Balloon Car: a Combination of CNC and 3D Printing Technologies

We made a balloon car in our Independent Study. It was based on the CNC machine we built

• CNC Machine (Not necessary, the car can be 3D printed)
• 3D Printer with filament
• Material to cut (if you use the CNC machine)
• Experiment with different materials and manufacturing processes

We designed our car in Onshape but it can be done in any 3D modeling software. The most important thing to remember is to make your car the same height as your material. This will ensure the whole car gets cut out properly. To do this, just import the STL into the 3D Slicer software or cutting software. Once it has been imported, resize it to the correct dimensions. Make sure your axle is a tiny bit smaller than the hole bored into the car.

If working in a group: Have another person design an axle and wheels for the car. This will teach you how to collaborate with others when creating a final product.

For this step, we will use the CNC machine or 3D printer to make the car. If you decide to use a CNC, try to experiment with many different types of materials. Some materials may work better than others. We used Easel by Inventables to cut our car but you can use whatever software you are most familiar with.

CNC: If you decide to use Easel, make sure to set the correct bit size and correct Z-axis height before cutting. If these are not correct, the car will not come out right... The use of CNC machining means that your car will not include the holes for the axles. So that hole will have to be drilled out later by hand (make sure there is a drill bit the right size that will match your axle)

3D printing: Make sure your slicer settings are correct for the type of material you are using. Ensure your bed is level and that you have good adhesion. (If not, take a glue stick and rub it on your print bed)

Even if you decide to use CNC machining you will still have to print your wheels, balloon holder, and axles separately so that they can be assembled later. The balloon holder will have to fit in the premade hole on the car for it to work effectively. Remember, iterate on your designs. If one thing doesn't work, then try something new or improve upon your past designs.

If you used CNC Machining as your manufacturing method of choice, now is the time to drill holes into your car body for the wheel axle. Do this by clamping it down into a vice and using a correctly sized drill bit to drill the holes. Next, You want to drill a hole in the back to allow the air to escape. Try with different size holes and at different angles until you get something you like.

Now you get to assemble the car that you have designed and build. Put the axles through the hole in the car's side and put wheels on each end. Next, put the balloon holder in the hole on top and secure it with a bit of hot glue.

Finally, you get to test the car you have spent so long designing. Blow up the balloon, attach it to the balloon holder, and let it rip. If it doesn't work, try modifying your design until you get something that works.