13. Molding and Casting¶
Individual Assignment¶
- Design a mold around the process you’ll be using, produce it with a smooth surface finish that does not show the production process, and use it to cast parts.
Making Mold¶
First, I needed to create a 3D print that was very high quality to avoid as many layer lines as possible. I used the design from machine week which is linked below.
Then, I used silicone for my mold because Dr. Taylor said that if you want the cast to be hard, the mold needs to be soft, so I had to choose a material that would make a soft mold.
First, I read the data sheet for the silicon because I wanted to know how much of Part A and Part B I needed. It turned out to be a 1:1 ratio, so I mixed even amounts of each. I then placed the 3D print into a red solo cup and poured the mixture over it.
There was plenty of pot time, so I did not need to worry about pouring the mixture immediately although I still did it relatively quickly. Unfortunately, I did not realize I had to glue the 3D print to the bottom of the cup in order for it to stay down, so I had to sit there holding it down with a chopstick until the silicone hardened enough for the 3D print to stay in place.
This is me holding the 3D print down with a chopstick:
This is the mold being formed:
The mold finished in four hours. To take the 3D print out of the mold, we had to cut the top part of the mold open a bit. We used a knife to cut an X-shape into the top of the mold.
This is my finished mold:
You can kind of see Neil’s face in the silicone if you look for it.
Casting¶
Next, I had to choose a hard material to cast with. I ended up choosing resin. The resin I used had equal amounts of Part A and B as well.
Here are the two parts before being mixed:
We did a brief water displacement measurement with the 3D print first to get a general idea of how much resin would be necessary so that we would not make too much. The resin had a MUCH quicker pot time (2 minutes), so once the two parts were poured together, it was crucial to move quickly. We made sure to shake the bottles of the resin parts before pouring them and stirred them as well before mixing them together. Once both parts were poured together, I stirred them until the cup started to feel warm and then Elle and I poured the mixture into our molds. I had to use a funnel for my mold because the top cuts were not very large, and we wanted to be very accurate with the pour, so Mr. Dubick suggested a funnel.
Here is a video of us mixing the two parts:
Here is a video of us pouring the mixture into my mold:
Here is the filled mold:
It was very messy, so we did it over sheets of cardboard to keep the table from getting destroyed.
Here is the finished cast in the mold:
Here is the finished cast once it was taken out of the mold:
It was quite difficult to remove the head from the mold, and I had to do it using the corner of a table, a knife, and the help of Elle Hahn, which I was very grateful for.
Luckily, I was able to use the mold again. However, there was a slight rip in the side, so I covered it with packaging tape and then duct tape on top. Mr. Dubick warned me about not using tape with sulfur because some materials for casting would not work if they were touching sulfur.
The tape did not work great, and I ended up having to cut the mold open to get the cast out. It was okay though because I had already made one successful cast.
Here is the second cast:
Here is the cut mold:
Group Assignment¶
Our group assignment for this week was to review the safety data sheets for each of your molding and casting materials, make and compare test casts with each of them, and compare printing vs milling molds. I worked with the same group as last week which was Elle Hahn and Cooper Cumbus. Here is a link to our group work for this week.
Reflection¶
This week was pretty fun and easy which was nice after machine week. I liked molding and casting and will definitely try to incorporate it into my final project if need be.
Files¶
Stl design I used for Neil head