Drafting 10 Projects

Gravity Car

One of our key projects this year was the gravity car. The objective was to design and construct a functional car using cardboard, featuring a 3D-printed axle. I successfully designed a car that demonstrated structural integrity and rolled down the track with exceptional speed and efficiency. The rear wheels were crafted from a paper towel roll and empty filament cartridges, while the front axle and wheels were 3D-printed. As a result, I was able to develop one of the fastest and most efficient cars in the class.

 

3D Printed Bath Bomb Molds

One of our projects this year involved designing and creating a custom bath bomb mold for someone we knew. I chose to design a mold for my brother, which I created using Fusion 360. The design was a soccer jersey featuring his name and number (16). To produce the mold, I used TPU, a flexible plastic. During the process, I encountered challenges with printing, as TPU attracts moisture quickly, which can damage the filament.

The bath bombs were made from a mixture of citric acid, baking powder, Epsom salts, cornstarch, food coloring, and scents. I selected red food coloring, as it is my brother’s favorite color. I also incorporated detailed elements into the mold to ensure it closely resembled his actual soccer jersey.

I am particularly proud of how the mold turned out, and I consider this project to be one of my best accomplishments in drafting so far.

 

Go – Kart

One of the problems with the engine was that there wasn’t a kill switch. So, when you started the engine there was no way to turn it off. How the kill switch works is when the engine is running, the ignition coil is sending power to the spark plug to keep the engine going. But when you press the kill switch, it connects the ignition coil wire to ground (the engine block). That makes the spark plug stop firing because the electricity is being shorted out instead of going to the spark plug. The wiring is like this:

• One end of the kill switch wire goes to the ignition coil
• The other end is grounded to the engine block
• When you flip the switch, it closes the circuit and connects the ignition coil to ground.

 

 

Rust-preventing paint is super important on a go-kart frame because the metal can start to rust if it gets wet. When you drive through puddles or if it rains on the kart, water touches the metal. If there’s no paint or protection, that water can cause a chemical reaction with the oxygen in the air and the iron in the metal, which creates rust.

Rust weakens the metal over time—it can make it flaky, brittle, and eventually parts of the frame could break or get holes. That’s really bad for safety and how long the go-kart lasts. So the rust-preventing paint acts like a shield. It keeps the water and air off the bare metal so it doesn’t start to corrode. It’s kind of like waterproofing your kart. Without it, you’d have to fix or replace the frame way sooner.

A carburetor’s main job is to mix the right amount of gasoline with air and send that mixture into the engine so it can burn and make power. Inside the carburetor, there’s a bowl called the “float bowl” that holds a little gas. A float (kind of like the float in a toilet tank) keeps the gas level steady. When the level drops, more gas comes in; when it’s full, the float blocks more gas from entering.

Air from the air filter goes through a narrow part called the “Venturi.” As air moves fast through this narrow spot, it creates low pressure, which pulls gas out of the float bowl through a tiny jet. The gas mixes with the air right there. That mixture then goes past a butterfly valve (the “throttle”), which is connected to your throttle cable. When you open the throttle, more air and fuel can pass, and the engine runs faster; when it’s closed, less mixture flows, and the engine slows down or idles.

There’s also a “choke” flap that you use when the engine is cold—closing the choke makes the Venturi even narrower so less air and more fuel get pulled in, giving a richer mix that helps the engine start when it’s cold. Once the engine warms up, you open the choke and the mixture leans out to normal.

A problem we had with the engine is that the carburetor was broken. It looked like someone had tried to overtighten the float bowl on it and the thread for the bolt snapped, we tried to repair it using a metal bonding epoxy but it wasn’t strong enough. What we had to do was replace the carburetor.

Okay, so imagine you’ve got a little go-kart style setup. You have an engine that drives a chain, and that chain wraps around a sprocket (gear) on the axle. Here’s what’s happening and why welding becomes necessary:

1. Chain to Sprocket, Sprocket to Axle
   • The chain pulls on the sprocket, trying to spin it.
   • If the sprocket is just pressed onto the axle (loose fit), it will spin freely on the axle shaft without turning the axle itself—like spinning a ring on a finger.
   • To actually make the axle turn, the sprocket has to be locked to the axle. That’s why we welded the sprocket to the axle: now when the chain turns the sprocket, the axle must turn too.
2. Wheels, Bearings, and the Axle
   • Most wheels are mounted on bearings so they can rotate around a stationary axle. Those bearings fit onto the axle but let the wheel spin independently.
   • If you leave the wheels on bearings and weld only the sprocket to the axle, the axle will turn, but the wheels will just stay still (spinning freely on their bearings) and not move the kart forward.
   • To fix that, we had to weld the wheels directly to the axle instead of using free-spinning bearings. Now, when the axle turns, it forces the wheels to turn with it—because they’re welded solidly together.
3. Putting It All Together
   • Chain pulls sprocket → sprocket is welded to axle → axle spins.
   • Wheels are welded to axle → axle spinning directly spins the wheels → kart moves.

So basically, welding both the sprocket and the wheels to the axle makes one solid piece. The chain turns the sprocket, that turns the axle, and because the wheels are welded on, they have to turn too. Without those welds, the sprocket would just spin on the axle and the wheels would spin on their bearings, and nothing would move the kart.