Call Me Maybe: 2.008 YoYo Design&Manufacturing: Overview of the Call Me Maybe Yo-Yo

Yo-Yo Design:

The vision of team Call Me Maybe is to design a working Yo-Yo based off of the aesthetic of an old-style rotatory phone – you can see the full assembly in Figure 1. The Yo-Yo will be comprised of four injection-molded parts (finger-stop, dial, retaining ring, base), one thermoformed part (number pad), and other hardware including a dowel pin, torsion spring, and bearing (see Figure 3). The bearing, dowel pin, and spring will be used to simulate the spinning dial on a real rotary phone. The parts will be assembled almost entirely using press fits. The retaining ring will press into the base to hold the number pad in place, the bearing will press into the underside of the dial, and the dowel pin will press into the bearing. The torsional spring will then be integrated on the dowel pin, with its two points of contact being on the underside of the dial and the inside of the base. Finally, the dowel pin will press into the base, completing the half assembly. The two halves will be connected using a set screw to complete the full assembly.

Figure 1: Yo-Yo Assembly

Figure 2: Exploded Yo-Yo Assembly Isometric

Figure 3: Exploded Yo-Yo with Labeled Parts

Design for Manufacturing Considerations:

The major considerations for our Yo-Yo were deciding how many and what parts to injection mold or thermoform. Eventually we settled on making the 2D shapes in our Yo-Yo out of thermoformed plastic and the dense 3D features from injection molded parts.

When designing using the thermoformed part and the injection molded parts we had to make sure to give each of our parts the correct sizing to allow for a nice interference fit between the parts. This is the most important design consideration – without these interference fits our Yo-Yo would not fit together. Examples of this though process can be seen in out retaining ring – this interference fit is used to hold the thermoformed part in the Yo-Yo. Similarly when designing the “Finger Stop” on the face of our Yo-Yo we needed to make sure that the interference fit was dimensioned correctly for the size of the small part.

Finally when designing parts we tried to use as many circular features as possible – this allows us to use the lathe to create the tooling for injection molding which will greatly reduce our time machining/fixing our molds.