Hsing-yi and Paige decided to tackle this final project together and we had a really great time working together on it! We choose to do a cat king chess piece from Thingiverse.
Gate 1: 3D Printed Chess Piece
Figure 1: Initial 3D printing file
To begin, we printed the chess piece to decide on sizing. After our first print failed for unknown reasons, we printed 3 of different sizes so that we could quickly decide which would be the best for this project. We decided on 80mm as it was big enough that the cross wasn’t too small and but also the whole piece wasn’t too big.
Figure 2: Three options for sizing
Gate 2: 3D Printed Side of the Piece with Base
Next we decided on which side of the chess piece would be the CNC half and which would be the 3D printed half. This decision was based on the limitations of the CNC machine in that it can’t cut anything behind a protruding piece so we chose the side with the tail to be the 3D printed side.
We made our 3D file with half the chess piece, a mold base and an air hole to reduce air bubbles at the top of our piece when we got to the casting process.
Figure 3: 3D printing side with mold base
Figure 4: 3D printed side ready for being made into a mold
Gate 3: CNC Printed Side of the Piece with Base
We repeated the same process for the CNC side just without an air hole this time.
Figure 5: CNC 3D half with mold base
This file then had to be turned into a VCarve file so that CNC machine could carve it out.
Figure 6: VCarve file
After one failed attempt when we didn’t realize that the wood was oriented the wrong way around in the CNC machine, we had both halves needed to make the molds and finish the process!
Figure 7: CNC Half
Final Steps: Making the Molds and Casting the Chess Pieces
We made boxes around each of the bases using a lot of hot glue and duct tape to ensure that none of the mold liquid escaped.
Figure 8: 3D printed half with box ready for pour
We then mixed and poured the mold liquid into each of the boxes starting from a corner to reduce the formation of bubbles around the cat.
Figure 9: Pouring the mold mixture for the CNC half
We then removed the molds from the boxes and they were ready to be used to make the chess pieces.
Figure 10: Final molds
To begin with we did a couple of attempts of casting with two wrong materials and then realized that the material we were supposed to be using hadn’t arrived at the OEDK yet so we went back a couple of days later to try again.
We then used a 1:0.9 ratio by weight of part A and part B of castable resin TC-802 to make our chess pieces. We added the color to part A before mixing them together to ensure that it would mix in evenly without the time pressure of them starting cure.
Figure 11: Mixing the casting mixture together
We filled the mold with resin until it was close to the top and made it level using popsicle sticks as they weren’t the exact same height for some reason.
Figure 12: Using the molds to cast pieces
To post process the chess pieces we used a knife to cut off any extra material that has formed in the gaps between the molds. We then sanded what was left so that it was smooth. Our final product is a rainbow of cat chess pieces!
Figure 13: Our final cat chess pieces!
Figure 14: Our final cat chess pieces!
Cost of Production
3D Printing: 30g for Initial Sizing Prints at $27.99/kg from Bambu Lab is $0.84.
36g for Print with Mold Base at $27.99/kg is $1.01.
CNCing: 2x4in wood from Home Depot is $3.15 for 8ft. Including the failed cut we used 10in so $0.33.
Molding: $265 for 16lb kit from Brick in the Yard which is around 7500ml. We used 260ml so $9.19.
Casting: $129 for 15lb kit from Brick in the Yard which is around 7500ml. We used around 200ml so $3.44.
Labor: 25 hours at $15/hr is $375.
Miscellaneous Costs: 15% of total cost with includes OEDK provided materials like hot glue and cardboard, the usage of machines like the 3D printers and CNC machine and other OEDK costs like the Lab Assistants. This comes to $57.12.
Total Cost of Production: 446.93
Clean Work Space
Figure 15: Clean workspace
