2. Design Considerations

1. Introduction     3. Kinematics     4. Prototyping & Building     5. Results & Discussion

MATERIALS

To design this mechanism, I embraced the concept of bricolage, or designing and building with whatever materials are available. Before  considering any design ideas, I searched my house for materials that could be useful. I knew that I would need gears to produce an appropriate fan speed. I found two sets of gears in a manual lawnmower (Fig. 1), various gears in our Roomba (Fig. 2), and gears from an extra bike cassette. I also found PVC pipes, dowels, and scrap wood to build a linkage mechanism and supporting structure (Fig. 3). I knew I would need joints for gears and linkages to spin smoothly. I decided I could use nuts and bolts as revolute joints, although the movement would be less smooth than using shafts and bearings (Fig. 4). I did not have properly-sized shafts for gears. To solve this problem, I wrapped dowels in duct tape to fit them into lawnmower gears and used small nails for the Roomba gears. 

Figure 1: Two sets of gears with a ratio of 5:1 were removed from a manual lawnmower.

Figure 2: I neglected to take any photos of the Roomba while I was taking it apart or putting it back together. Instead, here is a video of my dog meeting the Roomba for the first time.

Figure 3: I have a large selection of PVC pipes and fittings from another project.

Figure 4: I experimented with making joints out of assorted nuts and bolts.

1. Introduction     3. Kinematics     4. Prototyping & Building     5. Results & Discussion