Introducing the Space Yo-Yo®

It's out of this world

Coming to a planet by you December 2013

The Space Yo-Yo® is a revolutionary yo-yo designed from the ground

up to bring the feel of space travel straight to your hand. Incorporating

 the manufacturing and design skills of the 2.008 Lab Group D3, the

Space Yo-Yo® will make you feel as if you were on the moon. Today's blog

post will go over a quick summary over how the parts of the Space Yo-Yo®

will be manufactured and assembled.

The Space Yo-Yo is composed of two identical halves. Each half is

composed of 6 parts: the Body, the Moon and Stars, the Night Sky,  the Rocket,

the Window, and the Ring. Each half of the Space Yo-Yo® is connected

by a 10-24 bolt that screws into machine nuts embedded in the Body of the

Space Yo-Yo®

 The half assembly of the Space Yo-Yo® 

The Body of the Space Yo-Yo® is to be injection molded by the injection molding 

machine located at MIT's Laboratory for Manufacturing and Productivity. The thickness 

of the Body ranges from .2" to .25" to allow for easier flow of injected plastic. 

The outer surface of the body is angled outwards for easier removal from the mold cavity. 

The inner hole of the Body is designed to hold the the Moon and Stars, the Night Sky,  

the Rocket, and the Window. With the Ring snap fit in to secure them in place. 

The Body of the Space Yo-Yo®

The Moon and Stars of the Space Yo-Yo® is thermoformed plastic designed to resemble 

a shooting star over the moon. The Moon and Stars is designed so that the raised regions

are not tightly grouped for easier thermoforming. 

The Moon and Stars of the Space Yo-Yo®

The Night Sky of the Space Yo-Yo® is to be injection molded by the injection molding 

machine located at MIT's Laboratory for Manufacturing and Productivity. The Night Sky is 

designed to fit over the Moon and Stars to create the illusion of being in space. The Night Sky 

has a constant thickness which allows for easier plastic flow during injection molding.

The Night Sky of the Space Yo-Yo®

The Rocket is of the Space Yo-Yo® is to be injection molded by the injection molding 

machine located at MIT's Laboratory for Manufacturing and Productivity. It is designed

to resemble a rocket flying through space. The rocket has a constant thickness 

which allows for easier plastic flow during injection molding.

The Rocket of the Space Yo-Yo®

The Window of the Space Yo-Yo® is a thermoformed designed to allow a clear view of 

all the parts under while creating a smooth surface on the top of the Space Yo-Yo®. The 

window has a single raised feature with no fine details for easy thermoforming. 

The Window of the Space Yo-Yo®

The Ring of the Space Yo-Yo® is  is to be injection molded by the injection molding 

machine located at MIT's Laboratory for Manufacturing and Productivity. It is a simple 

round ring with a constant thickness making injection molding easy. It is designed to snap 

fit into the Body to hold all of the parts together. 

The Ring of the Space Yo-Yo®

We made a set of specifications for our yo yo. Ideally, each of the finished assemblies should be within the listed tolerances. We will measure the parameters that we can once production begins and analyze how well our processes were controlled.

	Target	Tolerance	Meaurement Device
Complete assembly
Diameter	2.500"	+/- 0.005"	Digital Calipers
Total Width	1.575"	+/- 0.005"	Digital Calipers
String gap	0.075"	+/- 0.005"	Digital Calipers
Mass	84.00g	+/- 5.000 g	Scale
Max rotation speed	5100 rpm†	+ 1000 rpm/- 500 rpm	Laser tachometer
Moment of inertia (Izz)	0.1474 lbs*in^2	--	--
Balance
-- Center of mass (x)	-0.0105"	+/- 0.005"	--
-- Center of mass (y)	0.0054"	+/- 0.005"	--
Height of oscillations	0.0118"	+/- 0.005"	--
Total string clearance	0.025"	+/- 0.010"	Digital Calipers
Part 1: Body of yo-yo
Inner diameter	1.988"	+ 0.000"/-0.005"	Digital Calipers
Engagement length	0.215"	+/- 0.005"	Digital Calipers
Part 2: Ring
Outer diameter	2.000"	+ 0.005"/-0.000"	Digital Calipers
Thickness of outer diameter (engagement length)	0.215"	+/- 0.005"	Digital Calipers
†dropped from a height of 30" (no throw)

Many of our specs come directly from our SolidWorks model. The program has built in tools to calculate mass properties, such as moment of inertia and center of mass. Calculating rotation speed and oscillation height took a bit of 2.003 magic, which is really the just the application of the laws of motion.

If we hope to get close to the targets, we need to compensate for shrinkage in the injection molded parts. We estimated our correction factors by measuring parts and the molds they came from made in previous years with similar geometry.



We've also created a Gantt chart to keep track of all major tasks and deliverables. Who is responsible for what components may change over the course of the semester, but right now it has been divided up as follows:
For part/mold design:
Body - Matt, Rachel
Moon and Stars: Nelson, Camille
Ring, Window, Rocket: Oscar, Emily

For manufacturing:
Body: Matt, Rachel
Moon and stars insert: Nelson, Camille
Thermoform parts: Nelson, Rachel
Ring, Rocket: Emily, Oscar

To view the full version of the Gantt Chart:
https://docs.google.com/file/d/0B-OZv6MPFiExT2JhdlFrdmJoV28/edit?usp=drive_web