Post #4: Final Design Concept

We finished a final concept for roundabout design which is introduced in the next couple figures below from different perspectives in SolidWorks.

Figure 1: A top view of our design.

From the top view in figure 1, handrails are attached to the top of the rotating platform as a safety measure for people to hold onto while spinning, and as points of contact to push on.

Figure 2: A side view of our design.

The gap between the rotating platform and the static base is due to 4 wooden blocks, and the generator is put in the gap as well. There is a fixed shaft that starts from the static base and goes through the rotating platform. The top part of the shaft has an external casing that is connected to the handrails and will be able to rotate with the top platform. Ideally, there would be covering preventing the gap from being so accessible but we will not be putting one on this prototype due to expected resource constraints.

Figure 3: A stripped, bottom view of the design.

From these bottom views in figures 3 and 4, you can see that the blocks are connected to the rotating turntable and the static base, meaning it does not prevent the top platform from rotating (one part of the ring rotates and the other is static).

Figure 4: A bottom view of the rotating platform.

We plan on having a larger gear attached to the rotating platform in contact with a smaller gear that is attached to the generator shaft, which would give us a higher RPM on the generator shaft than the RPM of the roundabout itself. We decided we want helical gears based on the design analysis table in table 1 below.

Table 1: Design analysis table for spur vs helical gears.

In this table, a higher number is better, so the helical gears won 3/4 categories. However, we may have to settle for spur gears if the manufacturing costs of the helical gears end up being too high, but we are in the process of talking to a manufacturer for a quote.

Figure 5 below shows a stress analysis done on the model in SolidWorks.

Figure 5: SolidWorks stress analysis of the roundabout.

The purple arrows in this image represent a force of 400lbs being pushed on the rotating platform, and the majority of the platform experience green levels of stress, meaning our roundabout should not be at threat of failing due to stress and can support our target weight limit.

To prepare for the execution in the spring of 2021, we have reached out to the machinist to talk about his capabilities and our design, and we have contacted gear companies to see if they would be willing to provide for us. We also plan on ordering some of our parts over winter break, such as the generator and platforms, so we can be prepared to start building as soon as possible in the spring. The challenges we anticipate would be Covid-19 slowing down shipping and manufacturer activity, as well as the special welding type needing for welding aluminum (our preferred handrail material), so we might have to change our handrail metal.