Marble Maze Recirculation

Automated systems are everywhere and are possibly the most important innovation in manufacturing. For this project, we were tasked with designing a machine to circulate ball bearings through a system of marble maze panels as quickly and accurately as possible.

Our learning goals for this project were to be able to work in a larger group than usual (5 people) and learn how to manage a team of this size.

The Build

For this project, we began by each tackling a separate component of the machine. The five tasks were:

1. Rework existing panels to function consistently
2. Get the belt running and adding a pulse width modulator to control speed
3. Design and build a catcher for the balls at the top
4. Design and build a catch and release mechanism at the bottom
5. Design and 3D print a part to attach to the belt to deliver balls from top to bottom

I was tasked with all CAD/CAM work on SolidWorks, which included the design of a lifter device and the design of a catch/release at the bottom that would work hand in hand to smoothly transfer balls from stationary at the bottom of the machine to the top of the maze to recirculate through.

First I began by attempting to make a rough prototype out of cardboard, Kraft sticks, and any other available materials to give myself an idea of what to design. I came up with the idea of a small box like device with two prongs sticking out to grab the ball out of a similar but wider pronged release mechanism.

With these concepts figured out, I began designing first the release mechanism on SolidWorks. Along with the design I had originally thought out, I put an emphasis on giving the machine the best chance at working every time by creating a component that would allow for a greater margin of error, given that the belt wobbled side to side a bit. Below is a picture of the "launcher" in its final version.

Details of imp

The next component was the lifter device. This was the more difficult of the two components to design, because it needed to be both small and strong enough to withstand some wear and tear from the speed of the belt and hitting the release mechanism. The goal was to design a small device that could be mass produced and easily clipped onto the belt to have a continuous stream of balls moving through the machine.

Results

As can be seen in the final testing video at the top of this page, our marble re-circulation machine met and exceeded expectations. Our group was able to consistently circulate more than twice as many balls as any other group given the 10 ball limit and 60 second trial. We were able to circulate 32 balls in this time frame, a rate of about a ball every 2 seconds. These numbers were measured by counting how many balls passed a certain point in the maze (marked by the red line, which is visible in the video). Along with the video of the full machine working, here is a close up of the bottom section where the balls were delivered from launcher to lifter.

Conclusion

Overall, this was a very successful project. We learned how to work as a team and manage a large team while performing at a high level skill-wise. It was a very engaging project that allowed for the use of many different fabrication and design skills, as well as problem solving. The concept of automation and autonomy of machines is one that has always interested me so this project was really interesting.

Two informal lessons I learned were over-prepare for things to go wrong and think through designs in every possible way before fabrication.

If I started over from the beginning, there is not much I would do differently. My design of the launcher and lifter worked almost perfectly. The only small adjustment I would make would be to be more conscious of the strength of PLA. This means designing thicker pieces with more supports where necessary. Specifically, don't make 1/8" diameter rods with no support.

Lastly, the only change I would make to the project would be in testing the machines, the ball limit should be more flexible because for our machine we realized once it was fine tuned that our main limitation was only being able to use 10 balls. Since balls took longer to go down the maze than up the belt, there would be long breaks where balls were circulating in the maze but lifters were going up and down with no payload. We could have easily handled around 15 balls, and been able to really push the limits of the task.