For this week's assignment, I wanted to design a necklace pendant. The plan was to create a pendant design and CAD a box around it to create a mold. Into this 3D printed mold, I would pour silicon and then I would pour the metal into this silicone mold to create my pendent. I first CADed in fusion 360 the positives of two different pendant designs. Then I created boxes around them to make the molds.

After 3D printing my molds, I used sandpaper to create a smooth surface finish. I sanded it with 120, 220, and then 320 grit sandpaper. To prep my molds, I also rubbed a thin layer of silicon on them. I then prepared the OOMOO 25 silicon. I first mixed each of the two liquids individually and tapped them on the table to get the air bubbles out. Then I mixed them together in an equal ratio and again tapped to get air bubbles out. There were more air bubbles in my mixture than in the one in the training, so I think when I mixed I did inefficiently and got air bubbles in. After giving up on the number of air bubbles in my mixture, I poured the silicon into my 3d printed molds. I then tapped the molds on the table to hopefully get more air bubbles out.

I came back 3 days later, due to the long weekend and took out my molds. Unfortunately, one of the pendants had what I think is an air bubble and one of the holes did not properly get filled with silicon. I also realized that one of my pegs did not get parametrically CADed properly and one of my pegs was bigger than the rest. I used a razor blade to remove this peg, so my two part mold would work.

Then it came to metal casting where Gert informed me that it would actually be easier to make mine as a one part mold because he observed that the metal does not stay very liquidy and has been getting blocked at the inlet. So I ended up casting my molds as one piece molds. Before casting the metal, I brushed cornstarch on the mold.

When casting my pendants, we struggled with how small the channels of my designs were as the metal was viscous when pouring. The first attempts for both my pendent designs were unsatisfactory, with the star not getting enough metal and the metal in the blob spilling over. The pan we were using to heat the metal was big compared to the size of my mold, which made it difficult to control the pour. Additionally, after feeling the weight of the pendants I also realized that these pendants are likely too heavy to be worn. I wanted to figure out how to better cast them, so we melted these pendants and decided to focus on the star pendant. We realized that the metal tray we were pouring one was not flat, so at first I tried putting the star in the middle of it and pouring in the center, hoping gravity would have the metal go to each of the points. This worked better than the first attempt but was not quite there.

For the second attempt, I decided to place the mold on a flat surface and then pour metal in at the corners. This gave me a satisfactory result.

Afterwards, I used a saw and a file to remove some of the undesired pieces on the star. My time was cut short by needing to go to a class meeting for machine week, but in the future I want to come back to post-process my pendants more and make the whole go through so I can wear them (or likely use them as keychains).