Almudena and I decided on making King chess pieces with a fun twist to the forms. After downloading the stl from Thingiverse, we prepared the file to 3d print the molds. We cut the piece in half and built a box around it with opposing pegs and holes for the mold to eventually fit together. Since our piece was symmetrical, we decided to just make 1 half and pour the silicone mold twice to make 2 sides from 1 3d printed part.

Since the silicone material is quite expensive ($400 for the large bottles), we calculated the volume inside our 3d printed mold in Solidworks. It was around 75 ml, so we mixed about 90 ml (45ml Part A and 45ml Part B) to make sure we had enough to fill the mold. Using a tip we saw Taekyeom Lee use, we thinly brushed the 3d printed part with soap foam to hopefully help the silicone easily release. We then poured the silicone and waited for it to cure. * We waited the 4 hours for one half, but for the other we heated the material with a heat gun to speed up the cure time bc we were impatient. We noticed lots of airbubbles in the silicone, so with the first half we tried to carefully fill them with leftover silicone to smooth out the mold- though this was not very successful.

We then started casting our pieces! For the first piece, we mixed 7.5 cc of Part A with 7.5 cc of Part B, stirred for a little under a minute, and poured it into our mold. We poured and little plastic and moved it around the try to get it in all the crevices before filling the mold. We let it cure and quickly turn white for about 10-12 minutes and then carefully demolded by pulling the halves apart. We repeated this for our 8 pieces!

Our pieces needed a bit of work after coming out of the mold. We had lots of air bubbles in the silicone mold, which led to bubbles of material sticking out of the chess pieces, and a bit of lost definition around the top. To post process theses, we removed the bubbles and extra material with an exacto knife and used sandpaper to smooth the bubbles. Reflecting on our process, we believe the bubbles in the silicone may have been caused by the soap we put on the 3d printed part.

We also tried one piece with food coloring mixed in (only because Dr. Wettergreen let us try it) and made a bit of a chemical reaction, which is why one of our pieces is speckled green!

While our pieces don’t look flawless or exactly uniform, we learned a lot about molding and casting through this process and perfected our ability to notice small details!

 

Cost Estimate

Labor: 5 hours @ $15/hr = $75

3d printed mold: $0.66

Silicone mold: $362 for 2 gal (used 180ml) = $9.08

Liquid plastic: $148 for 2 gal (used 45 ml) = $0.85

Sandpaper, plastic cups, and 3d printers not included since they are common resources in the OEDK.

Total Cost: $85.59