Let's Make Robots! | RobotShop

Cheater the Pinewood Derby Car

Drives down a track

I know some won't consider this a "robot" because it lacks a brain, but it is still fun and worth mentioning.

Anyone who is familiar with Cub Scouts, Boy Scouts, or Royal Rangers has seen a pinewood derby car before. The Kits typically include a block of wood, 4 wheels and 4 metal axles or 2 pieces of dowlrod and 4 screws. Chuck most of that because you only need a couple of the wheels and the axles.

Items needed:

Paint Sticks
Hot Glue Gun
Pinewood Derby Car Kit (optional)
2 Wheels
Wooden Dowelrod
Gears (if motor is not geared)
Axl material
2 Tires with grip for back wheels
2 Bumper Switches (get at least one with the small wheel on it to use on the bottom)
4 AA Batteries with a holder
Battery Snap


The switch on the front is wired so that it is normally closed. That means current passes through it when the switch is out. When it is pushed in by the starting block on the track it kills the motors until the starting block is dropped. Otherwise it could burn the motor.100_1130%20copy.jpg

The switch on the bottom is wired normally open so current only passes through when the car is placed on the track this helps to save the batteries. Wouldn't want it running all the time or have to flip a switch manually thats boring.


I used a dremel to put a hole in the paint stick so the gears can poke through. All of the cutting was done using a dremel.


You'll notice the picture has the switch on the bottom in the middle.  The video shows it pushed to one side. I had to remount it because the track has bolts running down the middle as well as a hole near the starting gate. I had to move the sensor over or it would fall in the hole and the car would stop. That would equal about 1 inch of fun. 

Things I would do different:When placed at the bottom of the track pointed uphill toward the start line it ALMOST makes it back uphill to the start. Next time I may consider adding a 5th or 6th battery and adding a motor driver so once it gets to the end of the track it goes in reverse and drives back to the start.
Also I want to have 2 sets of gears so it has to shift halfway through the race. Since it starts off by going downhill I want to have it geared for less torque and more speed, when it hits the straightaway I want it to have a little more torque so it doesn't stop. It still finished in approx 3 seconds when the other cars took 6-7 seconds.

Edit: New video. Shows the car on the track and from the car's point of view.I should have put in new batteries it was running slow.

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jklug is back!
I just realized I forgot to thank Frits for the gears when he sent me a goody bag way back when. They have come in handy! I've got a project half way done that I want to finish and another on the drawing board. Both will use those gears. Thanks again!
video!  :D
Workin on it SHEESH! I had to post this first so I would have the link to the LMR page. Youtube just finished messing it up. Ill redo it this weekend with more footage of it in action. I hope people get the campaign orientated joke at the beginning. I'm sure the humor will be lost on all those non USA people.

This classifies as a robot. It has a brain. OKay, it's similar to an insect brain. It has instinct. It makes a decision:

IF (hit_wall = -1)

THEN GOSUB motor_off

What are you talking about? :-)


deductive reasoning, if.... then.... outcome. I think you might want to try to a limited slip differential.  Tamiya makes several models.