For a broader list of project tips, see the Lessons Learned page on the 2014 projects wiki.

Final Result

The final product did not transport marbles as reliably as expected. This is due to the difficulty of getting a fast-moving linkage to touch two specific small points that are attached to the ground. The mechanical design was quite robust; the only potential area for improvement was the teeth of the spur gear, which were the first point of failure of the mechanism. The bearing joint design, while unnecessarily complicated, did not cause any issues and performed perfectly.

Specific Future Improvements

Position Flexibility

The ability to tweak positioning of crucial components would make the system design more robust. Using slots instead of holes is an easy way to allow for repositioning. We employed this method with success on the claw mechanism, but for the input and output platforms, a design overhaul would be needed. Replacing the wooden base with a frame of (for example) aluminum T-slot extrusion would allow the platform positions to be tweaked quickly and easily while still maintaining a stiff ground link.

Motor Speed

The 1:131 gearmotor could not run at low speeds in either direction. It is unknown whether this was a limitation of the gearbox design (internal friction), or if the gearmotor was damaged. Either way, adding a basic drivetrain with a single belt and two wheels would allow the device to run at lower speeds than shown in the YouTube video. This would improve system reliability and safety, since the tower itself is large and the spinning motion could be potentially dangerous, either for onlookers or the device itself.

Appearance

A number of additional components could be added to the device to make it flashier and more polished. For example, it would be trivial to add LEDs to the base that would illuminate the device, and change the color of the LEDs based on the analog signal from the potentiometer. In this way, different speeds could be represented by different colors (i.e. green for fast, yellow for slow, and red for stop).