Early Design
Design Ideation
For our team brainstorm, we first identified common areas of interest: beach, space, foods (personified food!), and animals. We also thought about cool mechanisms we could include in our yo-yo. Within the yo-yo design constraints and requirements (# of parts needed, processes used for parts), we chose our three favorite yo-yo concepts that each had plenty of room to explore:
Lifesaver Yo-yo:
We came to this idea because we wanted to do something cute like personified animals or foods. Some ideas were thrown around - bao in a hot tub, cat in a tea cup. We came across a Uniqlo shirt graphic of a Gudetama floating aimlessly in a lifesaver ring and thought the concept of designing a character (maybe Gudetama, maybe not) floating in a lifesaver and making asymmetric yo-yo halves would be a fun direction to take our semester design.
Solar System Yo-Yo:
We came to this idea because we wanted to do something out of this world (jaja get it?). None of us study aerospace engineering, but we figured the deepest depths of space was the future of mankind. Instead of looking down and worrying about our place on the dirt, we should look up at the sky and wonder about the stars. Mankind was born on Earth, but it was never meant to die here. Hence, we decided to help humanity out and muster up this space design to commemorate the greatest solar system in this galaxy.
There will be a large spherical sun thermoformed in the center of our yo-yo. Surrounding the sun in the center will be a couple of injection molded planets of varying sizes and colors (not Pluto because Pluto is no longer a planet). A spherical clear casing will snap fit and surround the planets and sun. The design will be symmetric about both halves.
EGGIE: Initial Design
We voted on our favorite designs, and we all chose the Lifesaver Yo-Yo with Gudetama concept. We feel that the egg will be very relatable to our fellow college students and we will definitely enjoy looking at his cute little face all semester long. We named our team EGGIE, which is Korean for "baby" and fits perfectly for the little egg!
We thought carefully about how we can best design the parts for manufacturability and assembly, while keeping aesthetics, quality, and functionality in mind. Here's a picture of our initial CAD model, next to our concept drawing:
Our design has seven unique parts, five of which are injection molded and two are thermoformed. Our exploded assembly view has the parts annotated below.
Arms (injection molded) x2 press-fit into the water top
Floatie top (injection molded) x16
Floatie base (injection molded) x2
Water top (injection molded) x1
Egg top (thermoformed) x1
Egg bottom (thermoformed) x1
Water bottom (injection molded) x2
Some key considerations that went into our design:
We decided to make the floatie top pieces separate from the floatie base so that they could act as "clamps" to sandwich all the interior pieces (water and egg). However, based on how the manufacturing of these tiny interference parts go, we may choose to use overmolding instead to get the colored stripes.
Since the egg top and bottom will make the yo-yo asymmetrical, we are wary of the yo-yo not "yo-yo-ing" properly if the weight is imbalanced. For now, we chose to thermoform the egg parts so that the thin plastic choice will hopefully make the asymmetry trivial. If this asymmetry proves to be non-trivial, we may embed washers on the lighter side (likely the bottom) to offset the imbalance.
The egg's arms are also press-fit into the water top. We did them separately from the egg top for several reasons: thermoforming the egg top with extending arms would be impossible due to the large undercuts, and having the arms come out of the water add to the aesthetics of the egg, struggling to hang onto the floatie.
Since our design already has so many parts, we decided to forego making tiny eyes and mouth for the egg face. Instead, the thermoformed egg top will have small protruding features that we will paint black and white.
We 3D printed our design to see how it looks and feels in the hand. We realize that we want the egg's bottom and legs to be thicker for manufacturability and aesthetics:
We worked very hard on communicating all our details in our Design Review slides, and we're excited to present in class this week and get feedback. Check them out here!
