For our final project, my partner Aditi and I casted 8 Groot chess pieces! We first started off by exploring Thingiverse to see what our options were. We came across Marvel BabyGroot Chess by Houby! We inspected the STL file to make sure there weren’t any overhangs or empty spaces to ensure that we would be able to 3D print, mold, and cast successfully.
Once we were content with Groot’s file, we followed the pre-process instructions given to us on how to create the mold for our chess piece using MeshMixer, SolidWorks, and Fusion 360. We used MeshMixer to split Groot in half and reduce the number of triangles. Next, we used SolidWorks to create the mold with registration pins for both halves. We had to create two separate molds for both halves because Groot is not symmetrical. Then, we used Fusion 360 to prepare the file for the CNC machine. Once we were done with all of the pre-processing instructions, it was time to start the physical prototyping and fabrication process of the project!
We 3D printed our mold using one of the FFF printers at OEDK. We were able to print both halves on the same bed so our print took 6 hours and 45 minutes in total. Below you can see what our printed mold looked like.
The next step was to prepare our prints to pour in silicone to create the molds. There was a little concern regarding if the registration pins were too close to the edge. To combat that issue, we placed clay around the edges while creating our cardboard walls and base. This can be seen below.
We were confident and content with our preparation and ensured that there were no gaps for silicone to leak through via the use of hot glue. We were ready for the silicone! We calculated the volume of silicone needed based off of our STL files. We came to a conclusion that we needed 160 g of each Part A and Part B. This can out to be about 5-6 fluid ounces of each part. We then mixed both parts together. After we mixed them, we vigorously tapped the cup against the table to force the bubbles to come to the surface and pop. Doing this ensured that we wouldn’t have too many problems with bubbles forming on the surface of Groot, consequently affecting our chess piece. After we tapped out most of the major bubbles, we were ready to pour! Below you can see our pour.
We let it set overnight and came back the next morning to de-mold! Unfortunately, we found out that using clay negatively affected the silicone curing process. As you can see below, parts of the silicone mold were slimy and not dried and cured.
On the bright side, Groot looked great, which is the most important part of the mold! We moved onto the next part which was to start casting liquid plastic into the mold. Our Groot chess piece was pretty much exactly 1 fluid ounce so we mixed together 0.5 fluid ounces of each Part A and Part B. We quickly stirred them together because it had a very fast pot/pour life.
As seen above, we used rubber bands and weights to keep the mold together. This ensured that we would have a tighter seal and not have too much liquid plastic leak. After 30 minutes, we de-molded our first Groot which can be seen below!
We repeated this process 7 more times to get a total of 8 pieces! Below are the 8 Groots prior to post-processing.
It can be seen that the liquid plastic came out a little bit around Groot where the molds come together. We were able to easily fix this by using an x-acto knife and 400 grit sandpaper to get rid of the edges. We cleaned our Groots and they looked so much better, as seen below! Groot is an ally of the Pink Tax Repeal Act!
After we got rid of the excess plastic, we spray painted them white and put on a clear coat. Below are our final 8 Groot chess pieces!
Overall, we really enjoyed this project! It’s really hard to be upset when Groot is such a cute character!
Cost Estimate
Mold 3D print=$1.40
3D printer rental: $12/hr=$81
Silicone=$6.70
Liquid plastic=$0.57
Labor:$20/hr=$400
TOTAL=$489.67
