The time has come. Us in Team Tropical Escape has finished assembling our yo-yos and are ready to go on a tropical escape with all of our Bitcoin money. But, before reviewing the final product, below we'll discuss a couple of the pieces.

Snap ring- The snap ring fabrication was completed between last Friday, Dec. 7th and this Monday Dec. 10th. We did not encounter any of the difficulties with burning that had been occurring earlier the week before. To complete the fabrication as quick as possible, we utilized three shoulder bolts acting as shafts to allow us to place the bolt inside the snap ring.

Stockline line overmold- This piece was completed last Friday, Dec. 7th, and has a sleek, elegant look. While fabricating, we were tinkering with he shot size and pressure profile because short shots were occurring. However, we noticed that the orientation in which we placed the stock line into the overmolding core affected how the filling occurred. We experienced flashing and short shots because of this. Given that the stock line is not an even design, this can explain the discrepancies. Furthermore, we still continued experiencing flashing along the outer diameter of the are where this piece snaps in to the snap ring. This then would not allow the pieces to snap. 

We believe the flashing is primarily due to the core of the overmold being to deep or too wide. Yet, due to time constrains, we could not fix the issue. But, we solved it by using an exact knife to cut off the excess plastic, and this worked well.

'B' overmold- 'B' overmoding was completed on Monday, Dec. 7th and also provides a sleek second half to the housing. With this piece, we were encountering dishing, but adjusting the pressure profile and packing time allowed us to improve this aspect. Though sleek, this part has the defect of a scratch present in the biggest outer diameter of the part. It is due to a scratch that was present in the cavity, but that we had not noticed and then had no time to fix. Below is an image.

Now, finally, images of the yo-yo in separate pieces and the assembled yo-yos can be seen below.

Thermoforming- We had some issues with the original design of having to half that would fold and hold together via a series of positive/negative holes. the issue encountered was that getting the holes to work was not working. Thus, we pivoted to a Duncan yo-yo inspired design of casing, but with our own creative flavor. Below you can see the old mold (greater in length) to the new mold (with a dome life feature).

Furthermore, here is the finished thermoforming casing that is held in place with the use of papers.

If you want to learn more about what the team has been doing these past few weeks, please read the paper placed blow, as well as out team vide!

Watch our amazing Team Tropical Escape video here!

Our final report can be found here.

Extra information/all we have handed in this semester can be found here.

We would like to thank the 2.008 staff, Prof. Hart and Dr. Wendell, as well as the TAs and the shop staff for helping guide us in this journey. We learned a great deal and have a fun yo-yo to show for it.

Team Tropical Escape!

It turns out mass production is difficult, especially when unsolicited problems arise. 

This week, we have been focusing on making our snap fits, overloading our stock line and our Bs. Below is chart of our tasks as well as the quantity that we need for the parts.

A. Snap Fit

We made our production run of 25 disturbed parts by allowing a piece of the part to get burnt.

However, we then struggled to remove this feature. We tried decreasing the injection pressure profile and the injection speed. That decreased the amount of burning but did not entirely eliminated it. We then continued decreasing the injection speed a bit more drastically in order to fix the defect. In doing this, the snap ring showed no defects associated to decreased injection pressure, and that is why we decided to continue tinkering with this parameter. What did finally work was scratching both the cavity and core in the area where the burn was occurring. 

Tropical Escape began final production runs the Wednesday before Thanksgiving, November 20th. Our final 'B's  were produced!

To try get rid of dishing, we went over different parameters and increased the speed profile, increased the hold time, and played with decreasing the cooling time. The final numbers used were the following:

60 pieces were produced.

The stockline overmolds were also made!

For both pieces (B and stockline), the original color was intended to be gold (deviating from our original CAD design) because we believed it would provide portray a classier, more polished look. However, its contrast with the black was barely noticeable, so, we decided to switch back to a lime yellow color.

For our snap fits, we had fixed our design from last time because the inner diameter was too small to fit with our overmolded parts. However this time, it was too big by forty thousands (0.40").

We have been able to advance in preparing our spacers, by increasing 0.25" inner diameters by around one thousands. 71 of these have been fabricated and are ready to go. Our last piece of the project is the thermoformed packaging. Various iterations were performed last Friday to test parameters, and we are having some trouble getting the two halves of the packaging to stay together. We will be re-machining a new mold to adjust for this.

Next week is our last week for full production, as the final presentations will be Wednesday, December 12th. Our schedule for next week is:

More updates coming the following week!

Team Tropical Escape!