Capturing Our Desired Design

Over the past couple weeks, we’ve experienced some machining set-backs, but we have successfully machined all of our molds (except the photo mold, which will be machined today in class!). We have created our first assembled yoyo, which can be seen in the picture at the right

. One of the issues that we had was that we accidentally machined our holes too large for our dowel pins, so we had to remachine the cores of the top and bottom camera piece with a smaller diameter. We then had to ream our holes and press fit in our dowel pins. We learned that the difference between what should work in paper and what does in real life is significant: our holes needed to fit 5/64” pins, but we ended up only reaming to .076” because the holes were too large the previous time. This time they fit perfectly, which was super satisfying for our team. Previously, we had used Loctite, which had super inconsistent results - one of our dowel pins fell into the mold and the other one broke right off.

We also have made progress on our thermoforming pieces. We have printed several of the pattern we need on the Mimaki and have learned how to use the thermoforming machine to complete the process. We learned that the trimming process is not always the best for aligning our parts correctly, so we have been taking care to make sure that we trim them in the desired configuration.

Now, it is time for our team to hone in on injection molding and set our final parameters. We have reduced flash on our parts, so we are pretty happy with our shot size, but we are still looking to refine our pressures and cooling times, as needed. We have learned that every time we run a part we are getting new behavior from the previous one because the molds have heated up and haven’t had time to cool. This has resulted in some undesirable behavior in between different runs with the same parameters, so we will be looking to troubleshoot this issue, so we can get more consistent parts. We are also looking forward to adding colors to our pieces as we prepare to injection mold our final products! 

We started press-fitting in our magnets right after injection molding, which proved to be the best way to insert them. When we waited too long after injection molding to press them in, they had cooled and it was almost impossible to insert them. We will need to ensure that the magnets are still performing correctly though, so this will be part of what we investigate this week.

The aspect of our design that we are most anxious about is our photo and the magnetic attraction that will hold it in place. We are trying to move as quickly as possible on the photo mold, so that we can verify that our set-up will work. It’s go time, but we’re feeling good about our progress and are excited to keep seeing the results of our efforts!