Sunday, October 6, 2013

SpaceJam Yoyo Design


 As was seen in our last post, our yoyo design is finished. Both sides of the yoyo feature the same lovely design of Bugs Bunny in the Air Jordans logo, surrounded by the Looney Tunes rings.
A beautiful render of our yoyo

The general shape of our yoyo is a butterfly design, which we thought was a better design for a yoyo because it helps to guide the string into the groove and runs smoother. Also, you can do more tricks with a butterfly design.


Our yoyo design features 7 different parts:
  • Red Ring: Injection molded part, will snap inside the orange ring.
  • Orange Ring: Injection molded part, will snap inside the red body
  • Clear Basketball Cover: Thermal formed part, will sit flush inside the rings and with the top face of the body
  • Black Bugs Bunny Insert: Injection molded part, will sit underneath the basketball cover
  • White Disk Insert: Thermal formed plastic, die cut into a circle
  • Metal Ring: Stock steel metal ring, used to weight down the yoyo
  • Red Body: Injection molded part, will house all the other parts inside the yoyo
Once these parts are all manufactured, the injection molded parts will need to have the runners cut off, the thermal formed parts will need to be cut down using a die, and the strings will need to be cut down for the yoyos.

The assembly of the yoyo can be seen in this exploded view of the drawing.
The metal ring will be snapped inside the red body of the yoyo. The white disk insert and the Bugs Bunny insert will then be placed on top of the metal ring. The basketball cover will be placed on top of the Bugs Bunny insert, and then the two rings will be snapped in place on top of the cover. Once each half of the yoyo is assembled, the strings will need to be tied around the shafts and the two halves of the yoyos will need to be screwed together.

During the design of our components, we took into consideration the manufacturing process.

When we were designing the components, we made sure to not exceed the maximum volume of 2.70 in^3. We also made sure that the thickness of the body was more or less uniform thickness throughout the part to allow for a good finish of the plastic.

While designing the Bugs Bunny insert, we made sure to design the curve such that the smallest end mill would be able to be used to manufacture the mold for the part. The design was also made such that the center of mass would be approximately still in the center of the yoyo. Additionally, we made sure to make the Bugs Bunny insert 1/16" thick, to prevent warping of the plastic that occurs due to the large sections of the disk like we saw on some other yoyo parts.

Example of warping on plastic disks

For the fits on the plastic rings and parts that need to press fit into the yoyo, we made sure to follow the tolerances of +0.000"/-0.005"for ID features and +0.005"/-0.000" for OD features. We also tried to make sure that the length of engagement for the rings was about .150" deep.




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