Sunday, March 13, 2016

Deliverable 1: Yo-Yo Design


The theme of yo-yo is based around MIT's hacking culture. One face of the yo-yo will be the famous MIT dome with a ring of famous hacks rotating around it. The other face will feature a hacker's map. There are only two unique thermoformed components that are relatively simple. The other four parts of the yo-yo are injection molded. Of these, there are three unique molds. A bearing will be added to the dome face for the rotating hack disc. A counter weight in the form of a shim will be placed on the opposite face to counterbalance the weight of the bearing. The two main bodies of the yo-yo will be screwed together with a set screw. Each face will have snap fit components. The dome piece and hackers map will both snap fit into the main body. A final clear cover will go on top of the dome and will allow for the snap fit.

Dome Face

Hacker's Map Face
Full Assembly. From left to right: clear thermoformed dome cover, dome face, hack ring, bearing, yo-yo body, set screw, second yo-yo body, weighting shim, hacker's map face.

Principles of Design for Manufacturing:

1. Aluminum for the Molds: The molds will be made out of aluminum which is a softer material. This will allow for easier manufacturing of the molds. This is also a much cheaper material than steel.

2. Repetition of Molds: For ease of manufacturing, the core molds for the distinct faces of the yo-yo are designed to be the same while only the cavity molds will be different. The actual body for both halves of the yo-yo will have the same mold to reduce the number of distinct molds that must be created.

3. Simple Thermoform Designs: To reduce complexity and cost, there are only two thermoformed parts that are very simple. One is a clear cover for the dome face while the other is a thin disc that will have hacks on it.

4. Two Part Body: The yo-yo was designed to have to main body pieces rather than one piece. This reduces the risk of having a piece that is too thick and it saves material and time. Efficiency is key to manufacturing, so if the yo-yo were to be one piece the cooling time would be very long and the chances of defects and warping would increase significantly.

5. Easy to Assemble: The entire yo-yo will assemble very easy since majority of it is snap fitted together. Both faces of the yo-yo will snap fit into the two body pieces and an additional clear snap fit cover will be on the dome face side. This will allow for quick and cost effective assembly since no additional joining or bonding materials will be needed.

6. Cost Effective: A bearing is required in the design to allow the ring of hacks to rotate. Due to high costs of bearings, only one will be used. To counter balance the weight, a much cheaper shim will be placed on the other side. Further, to reduce complexity and cost, the hack ring will have stickers as the hacks rather than small and intricate thermofored or injection molded parts.

Table of Specifications:

Critical Dimensions
Target Value
Expected Tolerances
How will we measure?
Total Mass
Using a scale
Max Rotational Velocity
106.3 rad/s
+/-.005 rad/s
String Gap
Dome Injection Mold Thickness
Dome Thermoform Snapfit ID
Hacker’s Map Injection Mold Thickness
Hacker’s Map Thermoform Snapfit ID
Hacking Ring Injection Mold Thickness
Clear Thermoform Cover Snapfit ID
Shell Dome Injection Mold Thickness (Thinnest)
Shell Dome Injection Mold Thickness (Thickest)
Shell Dome Thermoform Snapfit OD

Assumptions for rotational velocity calculations:
Max rotational velocity right before it stops and at its max string length
String length: 30in = 0.762m
Mass= .63lbs = 0.29 kg
J = 0.5*m*R2 = 4.07 E-6 where R=0.0053m using the solid cylinder formula for moment of inertia

V= 3.54 m/s = 106.3 rad/s

Gantt Chart

Link to google gantt chart.

Majority of the SolidWorks portion of the yo-yo ,especially for injection molding, will be handled by Ryan and Elizabeth. The thermoforming tasks will be handled by Danielle. The Mastercam work for machining all the molds will be done by Sabrine and Silvia. The taks regarding optimization, assembly, and actual machining will be done by everyone. Further, for deliverables, the blogs will mainly be handled by Sabrine and Silvia while the paper deliverables will be dived evenly among everyone. 

Sunday, March 6, 2016


Welcome to the Hack Yo Dome page! We are a team of five students at MIT taking the 2.008 Manufacturing and Design II class. This semester, we will be working together to create a unique yo-yo centered around MIT's hacking culture. Our yo-yo will feature the MIT dome with a disk of several hacks rotating about the dome. The yo-yo will not only feature classic historical hacks, but it will also have a hackers map on the opposite face. The team is comprised of Sophomore Ryan Gulland, Juniors Danielle Barillas, Elizabeth Glista, and Sabrine Ahmed Iqbal, as well as Senior Silvia Vazquez. We are excited to go forth and "Hack Yo Dome"!
The team in front of our main inspiration, the MIT Dome!