This is one of the most popular workshops we do in MAKESHOP.
It's a simple propeller powered car which - if built correctly - can go really fast.
The car in this Instructable is made from garden bamboo, because I like working with bamboo, but you can just as easily use stiff cardboard, foam board, balsa or anything suitably light and stiff. There are some alternative designs and materials at the end of this Instructable.
You can also make the car into a different shape, decorate it and add bodywork; so consider this as guidance to building a working chassis. Bear in mind that if it's heavier it will not accelerate as quickly.
Step 1: LET'S GET ORGANISED
You'll need a few bits and pieces to build this one. A reasonable hobby shop should have what you need. We sell kits in MAKESHOP.
- Material for car body/chassis; We're using bamboo
- Toy wheels and - optional - tyres
- Appropriate dowel or bamboo skewers to use as axles; We used 4mm dowel
- Drinking straws to hold the axles
- A high speed hobby motor. The small 3 Volt ones with flat edges are what you want.
- A propeller/fan to be fit to the motor. We use these blue ones but the more common three bladed black plastic ones work really well too
- A piece of something light to hold the motor high enough; Here we're using a plastic shot glass, you could use a cork or a chunk of foam
- A switch
- A 2X AA/LR6 battery holders
- Hot glue gun
- Strong wire cutters to cut dowels/bamboo skewers
Step 2: LET'S BUILD THE CHASSIS
In this Instructable I've used garden bamboo, but you can just as easily use cardboard, light wood, plastic or foam. There are a couple of examples at the end of this Instructable.
- Work out what length and width you want the car to be and cut the material to size. Here we used a hacksaw to cut some bamboo.
- I like to split bamboo in half along it's length to get two pieces of the same length that have a flat edge. Never cut towards your fingers! Note how both hands are out of the way.
- Arrange the pieces ready to be glued; the picture shows underside of the car.
- Here, we've used the battery holder itself and glued it in place to hold the chassis together.
Step 3: LET'S DECIDE WHERE THE WHEELS GO
We are using drinking straws to hold the axles. The plastic of the straw slides smoothly against the woden dowel so the wheels can spin freely. It's important to place the straws just right so that the car can travel in a straight line - unless you want it to go in circles? That's up to you!
- The propeller needs to be able to spin without hitting the car chassis or wheels. Here, we're placing the rear axle so that the rear wheels won't poke out past the back of the car
- Measure the width of the car and cut two pieces of straw so that they're 1cm or 2cm longer than the width of the car
- Put some glue on the chassis where you want to place the straw
- Before the glue hardens adjust the straws so that they are perpendicular to the body of the car; We used the help of the lines on the cutting mat.
Once you are happy with the position of the straws you can add more glue if you wish.
Step 4: LET'S BUILD THE AXLES AND WHEELS
The axles need to belong enough to go through or into both wheels and not pinch the straw.
- Measure the axles. they need to be as long as the straw plus 2 wheel thicknesses plus a couple of millimeters; We knew that our wheels were 6mm wide so we added 10mm on either side of the straw.
- Cut the kebab skewer or dowel with a pair of tough wire cutters. Watch out for flying bits of axle!
- Take two wheels and insert the axle pieces into them. Ours are a very tight fit so we tap them in with a hammer. Your kebab skewers might be a loose fit so carefully use glue to hold them in the wheel.
- Insert both axles through the straws as shown and add the wheels on the other side. make sure to leave a small gap between the straw and the wheels. Make sure there is no glue slowing down the wheels.
Step 5: LET'S ADD THE MOTOR
We need to position the motor so that the propeller has room to spin without bumping into anything. That's why we use the shot glass as a kind of stand to hold the motor high enough so the propeller doesn't hit the ground.
- Position the shot glass, or cork, or whatever you're using as a motor stand at the back of the car. Far enough back that the propeller will be able to spin without hitting anything. Glue it in place.
- Carefully put a little glue on the underside of the motor. Don't get glue in the holes; it can jam the motor.
- Place the motor so that the shaft protrudes off the back of the vehicle. You can add more glue to secure the motor after it's in the right position.
- With the propeller on the motor touch the wires off the motor terminals to check ...
- ...that the propeller can spin...
- ...which way the motor needs to spin to blow air backwards; swap the wires if it's spinning the wrong way.
Step 6: LET'S ADD a SWITCH
We don't want to have to disconnect wires every time we want to turn the car off so we're going to add an on off switch.
- Double check which wire needs to connect to which terminal of the motor for the propeller to blow air backwards. Hook the wires in and twist them so they hold in place.
- Decide where to place the switch and glue it there.
- Cut one of the wires to the motor so that you can connect the end connected to the battery to your switch. Strip the cut ends of the wire.
- Hook up the switch as shown:
- If you have a switch with two connectors, use one connector for each piece of wire. This is probably a "single pole, single throw" or SPST switch.
- If you have a switch with three connectors, connect one piece of wire to the center connector and one to one of the other connectors. This is probably a SPDT switch.
- If, like in the picture, there are six connectors on your switch, connect one piece of wire to one of the center connectors and the other to one of the connectors next to it on the same side.
Step 7: LET'S CHECK OUT SOME OTHER DESIGNS
Of course, you don't have to use bamboo!
Here are some other basic designs. Look at the cardboard car in the middle. See how the cardboard is folded up on either side? This makes it more rigid. Use the same technique to get pizza into your mouth!
Don't stop there! Add some decoration and bodywork to your car. We used some pieces of straw to make exhaust pipes and cool, hot-rod manifolds. Let us see what you do with yours!
Well done, see you at the track!