Introduction: Capacitor Car
Our project was given to us by our engineering teacher in class, and was to build a capacitor powered car, which could travel down our school hallway with a minimum distance of 75 feet. With this project came several restrictions which included material availability and the type of materials. We were only allowed 6/10 of a cubic inch of 3D printing material to print our chassis, and every group had to use the same capacitor, same voltage of charge, and the same motor. In our class, there were groups of three, and each group of three worked on different parts of the car to put the final project together and test it.
Step 1: The Gears
One out of the three major components of the capacitor project was the gear portion. Our teacher had given us a recommendation to have a 3:1 ratio of gears before the project had started. He based this hint off of past years' winners for the farthest traveling car. My group had to build these gears in Solid Works, and then input them into an assembly to make sure they mesh. After we determined they meshed, we saved them as an .stl file to be 3D printed. The gear ratio which we chose was approximately 2.42:1 with the 14 tooth gear on the motor and the 34 tooth gear on the axle. The axles were both stainless steel. The diameter of our axle was .16 inches and the diameter of the motor shaft was .078 inches. Both gears were 32-pitch gears. We printed the gears with no center hole to press on, so we used a lave in our shop to find the center of each gear and drilled each to the size stated above. These gears could have been changed due to the adjustment design on our chassis.
Step 2: The Chassis
As stated earlier, for this chassis, we were restricted to only 6/10 of a cubic inch of 3D printing material which is ABS 40 plastic. This was designed in solid works to meet our needs and was continuously checked throughout the drawing of it for any weak spots and the amount of material that had been used. In the end, the chassis came to .42 cubic inches and came out strong and everything was able to bolt right on. To make sure this chassis worked, we made Solid Works drawings of the wheels, motor, wheels, and gears to make sure everything would work as proposed. This all went smoothly. The arch which protrudes upward from the base of the chassis is the motor mount which accounts for adjust ability. The axle holes were drilled out by us with a drill bit with a diameter of .16 inches and then filed down and lubricated to eliminate as much friction as possible.
Step 3: The Motor and Circuit
We were provided a silver motor pictured above which came with the two wires which are attached to it. The crimped on the blue connector seen in the pictures we soldered on the limit switch to the normally closed port so that when we were to run our capacitor car, we would hold the metal flick switch down to open the circuit until we started our car by letting it go. Our capacitor is a 5 volt, 1 farad aerogel PB series capacitor which we connected the positive terminal to the the blue connector and the negative to the power port on the limit switch. If you wanted the car to go backwards, all you would do is flip the leads of the capacitor. The two bolts seen above were cut to comfortable size to mount the motor onto the chassis due to their 1 inch length.
Step 4: The Wheels
The wheels were previously provided and the dimensions of the wider wheel were .675 inches wide, and 1.55 inches in diameter. The dimensions of the narrow wheel were .2 inches wide, and 1.37 inches in diameter. The boss on each wheel was drilled to axle size and pressed on by hand. The boss extends .2 inches out from the back of the thick wheels and the boss extends out .2 inches from the narrow wheel.
Step 5: The Final Prouct
In this picture, the final product, the capacitor is shown but the only thing you may see odd is that the rear wheels were swapped with narrow wheels, the axles were cut and sanded to size, and the gears are flopped. When you are to build this, flip the gears as to how specified earlier in this instructables. Also the capacitor is unfortunately not shown in this picture but the positive end of the capacitor would be attached to the blue connector on the white wire, and the negative side of the capacitor would be attached to the power port of the flip switch. Thanks for tuning in!