make a "sandpaper sandwich."
2. Put the end of the magnet wire that you want to strip inside the sandpaper sandwich, as shown in Figure 11, below. While softly pressing the sandpaper sandwich together, gently rub it over the wire, back and forth.
3. Give the wire a quarter turn and rub some more to remove the coating on all sides of the wire.
4. The wire is stripped when you can see the copper wire underneath.
5. Be careful not to press too hard when rubbing or the wire could break.

Now that you are done practicing, carefully strip the insulating material off the top half of the end of the right axle, as shown in Figure 12, below. Note: This is an important step, so try to be precise!

An easy way to strip off the insulating material is to hold the coil between your thumb and forefinger so it is standing upright (perpendicular to the floor) and then hold the coil off to one side of a table, as shown above in Figure 10.
Strip the coating by rubbing the sandpaper over the axle, as you practiced in step 4.a. Note : Only the end of the axle needs coating to be removed. The first centimeter (3/8 inch) of the axle (closest to the coil) does not need to be sanded.
Do try to remove all the coating on the top side of the wire. You should be able to see the bare copper wire.

Flip the coil around and sand the end of the left axle. On this side (the left axle), remove all the coating, as shown in Figure 12, below. Note: This step is important as well, so try to be accurate.
1. Strip the coating by rubbing the sandpaper over the axle, as you practiced in step 4.b. Note: Only the end of the axle needs coating to be removed. The first centimeter (3/8 inch) of the axle (closest to the coil) does not need to be sanded.

So far, you have built the electromagnet. Now you will build the base and hook it up to the battery so that current can flow through the coil.

Building the Axle Supports

Bend the inner part of each of your two paperclips open to create the structure, as shown in Figure 13, below. Basically, gently lift the shorter section of the paperclip and slowly move it upward (like a clock hand), counterclockwise over the longer piece, until it is in the 12 o'clock position, with the original longer section still in the 6 o'clock position. The paperclip should now look like an elongated number 3 with a tiny, more or less circular, hole in the middle.

Use tape to secure one paperclip to the positive end of the C cell battery, as follows. Note that electrical contact is created between the axle support (paperclip) and the battery terminal.

Stand the battery upright so the positive side faces up.
Place the bigger loop of one paperclip such that the metal goes around the bump on the positive side of the battery, as shown in Figure 14, below.
Secure the paperclip with tape, as shown in Figure 14. Do not cut the tape yet.

Secure the other paperclip to the negative end of the C cell battery. Note, also on this side, that electrical contact is created between the axle support (paperclip) and the battery terminal.

Turn the battery over so it rests on its positive side, the side to which a paperclip is already attached.
Place the bigger loop of the second paperclip such that the metal lies on the side of the bump on the negative side of the battery, as shown in Figure 15, below. Be sure to align the second paperclip with the first, both pointing away from the battery in the same direction.
Use the tape to hold the paperclip in place.
If needed, to create a secured structure, you can wrap the tape around the battery a second time before cutting it.

Your finished support system can be balanced in the fold of an opened book (such as the booklet that came with your Science Buddies kit), as shown in Figure 16, below.

Building the Electric Motor

Time to put it all together! Let Figure 17, below, be your guide.

Open the booklet that comes with the kit (or any other book) and balance your battery and its attached axle supports in the fold of the booklet, axle support facing up, as can be seen in Figure 17.
Place three small cylindrical neodymium magnets, one on top of the other, on the battery in the middle between the two axle supports.
Insert each axle end into a loop of the axle support. Your motor might well start running right away! Wow! Great job!
In case your motor needs some fine-tuning:
1. Adjust the axle supports so the axle is horizontal.
2. Give the coil a few turns to make sure it can spin freely and does not rub against the magnet.
3. Turn your coil 180 degrees, as maybe the uncoated side of the axle was facing up, not touching the axle support. Contact of the bare wire with the axle support will create an electrical connection and allow current to flow.

In case your motor is still not running, try the following troubleshooting tips:

Gently flip the electromagnet (the wire coil) back and forth to make sure that it can easily rotate 360 degrees. If it cannot, it is probably because the weight is not distributed evenly, and you will need to tinker with the loops of the coil (or even re-coil the magnet wire) until it can rotate smoothly.
Evaluate if current is flowing through your electromagnet. Remove the permanent magnets, bring the compass close to your coil, and see if the compass needle moves. Shake your compass and see if it will align again. If it does, go to step c. If it does not, rotate your coil 180 degrees and evaluate if current is flowing in that position. If it is, go to step c. If it is not, there is no current flowing through your electromagnet. Try these tips:
1. Make sure no insulating material is left on the stripped parts of the axles that are in contact with the axle support. If you have a magnifying glass handy, it might help you evaluate if coating is left on the stripped parts. Small leftover pieces of coating can inhibit current from flowing through the electromagnet. Remove leftover coating where needed and try again.
2. Make sure your battery is fresh. This motor—even one that is not rotating—will drain a battery quickly as soon as current can flow.
  1. If you have a multimeter, consult the Science Buddies reference How to Use a Multimeter for guidance on how to use it to evaluate the battery. A full C cell battery should provide a voltage in the range of 1.3–1.5 volts (V).
  2. To evaluate your battery without a multimeter, use another paperclip to create an electrical connection between the two supports, as shown in Figure 18, below. Unfold the paperclip so it can span the distance between the 2 axle supports. Use it to connect the axle supports for a short time to evaluate with a compass if current flows through that connection, as you did in step 4.b. of this section. Important: Do not leave this connection on for long; it will quickly drain your battery!
3. Check that all electrical connections are tight as the current can only flow if there is a complete path (a closed circuit); in this case, from the positive to the negative terminal of the battery. Make loose connections tight and try again. Figure 19, below, indicates the electrical connections in your motor.