The last month or so has been a busy time with my youngest in the workshop. She had decided to do a science fair project comparing different bearing types (mainly because she wants to build a go-cart in the spring)
Her project design was pretty simple, build a bunch of identical cars with different bearing materials, and run them down a course with different weights and see which performed the best.
The cars were built with no bearings, nylon bearings, bronze bearings, and ball bearings. They ran without weights, and with 3 lbs and 5 lbs on them. It was a fun little project, and I am proud of the time and effort she put into the research and the building.
Hopefully she will get a ribbon by the end of January 2015!
The cars are identical, built of 1/2 ply, with 3 inch polyurethane wheels ($.50 each from surplus center). They have a 1/4" steel rod for the axle, that took a LOT of polishing to get smooth enough to use, and a dowel for the weights.
The track was 1/2" MDF, that was raised high at one end, and just a little at the other end to keep the cars at a reasonable speed when they hit the stop. The track was 24 feet long, and took up the entire hallway.
The cars were timed by a simple computer stopwatch program. On one end of the ramp, the cars pushed the 'F2' button on a keyboard, and on the stop line it pushed the 'F3' button on another keyboard. It worked surprisingly well. The secret was to make sure there was a fixed stop so the cars didn't destroy the keyboard on the finish line!
A link to one of the trial runs is below. https://www.youtube.com/watch?v=jtge...ature=youtu.be https://www.youtube.com/watch?v=eJeX...NhDl378WuwA7rQ
The woodworking was pretty simple, using jigs to make sure all parts were cut the same, drilled the same and assembled the same. A router and some rubber bands were the key to the timer start mechanism, and a hinge and a dowel were the key to the finish line. My daughter did the lion share of the work, except for the router and the tablesaw which scare her to death. <<< she loves the air nailer, drill press and chop saw, though! >>>
Sorry about the mess in the shop pictures!