It has been a while since my last post. That is because we have become engineers of sorts here – building race cars!
Specifically, these are AWANA race cars, which are very similar to Cub Scout Pinewood race cars. The same methods shown here can be applied to making pinewood derby cars, so stick around if this is the case for you! This article will be updated as we progress through the process, so be sure to check back often.
The fist thing we did was to expand the wheel base. If you look at the kit images above, you can see the wheel slots that are cut by the manufacturer. The biggest undertaking that can be made is to place the center of gravity as far back as possible – which is about 3/4″ in front of the rear wheels. So, if you expand your wheel base, you can place your weights much further back than you could otherwise. I am sorry I don’t have images of this because I decided to document this well into the engineering process. Simply, we used a 3/32″ drill bit chucked up into a drill press. The holes were drilled such that the wheel edges were almost flush with the rear and fronts of the cars. Also note that one of the front wheel holes of each car was raised slightly higher than the other; we want the car to ride on three wheels instead of four – more on this later!
Next, we cut down the blocks down, sanded them, and then painted them with spray enamal. The maximum weight of the cars is 5 ounces (141.748 grams), so we had to cut off a lot of wood from the blocks because they were well over the max weight. Note also that we had to cut out a lot of material in the front of the cars in order to push the center of gravity towards the back of the car:
The wells you see in the back of the car are for adding lead pellets later in the process.
Side view of the cars – do you see how the front wheel hole on the blue car is higher than the hole on the orange car? The hole on the right side of both cars is 1/16″ higher than the left for both cars.
Don’t let the Force be with you!
Friction is the enemy. The axles that come with AWANA cars look smooth, but they can be improved. By using a variety of sandpaper, we were able to take away the roughness of the axles; we wet sanded with 800, 1000, 1500, 2000, 3000, 4000, and 5000 grit sandpaper.
The axles were chucked into a drill press, and the axles were sanded at 2200 rpm.
After sanding, they were polished with Brasso metal polish, followed by waxing with Johnson paste wax to protect the axles from rusting.
The result is demonstrated in this photo of unprocessed (top) vs sanded and polished (bottom):
By wet sanding and polishing, you will greatly reduce the friction on your wheels, and your chances of winning races will be improved.
STAY TUNED FOR MORE!