For this project, my partner and I started by looking on thingiverse to find an .stl file for an object we liked. We knew we wanted to do something a little different from a regular chess piece, but we were having a lot of trouble finding something that would work on the carvey. Eventually, we decided to make the knight from this chess set on thingiverse.
We started by 3D printing a positive of the chess piece, just to see what it would look like. We also 3D printed one half of our mold, using meshmixer and thingiverse to set it up.
Once we had this, we went on to the carvey step, which was a lot more involved. First, we used fusion 360 to generate the G-code, and then we imported it into Easel to cut.
The left side of our chess piece imported into Fusion 360 for manufacturing. The four circular pegs in the backplate are meant to allow the final molds to align with each other for consistent casts.
This screenshot shows the planned toolpaths for the CNC machine in order to carve the left side into a wooden 2×4.
Our first cut on the carvey went well, and as it turns out we should have stopped there, because when we went to do the smoothing cut, there was an issue where it started stepping over. This cut into one side of our knight, as seen below.
After this, the carvey was down, and Danny and Fernando said not to keep messing with it. So we made two more 3D printed sides of the mold, one with original shape that should match the CNC part and the other with a modified shape where we attempted to mimic the failure. Once these printed, we used boxes of indeterminate sizes to make molds of the 3 components.
Each mold (green) after being poured over the CNC part (top left) or a 3D-printed part (right, bottom). Two of the molds will fit together later to create full chess pieces from the two halves.
The next day, we removed the molds and began casting! First we cast two pieces, one with each 3D printed side, and decided that the 3D printed side that retained the original geometry looked much better, so we made four more pieces with that mold, mixing dyes and colors so it looked more interesting. When each piece was removed from the mold, it looked like the image below, with a seam where the two halves of the mold didn’t quite match up, and a bulge on the bottom where the plastic was poured in. The bottom peg is an artifact of the casting process, since there needed to be a hole in the mold for pouring the plastic. The peg is removed in post-processing to produce a final chess piece.
We used a Dremel to get rid of this excess material, and then briefly pushed the bottom of each piece on the belt sander to ensure a smooth finish. Here are the results of the whole process:
These images show all six of our chess pieces. We experimented with dyes to create some interesting color effects.
As you can see, the unfortunate incident where the carvey stepped over resulted in some unevenness in the back seam of our knights. This is especially noticeable at the very tops of the pieces. Still, we tried to mitigate this issue as best we could, and overall we are still fairly satisfied with the result.
Cost
- PLA: $1.78 for all 4 3D printed parts (according to 3D printer OS)
- Wood: $1.75 (assuming our piece was ~12 square inches and wood is ~$7 per 48 square inches)
- Silicone: $43.2 (assuming ~150mL per half mold at a price of $96/L)
- Plastic: $8.64 (assuming ~30mL per piece at a cost of $48/L)
- Dye: negligible (used very little)
- Labor: $132 (12 hours between the two of us, assuming OEDK lab assistant cost of $11/hour)
Total: $187.37
