This is a 3D-printable Pinewood Derby car featuring a ducted fan propulsion system. The design combines a traditional pinewood derby-style car with an electronically controlled fan for additional thrust.

The build uses a microcontroller to manage fan startup, ramp, and runtime. A staged throttle ramp improves launch consistency while preventing sudden current spikes. The design also includes a debounce-based trigger system to ensure reliable activation from a physical start gate.

The body is designed to fit standard pinewood derby nail-style axles and wheels. This design was used in a powered outlaw competition and finished on the podium.

⚠️ While the design meets dimensional requirements for standard Pinewood Derby classes, it will exceed typical weight limits when fully assembled with electronics.

Special thanks to Shoaib Ejaz for the 2016 Camaro model used as the base for this project:

https://www.**********.com/model/1498485-chevrolet-camaro-2016-high-quality-3d-printable-mo

🔧 Basic Build Instructions

1. Print all components

Print body, chassis, fan housing, and small parts

Remove supports and clean all mating surfaces

2. Install threaded inserts

Use heat-set inserts (uxcell M3 Heat Set Inserts Kit)

Heat with a soldering iron

Press into the designated holes

Ensure inserts sit flush

3. Assemble chassis

Use M3 screws (binifiMux M3 Countersunk Screw Kit)

Attach internal mounts and structural components

4. Install electronics

Wiring overview:

Battery → ESC (main power)

Battery → Buck converter → Microcontroller (5V)

ESC signal wire → microcontroller PWM pin

Common ground shared across all components

Route wiring cleanly through internal channels.

5. Install button system

Insert the switch (Glorious Fox Linear Mechanical Switch) into the housing

Secure with hot glue or super glue

Attach printed keycap

Wiring:

One side of the switch → 5V from the voltage regulator

Other side → microcontroller input pin

Add a 330 ohm resistor between the input pin and ground (pull-down resistor)

6. Install fan and ESC

Mount the ducted fan (JFtech 30mm Duct Fan) securely

Ensure airflow is directed toward the rear of the car

Connect the ESC to the motor and power

7. Upload code

Flash the microcontroller with the provided code

Verify ESC initializes correctly (listen for startup tones if applicable)

8. Test before full run

⚠️ Ensure all components are secured before testing

Press button → fan spins at idle

Release button → fan ramps to full speed

Fan runs for a set duration → shuts off automatically

If the fan ramps slowly or behaves inconsistently, ESC calibration or firmware may need adjustment.

⚠️ Power & Tuning Notes

Tuning parameters (in code):

idle → initial fan speed

fullThrottle → max ESC signal

runTime → duration of fan operation

stableCount → debounce reliability

Different hardware may require adjusting these values.

⚠️ Safety Notes

Keep fingers clear of the fan intake during operation

Use proper LiPo battery safety practices

Ensure all components are securely mounted before running

DO NOT connect the battery directly to the microcontroller; this will fry the microcontroller. Also, ensure good connections before attempting to run.

Pinewood Derby Car – Full Print Assembly

0.2mm layer, 3 walls, 10% infill

Original