Introduction: Robot Racer

Hi, Welcome to my instructable !

In this instructable i will show you how to build a Robot Racer !

The robot racer is a fast, fun, easy-to-build elastic band car.

The car uses recycled tubes, bottle tops and even recycled elastic bands.

If you skim through this instructable and like it, it is entered in the Klutz Competition and i really need your vote !!
Thanks and i hope you enjoy the instructable !

Step 1: Materials and Tools

Materials :
  • 1 Cardboard tube
  • 1 Elastic band
  • 4 Bottle Tops
  • 1 Kebab/Barbecue skewer

Tools :
  • Craft knife / Scissors
  • Dremel (only if tube is really thick)
  • Glue Gun
  • Ruler

The tube can be a recycled toilet roll tube, my tube originally held a roll of kitchen foil

Post-Men drop elastic bands all the time when their doing their rounds, have a look on the pavement/sidewalk when you next go out

The bottle tops need to be larger than the tube so look on milk bottles or cleaning products !

I got my kebab skewer from my kitchen but any thin rod will do !

Step 2: Cutting the Tube

The length of your Robot Racer is up to you,

You don't want it to be huge because then it wont go very far !

My tube is 18cm / 7.1 inches long.

Once you have decided on the length of your Robot Racer, mark it out on the tube using a pencil and cut it using either a craft knife or scissors depending on the thickness

Step 3: Drilling the Holes

Now we are going to drill the holes for the wheel rod (axle) to go through.

If you have a thin tube you can use the rod itself to poke the holes. My tube was quite thick so i had to drill the holes.

If you are going to drill you will need to find a drill bit that is slightly larger (1mm larger is good) than the stick you are going to use.

Making the hole slightly larger means there will be less friction on the rod and the car will go further. !

Use a ruler to make sure the holes are in line.

Step 4: Making the Wheel Rod's (Axle's)

The rod needs to be long enough to go through the tube and out to the wheels on either side, therefore its length depends on your tube size.

My tube is 3cm wide and my axle's are 8cm.

Measure the rod against your tube, then mark out the length with a pencil and cut

Step 5: Creating a Racer Design

If you want the same design as me use the second image below, remember the image is the right size for MY tube, so..

1 measure your cardboard tube
2 open up an image editing program like photoshop or gimp
3 create a new blank image with the same dimensions as a flat version of your tube
4 stretch the image to fit

If you want to be really creative you can create your own design, either cover your tube with white paper and draw your design on, or follow steps 1,2,3 above but then create you own design !

Here are some free image editing programs just incase you don't have one :


Gimp (Mac version)

Hope that's useful it took me ages :P

Once you have your design print it !

Step 6: Adding Racer Design

We want to add the design before we glue the wheels on and put the axles in.

Now you have printed your design, cover the tube in glue, line up the design and carefully stick it on !

Use your wheel rods to poke through the paper and then insert then into the holes you have made.

Step 7: Preparing the Wheels

We need to find the center of our wheels so that we can drill a hole exactly in the middle, if the hole is off-center the car will wiggle about funnily. My bottle-tops had a little lump in the middle so this was easy for me :P.

To find the center of a circular bottle top, have a look at this instructable

Using the same drill-bit as earlier carefully drill a hole in the center of your bottle top.

Step 8: Gluing the Wheels

Now the holes are drilled in the bottle tops we can glue them to our car.

I used a glue gun to attach my wheels, you could use any glue but i chose to use a glue gun because its strong, fast and easy !

Now simply plug the wheel rods into the bottle-tops (wheels) and glue, apply a generous quantity of glue to the area around the hole. We want a strong bond so nothing is loose. Repeat this for all for wheels.

Things to remember :
  • make sure all the wheels are facing the right way
  • make sure the rods are actually in the racer, you cant put it in afterwards :P
  • make sure they are straight when they are gluing

Step 9: Rubber Band Mechanism

Ok, now on to the most complicated part of the instructable !

Basically one end of the rubber band is attached to a fixed rod and the other end is on the rear axle,
when the car is pulled back the elastic band is wound up and then when you let go it zooms off.

Steps for the front, fixed rod;
1 Cut another small section from your skewer, (same size as the height of your tube)
2 Drill a small hole in the front of your car, on the top.
3 Insert the rod into the hole
4 Loop one end of the elastic band around the rod
5 Apply glue to the end of the rod to secure it in place

Steps for the back axle;
1 Use a paper clip with a hook on the end to grab the elastic band
2 Loop the elastic band around the axle
3 Your done !

Step 10: Robot Driver

If you want to add a cool Robot head like on my racer, head on over to my paper instructables robot instructable

Once you have made the head use glue to mount it to the racer !

Step 11: Customisation

Ok, congratulations on building your Robot Racer

Now we can have some fun racing it around and customizing !

Here are some ideas :
  • Rubber bands on back wheels for traction
  • Nose cone on the front
  • Streamers on the back
  • Off road tires (notches in the wheels)
  • Different racer designs
  • Different elastic band strengths

Step 12: Thanks !

Finished !

I hope you enjoyed reading/building my instructable !

If you do make this please please please take a pic and post in the comments

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