For the final assignment, I decided to do a cat king chess piece because it seemed doable compared to other pieces I initially wanted to do. Although, I would later find out that the little cross and ears would be a cat-astrophe.
Preparing the file
I took the STL file from thingiverse and sliced it in half using Meshmixer. I got help creating the box with holes in Solidworks and making a vertically flipped version with alternating holes since the two halves are symmetrical. We also had to prepare the CNC file with a cut file in Fusion360 and import that into easel.
Molding and Casting
I was able to 3d print both halves off the prusia printers and then pour the silicon mold on top after glueing a box around both pieces. The mold came out a little thin because there wasn’t that much silicon mold material left and my initial one started leaking out a lot. I got some advice to glue the box done so the other mold wasn’t as unfurtunate. I thought the molds came out nice, although it was a little challenging doing the casting because they were so thin.
I mixed about 10 cc of Part A and 10 cc of Part B of liquid plastic for each piece. My first piece didn’t come out well so I figured I had to hold it in place stronger somehow. The rubber bands made the bottom of the mold bend too much so I conveniently wrapped it around a piece of wood on the table (shoutout to whoever’s that was and sorry for randomly using it). I got a little bored after casting several pieces so I tried adding some color by add by mixing in paint. I found that I needed to mix the paint evenly with Part B so that the color would be uniform. I mixed some other colors and adjusted the amount for several pieces. I tried pouring in two colors as well to see how that would turn out and I thought it came out pretty cool.
The struggles I faced included getting the plastic to pour into the ears and cross because they were too small. I tried turning and shaking the mold several ways and although that did make the next attempts better, I couldn’t get it to go all the way in. I also had some trouble getting the molds to line up because I couldn’t see far into it upside down so some of the tops of the pieces were slightly off and the line in the middle was clear. I think my mold wasn’t strong and stable enough to fit accurately so if there was more silicon mold material or if I did this project again I would ensure I got the right ratio and poured in more. I would also try to make sure the ears and cross was filled by possibly increasing the size of it or tilting the mold more when filling it with liquid plastic. Overall, I like the way my pieces turned out even though they’re not purrfect and the process of adding in colors was really fun for me.
Cost estimate
Labor: 6 hours @ $15/hr ≈ $90
3d printed pieces: 1.5 hours x 2 @ $3/hr ≈ $9.00
Silicon mold: $355.61 for 2 gal (0.032 used) ≈ $11.38
EasyFlo 60 Liquid plastic: $142.88 for 2 gal (0.024 used) = $3.43
Paint: 4 (1/2 tube) colors x $6.70 ≈ $13.40
Total Cost ≈ $127.21
