Retainer ring: Design

The retaining ring was designed in order to provide a snap ring around the top of the yoyo and have an attractive design for the face. 

We iterated through several possible designs for shutoff gaps, from a galaxy themed border to a number of stars to radial geometric designs (Fig. 1). Eventually, based on tool capability considerations and the opinions of team members, we settled on the design circled in red below. 

Figure 1: Potential retainer border designs, with selected design circled in red

 The selected design for the border and the retainer was tweaked to allow for tool parameters and structural soundness. The final desired dimensions are shown in Figure 2. The outer edge was filleted with a 0.1" radius to soften the design edges and make the yoyo more comfortable to handle.

The retainer ring was designed to snap on around the rim of the body of the yoyo, and hold down the thermoformed window and a steel shim that would provide a border that could be seen through the shutoff design.

As seen in the figure above, there are a few little tabs along the inner border of the retainer ring. Since the desired shims with a 1.5" inner diameter were only available with an outer diameter of 2.25", the thermoformed windows were also cut to this size. Instead of making the entire retainer and body smaller, the tabs were added in the design of the retainer to constrain the shim and window and keep them from sliding around.