Design Updates

After the design review, we've made updates to our yoyo conceptual design. Our updates reflect two major issues that were identified during the review:

1. The thermoformed glass part could slip off backwards toward the axle, and getting a consistent press-fit with the inner liquid component would be difficult.
2. The lime as it was previously designed would be difficult if not impossible to injection mold and the press-fit pins holding the two halves together would be likely to break or not align properly.

To address the first issue, we decided to secure the glass at the base, near the axle, to ensure that it would not slip off in either direction. Since we would no longer need a press-fit near the top of the glass, we returned to a conical glass shape. We brainstormed glass attachment methods, some of which are shown below.

Brainstorming ideas for securing the glass to the yoyo body

We decided that designs that rely on a metal spacer to separate the two halves were the most likely to work. Concepts 1 and 3 were CAD'ed for further analysis.

Concept 1: Single Spacer

Concept 2: Double Spacer

The first concept uses a single metal spacer to separate the two halves to both constrain the glass to the yoyo body and maintain the correct string gap of 0.075". The spacer also serves as the axle. Unlike the traditional yoyo design, the spacer is 3/8" in diameter and sandwiches the plastic of the yoyo body in between the nut and the spacer, rather than contacting the nut directly. We anticipate this may cause some deformation of the plastic which could affect our string gap tolerance.

The second concept uses two metal spacers. The inner spacer (orange) contacts the metal nuts on either side, while the smaller, thinner spacer (blue) constrains the glass. This design would allow tighter tolerances since it involves metal-on-metal contact to maintain the correct spacing, but would likely require purchasing or manufacturing spacers of custom dimensions.

The lime was redesigned to be more robust. The two halves come together along the center plane of the lime and are press-fit together. The lime is designed to press fit onto the glass edge and be removed during usage. Further design work will be needed to finalize the press-fit and mold geometry.

Lime on glass

Lime cross section

With our design nearly finalized, our next steps are to start making molds and conduct test runs of our manufacturing process to determine any pain points going forward.

Design Review and CAD!

After narrowing down to three ideas, our team decided to move forward with...

... the Cocktail Yoyo!

The idea: A transparent glass with a colorful drink, garnished with a lime. 

With this inspiration in mind, we arrived at the following design:

And now a bit about how it works! We broke up our design into four main parts, which we call the glass, the liquid, the ice, and the lime.



the glass

The glass is the body of our yoyo. It will be thermoformed with clear plastic to create the glass-like outer shell that we are after. The glass will close-fit over the set screw and press fit with the liquid dome inside.


the liquid

The liquid is the drink itself. It will be injection molded and will have several important connections. The liquid will press fit into the glass, and the ice will then be press fit into the liquid.


the ice

The ice is a cover for our yoyo. Like the liquid, this part will also be injection molded. The ice will be press fit into the liquid.


the lime

                                                                                

Without the lime, our cocktail would be incomplete. The lime garnish is an injection molded part that has two pins. These pins will connect the halves of the lime around the rim of the glass.