top of page

Injection Molded Yo-yo

ENGS 146: Computer Aided Mechanical Design

May 2018

Objectives: Design and Manufacture an injection molded yo-yo in Thayer School's Machine Shop.


  • Solidworks Mold Design

  • Injection Molding

  • CAM Tooling Setup and Machining

The Design.

The Project.

Early in ENGS 146 I was tasked with designing and manufacturing a yo-yo suitable for easy injection molding.  Considering the center of gravity, moment of inertia about each axis, and yo-yo performance I came up with the design at right. I created a mesh of 5 Fibonacci spirals curving clockwise, and 8 Fibonacci spirals curving counter-clockwise. When spun, the yo-yo's sections appear to "grow". Draft angles and thermal deformation conditions were applied throughout the design process.


I created a two part mold using SolidWorks' mold tools and incorporated ball bearings set into spherical pockets as alignment pins. I used HSMworks, a Solidworks CAM plug-in to create 3-D toolpaths, as shown in simulation at right. I used CNC Prototrak Mills to machine the mold halves. Finally, the mold was injected with ABS plastic using a Morgan Press Model G - 55T desktop injection molding press.


CAD Model

Manufactured Yoyo



Watch Now

Finished Product:

bottom of page