Rubber Band Car Project

Have you ever been doing something and suddenly things stop working? Usually at some important moment? Often it is that the batteries have died. This can be so frustrating. Have you ever wondered if it is possible to make a toy car that doesn’t need fuel or batteries? Here at STEAM Powered Family, we have shown you how to build two cars that are powered by different sources of power. The first one was the Balloon Powered Car and the second was the Water Powered Car. Today we will show you how to build another toy car, that uses another simple kind of power source – rubber bands! Who thought that a rubber band could power a toy car? Not only will you learn how to build this easy car, but you will also learn about the science behind rubber band cars and most importantly, have fun while doing it!

DIY RUBBER BAND CAR

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The Science of Rubber Band Cars

Let’s take a quick look at the science of this easy build.

When you stretch a rubber band, you’re storing energy in it. This stored energy is called potential energy.

When you let the rubber band go, the stored energy is converted into kinetic energy, which is known as the energy of motion. This energy makes the car move forward.

This simple but amazing car moves on wheels attached to an axle, which together, reduce friction, making the car easier to move. This means that the car itself can be called a simple machine.

Parts of a Rubber Band Car

Let’s look at the important parts of this amazing toy car.

Chassis: This is the body of your car. It holds all the moving parts together.
Axles: These are the rods that the wheels spin around.
Wheels: These help your car roll smoothly.
Rubber Band: This is your car’s engine. Wind the rubber band up and watch the car go!

This is a quick and easy build, perfect for the classroom, STEM club, or homeschool, so let’s get building!

Making a Rubber Band Car

Now we know some of the science and parts of a rubber band car project, let’s get building. This is quite an easy build and uses easy to find materials you likely already have in your STEM Toolkit or Tinker Box.

DIY Rubber Band Car Video Tutorial

We have created a tutorial showing you step-by-step how we built this project. If you can’t see the video below (videos often get blocked by firewalls or adblockers), or would like a higher resolution version with closed captioning, please visit the STEAM Powered Family YouTube Channel.

Materials & Tools

Double-wall cardboard (or single-wall cardboard) –old moving boxes
Thin corrugated cardboard (from a pizza box or postage box)
Glue gun and glue sticks
Ruler
Pencil
Felt tip pen (black)
Box cutter
Exacto knife
Scissors
Awl (or a nail or skewer would work too)
Side-cutters
4 old CD’s
3 different thickness wooden skewers: 1 X 3mm diameter, 2 X 4mm diameter and 1 X 4.7 – 5mm diameter
2 bottle tops (to fit into the sides of the toilet roll)
Sandpaper
1 X cable zip tie
4 x Medium to large balloons (always have extra on hand)
10cm rubber tubing or paper straws
Different types of rubber bands – long, short, fat, and thick
Brown paper tape – optional

The Templates

To make this project easier, I have created templates for you to download and use if you are a STEAM Powered Family mailing list member. This template includes the building template, a worksheet for recording your results, plus step-by-step instructions so you can do this project offline too.

Directions

Getting your pieces ready

Print out the template on cardstock and cut out the two pieces.

Trace the base template onto the double-wall cardboard twice and cut them out with the box cutter. If you only have single wall cardboard, trace and cut out four pieces.

Transfer all the positions of the dotted lines onto the side of one of the cardboard bases with the felt tip pen. These are the positions of all the wooden skewers.

Trace 8 circles onto the thinner cardboard. These will be used as wheel caps. Use the Exacto knife or scissors to cut these out. Make small little cuts around the circle to get a smooth edge. You may need to do this twice. Do not try and cut through the cardboard in one go. Adult supervision and/or help may be required for cutting all the cardboard.

Use one of the wooden skewers to make a hole in the middle of the circle template and don’t forget to use the felt tip pen to make a mark in the middle of each circle you trace.

Use the pointed end of the 4mm diameter wooden skewer to make the holes in the middle of each circle. Put these aside for now.

Use the glue gun to glue the two (or four if you used single wall cardboard) base pieces together.

Preparing the Wheels

This is an important step, as the balloons will be placed onto the edges of the CDs to give the “wheels” more traction or grip on any surface. You don’t want the wheels to spin, otherwise it will not move forward fast enough. The balloons act as tires on the wheels providing grip and traction.

Fold the balloon in half down the length of the balloon and cut off about 1cm from the top. Then cut about 1cm above the tube of the balloon.

Stretch the balloon pieces out and place them onto the edges of all four of the CDs.

You will need another set of hands to do this step, it is tricky, but with help you can do it!

Sticking the “wheel caps” onto the CD’s

Using the glue gun, glue a cardboard circle into the middle of both sides of each of the CDs. I made the circles the same size as the clear part of the middle of the CDs, so it is easier to get them exactly into the middle.

Before you stick the circles onto the CD, you may want to color them with paint or felt tip pens now.

Cutting the wheel spacers

Either using the plastic tubing or straws, cut four tiny pieces, measuring 0.5cm each, and put them aside. I used the box cutter as it gives a smoother edge, but you can use scissors too.

Putting the axles into the base

An important thing to remember is that the axles need to be able to spin easily for the car to work effectively, so you are going to use the 4.7mm wooden skewer to stretch the holes of the corrugations of the cardboard.

Look at the diagram below to see which layer you need to stretch for the front and back axles:

Push the thick skewer in and out of the hole to stretch the corrugations. Do this for the front and back axles only.

Test the axle (4mm diameter) by pushing it all the way through and twisting it. It should spin easily.

Putting the “wheels” onto the axles

Push the 4mm front axle into the hole you just stretched.

Get the rubber tube/straw spacers you cut earlier and the CDs.

Push a spacer onto the skewer.

Glue the wheel onto the axle by putting a small amount of glue into the middle hole of the CD.

Push the CD onto the end of the skewer. It should just pop out of the hole on the outer side of the CD.

Put a blob of glue onto the skewer that is sticking out of the CD on the outside.

IMPORTANT! To make sure that the CD is straight, hold it as it is drying and make sure it is in line with the side of the cardboard base. You don’t want wobbly wheels!

Cut the other end of the skewer a little shorter. You may need to sand the edge with some sandpaper. Push a spacer onto the skewer.

Put a blob of glue into the hole of the second CD and quickly push it onto the skewer, close to the spacer. There must be space between the side of the base and the spacer. The wheels and axle should be able to move from left to right easily and not rubbing against each other.

Using a side cutter, trim the excess off the skewer and put a blob of glue onto it like you did on the opposite side.

Turn the base around and repeat these steps to put the back wheels onto the back axle.

PRO TIP! Keep checking that the wheels are on straight as you are working!

When all the wheels are on test the car by gently pushing it backward and forward to see that the wheels are straight and not wobbling.

Putting in the holders for the rubber band

Cut the thinnest wooden skewer to a length that is about 1cm wider than a small hole cut out of the base.

Look at the diagram of the placement of the skewers above and see where to place this holder. Push it into the one hole until it goes in and then push the opposite side into the hole on the other side.

Put some glue around each end up against the cardboard to hold it in place. Do not get glue onto the middle of the skewer.

Turn the car around and get your cable tie. The cable tie is going onto the back axle. Put it onto the skewer and pull it as tight as you can exactly in the middle of the skewer. Cut off the excess of the cable tie with the side-cutter.

Turn the back wheels so that you can see the underside of the cable tie and put some glue to hold it in place. It should not be able to move on its own but rather spin with the axle.

Fitting the “motor” of your car

The rubber bands are going to get your car moving – like a motor!

Choose any of your rubber bands and loop one end of the rubber band under and over the skewer. Thread one of the ends through the loop on the other side and pull the rubber band tight on the skewer.

If you would like to join a few rubber bands together, see the diagram below:

If you would like to decorate your car, go ahead and do so now.

Check out our finished car!

And here is a top down view.

Driving a Rubber Band Powered Car

Now it’s time to get your new car moving!

Holding onto the rubber band in one hand, turn the back wheels until you can see the head of the cable tie facing upward.

Hook the end of the rubber band onto the cable tie.

Gently turn the back wheels and watch the rubber band wind itself onto the axle.

When you think it is wound up enough, do not let go of the back axle! You have a lot of potential energy built up that is just waiting to convert to kinetic energy and send your car racing!

Put the car onto the floor, still holding on and then… let go! VROOM!

Classroom Inquiry Questions

Which type of rubber band will make the car travel faster and further?

• a long rubber band or a short one?
• a thick rubber band or a thin one?
• a double rubber band or a single one?
• a double rubber band made of thin ones
• a double rubber band made of thick ones?

Will your car go faster or slower if you add weight?

How can you modify the design to make it more aerodynamic?

What do you think you could change to make your car go faster or farther?

Fun fact about rubber band cars

Did you know that the faster you wind up the rubber band, the farther your car will go? That’s because you’re storing more potential energy, which gets converted into more kinetic energy when you release it!

DIY Classroom Car Challenge

If you have made the balloon-powered car, the water-powered car, and now this rubber band-powered car, which car would win the race against each other?

Why not have a classroom challenge? Have your students work in teams to build either a balloon, water or rubber band powered car. We have all the instructions and tutorials available for each build. Then have a day at the races to see which car wins!

Take into consideration that each of these car designs has its strengths and weaknesses and the winner could be any one of them, depending on the race conditions and how you are judging the winners.

To make things exciting, consider judging distance and speed, and race on different surfaces.

Insights on Different DIY Car Designs

Here are the strengths and weaknesses of each car that might help your students when they are deciding which car to build.

Rubber Band-Powered Car

Strengths: Rubber bands can store a lot of energy when wound up. This means they can give a strong burst of speed at the beginning.
Weaknesses: The power from the rubber band can run out quickly, making the car slow down after the first burst of speed.

Water-Powered Car

Strengths: A water-powered car uses a flow of water for propulsion, which can give the car a continuous push.
Weaknesses: The amount of water it can hold limits how long the car can keep moving.

Balloon-Powered Car

Strengths: Balloons can provide a fun and steady stream of air, pushing the car forward smoothly.
Weaknesses: Once the air in the balloon runs out, the car will stop.

We hope that you had fun making and playing with your rubber band car.