Praxis reflection- Rube Goldberg

Making the Rube Goldberg machine, I experienced how the construction of knowledge in the head happens best when constructing tangible objects and share in the world (Cole & Wertsch, 1996). The creation of an artifact allows me to externalize and iterate on my thinking throughout the making process. For example, when I was thinking about the functions that I could create from a Gogo board’s motor, I needed to externalize my idea through sketching (Figure 1 & 2). I came up with ideas like making a fan that would blow a ping pong ball to another direction; a pulley that would drag a basket of a ping pong ball up and down. I made a small prototype (Figure 3) to test out my idea. Turned out that making a fan wasn’t working well, so I moved on to the new design.


Figure 1&2: A sketch of what can I do with a Gogo Board’s motor

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Figure 3: A quick prototype of a fan.
Figure 4: Pegboard inspiration from Pinterest

Engaging in a constructionist learning environment, I took an active role in my own learning by designing, building, and exploring my project ideas (Ackermann, 2001). I looked for inspiration for the new design on Youtube and Pinterest (Figure 4) and found that pegboard is a good and manageable start for a Rube Goldberg machine. I tinkered with materials, repurposing tools, and problem-solving design challenges. For instance, I started by measuring the diameter of the dowel (that I would cut out as pegs) and it was 0.25 cm. Then I printed out a circle with 0.25 cm diameter on plywood and found that the circle was too loose for the dowel to fit. I tinkered with different sizes by printing out multiple circles with the diameters of 0.24, 0.23, and 0.22; 0.23 was a perfect fit for the dowel peg. After that, I made more copies of the 0.23 circles and aligned them on illustrator to create a pegboard design. Being at the lab, Jonathan, Monica, and Yipu helped me with the woodshop tools, which I learned how to use these machines for the first time (Figure 5). This reflects Vygotsky’s work on the Zone of Proximal Development as it emphasized the level of which I am capable when working alone and the level that I’m capable of reaching with the help of an expert (Cole & Wertsch, 1996).

Figure 5: Me, working on the woodshop tools like a noob

Working toward the design of the Rube Goldberg machine, I experimented with different ways to design the layout and make the marble falls into places. At first, I made a sharp slide down which made the marble fell off the pegboard (Figure 5). Thus, I needed to redesign the layout so that it fell to each ramp smoothly. After a series of rolling marbles down the slopes, I learned to make my ramp less tilted and used small pieces of plywood so that the marble wouldn’t fell off the ramps. I contacted Melissa (the previous -stage group) and she said that she would splash water to trigger the rain sensor. I used a servo motor to start the marble rolling down on to the ramps. Once Melissa’s team splash the water to me, the marble will start rolling. I often met Elliot and Qi at the lab and we discussed different sensors that we would use as a transition. We ended up with a light sensor. To end that, the marble runs down the ramp and stops on top of the proximity sensor. The proximity sensor triggers a motor that is attached to a string. The string pulls up a small box. The box exposes the light sensor for the Elliot and Qi’s machine (Figure 7).

Figure 6: My first layout for the ramps
Figure7: The Design- 2/11
With my teammate

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