I designed and mass manufactured over 80 of these Game of Life themed yo-yo's with a team of five other students as a part of MIT's course 2.008 Design and Manufacturing II.
We followed a full design and mass manufacturing processes for these yo-yo's:
Design pitching and review
Creating a manufacturing plan
3D modeling all parts of our yo-yo
Creating metal molds of each part of the yo-yo using CAM and HAAS CNC mill
Injection molding parts
3D printing molds for thermoforming
Printing sheets for thermoforming with Mimaki
Thermoforming the spinner
Presenting progress to professor and TAs
The cap is the top part of our yo-yo which is 1/2 of the press fit holding the yo-yo together with the base. The cap is green and wavy as reference to the holder of the spinner in the board game. I completed the CAM and HASS CNC mill manufacturing for the core side of the mold for our yo-yo cap.
The cap of our yo-yo
My CAM for the core side of our mold for the cap
Final molds after using HAAS CNC mill. The right mold is the core mold I manufactured on the HAAS CNC mill using my CAM.
Me HASS CNC mill manufacturing the core mold for the cap
The finger ring was an element of uniqueness that we wanted to add to our yo-yo. The string of the yo-yo would be tied to the finger ring and the guest would put their finger into the ring to use the yo-yo. Another great feature of the finger ring was that the finger ring also fit perfectly on the middle of the spinner for easy storage when the yo-yo is not in use. We created both blue and pink finger rings as reference to the blue and pink people in the board game.
I manufactured the finger ring mold in the HAAS CNC mill. After the finger ring mold was complete, I filed the gate by hand to get the gate as small as possible to create the highest quality parts and minimize defects. After the finger rings were injection molded, I drilled holes in the finger rings for the string of the yo-yo to tie into. I also sanded the finger rings for guest comfort and to file away injection pin marks as much as possible for aesthetics.
The blue version of our finger ring
Me manufacturing the finger ring mold in the HAAS CNC mill
Final finger ring mold after I finished manufacturing using the HAAS CNC mill and filing the gate by hand to minimize defects
The spinner is my favorite part of our project. It is a colorful thermoformed piece which can actually spin! I worked on preparations for the thermoform mold, thermoforming, and testing.
Our spinner originally had 3D numbers and much of my early work was on trying to make 3D numbers work. Ultimately, the 3D numbers were too difficult to align with the colored print of the thermoforming sheets. Therefore, we shifted away from the 3D numbers and opted instead for a more manageable but still beautiful flat number design where the numbers were just printed on the thermoformed sheet.
Our 3D model of the spinner mold
I created this first draft of the 3D ring of numbers for the spinner. I created the image in Illustrator then turned it into a 3D model in Fusion360 which was combined with the rest of the original spinner mold 3D model.
After finishing the 3D model of the spinner mold, we 3D printed the mold to use for thermoforming. I drilled air holes into the mold for better thermoforming results. I tested thermoforming with different heat, cool, and time settings to get the best results. I also tested thermoforming on different thermoforming materials including clear plastic and white plastic. We ultimately decided on white plastic as it was most similar in appearance to the original Game of Life spinner.
This thermoform highlighted imperfections of the air holes that were drilled into the mold and had warping from heat
This thermoform hid imperfections better but the numbers were not very clear
This thermoform hid imperfections and had clear numbers!
Early testing of spinning the thermoformed spinner on the base. Modifications were made later to improve spinning in the thermoforming and die cutting processes.
Throughout the process, I worked on quality testing our yo-yo to be sure it fit within our quality standards.
Strategies that we used to minimize defects in the manufacturing process
I measured our manufactured parts to be sure that the parts we were producing were within our design specification limits.
I performed drop tests in order to be sure that our press fit between the cap and base was strong and could hold up to regular yo-yo use. All of our final yo-yo's were able to sustain at least a 2 foot drop without the press fit coming apart.
I also performed spin tests for all of the thermoformed spinner parts to be sure that the spinners were spinning as freely as possible.
I completed the assembly process for many of the final yo-yo's. This included pressing the base, thermoformed spinner, and cap together. Two halves of the yo-yo were combined with a string, screw, and spacer. The finger ring was attached to the end of the string.
Final assembled yo-yo's
Final assembled yo-yo's with blue finger rings
Final assembled yo-yo's with pink finger rings