Initial Designs and Plans (BD#1)

Our team is incredibly excited to begin working on our yoyo. Below are some of our initial designs with manufacturing and design considerations included.

Screen Shots of the Assembly

Summary of the Process (with Applicable Design Principles)

We strategically chose colors and fitting methods to ensure ease of assembly. By limiting colors to black, red, white, and purple, we were able to group pieces together for the molds and reduce the amount of molds used. This also allows for an assembly process that was optimal in terms of time and cost. Each part's assembly and manufacturing process is explained below.

Inner Silhouttes

The heads and bodies of the Mad Hatter and Red Queen within the yoyo will be made using injection molding. This decision was made largely due to the complex geometries of the heads and the volume needed for the yoyos. Due to the different colors of the different elements of these silhouettes, we decided to have them be fit together using either snap fitting or press fitting. This means that we will have to add posts to the back of certain elements. By snap fitting or press fitting the elements, we can make molds separate from the elements based on color and remove the difficulty in terms of cost and time of trying to link them together using injection molding. Regarding assembly, the fixed aspects of the body and heads will fit into the spacer also using snap or press fitting.

Base and Spacer

The yo-yo base will be manufactured using injection molding due to the complex geometry and large volume of yo-yo’s being made. The base’s symmetric design minimizes the amount of molds required to construct a complete yo-yo. The butterfly styled bases will be connected by a yo-yo axle and nut that will be installed into the yo-yo base mold before every injection molding cycle. In order to maintain a flat surface for the rest of our design, an injection molded spacer will be press-fitted onto the extruding boss of the base and held rotationally in placed by a pin.

Pin

A 1/16” metal pin will be used to hold the spacer fixed onto the base and to provide a rotational joint for the heads of our design. The pin will be press-fitted onto both the spacer and base. The head pieces will be able to fit loosely enough to allow rotation. The head pieces will be constrained in the axial direction of the yo-yo by the thermoformed clear window.

Snap Ring

The snap ring will be made using injection molding, as the geometry and thicknesses of the part make it more amenable to injection molding than thermoforming. The lettering on the snap ring will be part of the mold, which was a consideration when we decided whether to make the letters raised or engraved on the surface of the ring. We preferred not to mill the letters, as that would take much more time than incorporating them into the mold, and raised letters tend to be better defined than engraving when using injection molding. The snap ring will be snap fit onto the yo-yo base on top of the window, effectively holding the window and the rest of the inner assembly in place.

Window

The window would be made by thermoforming clear plastic to ensure visibility of the parts within the yoyo. The process was also chosen since the window does not require any intricate designs to be manufactured like other components in the yo-yo since it comprises of a thin part and has a simple shape. The window would be placed within the groove in the yo-yo base, and would be held down by the snap-ring.

Specifications for Yo-Yo Design

Gantt Chart (click here)