Initial Design and Specifications


YOLETTE'S COMPONENTS:

Each Yolette will be comprised of six different parts: a core, a faceplate numerical insert, a roulette ball, a clear cover, an acorn nut and a retainer ring. The core, faceplate and retainer ring will be injection molded out of polypropylene, the clear cover will be thermoformed and the roulette ball and acorn nut will be bought from McMaster. The yoyo will be held together via the traditional 10-24 setscrew, spacer and nut assembly as described in lab.



Core: The core will be manufactured via a traditional, two part mold process. We will locate the ejector pins in the surface that is buried underneath the numerical insert faceplate to improve the appearance. We will be injection molding the part using a brown coloring for the resin but have been researching options to paint the yoyo and give it a mahogany finish. Before initiating each injection cycle a nut will be placed inside each core, within the structure that keeps the acorn nut in place (center of the roulette wheel) via the screw and nut method but will ensure a cavity through the whole part by pressing against the cavity mold. This is a very important step in our manufacturing process as it will provide us with a way to assemble the yoyo together and will ensure a location for the acorn nut which plays a key role in creating a roulette within the yoyo’s face.


Faceplate: The faceplate or numerical insert will be comprised of the gray/gold plate and the black and red slots. This is a two part process, where we will employ two different sets of molds, one to create the slots, one black and one red for each face of the yoyo and another mold that assembles the two slot sets and allows for the injection molding of the gray/gold area. The slot mold will have an outer ring that constitutes the runner and allows for the placement of the slots in the faceplate mold. This process was described in lab and we are very interested in applying it to our design. We believe that if successful, it will reduce the time required to assemble each individual yoyo when compared to options such as laser cutting the individual slots or coloring them in.


Retainer Ring: The retainer ring snap fits on the core of the yoyo, lamping the thermoformed clear cover in place. The design follows the instructions stipulated in lab for the snap fits including the one sided tolerances on mold manufacturing for the internal and external diameter features and the length of engagement of 0.150”.


Clear cover: The clear cover will be thermoformed out of clear 0.030” high impact polystyrene and will have a donut shape with a perforation in the center so that the setscrew can go through and screw into the acorn nut. Due to the draping methodology employed in its manufacturing we will need to focus our attention into the locations of the vacuum perforations and control the stresses on the sheet of polystyrene. The cover will be held in place by the retainer ring and will serve the purpose of holding the ball inside the body part.


Acorn Nut: Click here to see details of the acorn nut in the McMaster website. 
Roulette Ball: Click here to see details of the roulette ball in the McMaster website. 

TABLE OF SPECIFICATIONS: 


GANTT CHART:

Click here to see the detailed schedule with the timeline and description of each major task.

Posted by: David D'Achiardi and Jose M. Linares


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