Come along as we (Sumin and Shane) take you through the process of how we made a pokeball chess piece! This project was very fun although required a lot of patience with many problems being encountered along the way.
Step 1: Choosing the design
We first wanted to go with one of the pokemon chess pieces on ‘Thingiverse’ but after realizing that they won’t be cut with the CNC machine, we decided to do a pokeball chess piece that looks like a pawn. We downloaded the file from Thingiverse and scaled and 3D printed it to see how it would actually turn out and to determine its size.
Step 2: Preparing the file and 3D printing half
We used Solidworks to prepare the file for the mold positive. We then exported the file as an STL file for it to be cut out using the 3D printer. Following the instructions on the document, we were able to cut the chess piece in half and add a base beneath with pegs and holes. Our first trial of 3D printing ran into an issue of the distance between the peg and edge and the distance between the hole and edge not being the same. However we successfully produced the 3D printed mold positive after making slight adjustments.
Step 3: Making the mold for the 3D printed half
Using the 3D printed mold positive, we made a silicone mold. We first cut out pieces of cardboard and used hot glue to glue the cardboard to the sides of the mold so that the solution could be poured into a ‘container’. We then measured the volume of our container and also the volume of the half of our chess piece. Since Part A and Part B of the silicon mold had to be 1:1 ratio in weight, we used the volumes we measured to determine the weight for each part. Then we prepared the silicone solution by mixing A and B for 2 mins with the appropriate weight we calculated. We poured the solution into our container slowly and subtly to prevent bubbles from forming, then waited for the mold to set.
Step 4: CNC cutting the other half
This process was done by finding a 1.5” x 3.5” piece of wood and placing it on the bed of the Shapeoko cutter. We used the same STL file for the CNC half as the 3D printed half as the pieces to be put together were symmetrical. This process took many attempts due to first attempting to cut it on the nomad cutter with no success, then realizing that every other group had success using the Shapeoko cutter. The problem we encountered with the nomad cutter was that the smoothing pass did not actually smooth the chess piece (in fact, it looked more rough than the original roughing pass). After 4 attempts on the nomad cutter and persistently trying to make it work, we decided to switch to the Shapeoko cutter. We followed the instructions on the CNC homework document as well as the videos provided by the TA’s on canvas which made our cut work the first time cutting. We did the rough cut using a ¼ inch down cut drill bit then switched to a 1/16 inch ballhead drill bit to smooth out the surface.
Step 5: Making the mold for CNC cut
Using the CNC positive mold cut, we made the other half’s silicone mold. Similar to making the mold for the 3D printed half, we measured out the volume of the container and made the exact same solution to be poured as a mold for the CNC cut. After mixing the solutions together, we carefully poured the solution into the CNC container without bubbles and waited a day for it to set.
Step 6: Putting it altogether
Once both molds were ready to be put together to make our final chess piece, we connected the molds together using the pegs and used 2 pieces of plywood to squeeze the molds together and held it tightly using rubber bands. To measure out how much of the solution we needed, we poured water into the final mold, then poured it back out into a cup in which we measured the volume of the water and divided it by 2 for the 1:1 ratio of the liquid plastic A and B. We replaced the water with the liquid plastic A and B solutions and mixed the solutions together by stirring constantly for 2 mins. We poured the solution slowly into the mold, rotated the mold to ensure that all surfaces were covered by the solution, then repeated this process until all the solution was poured into the mold. We then waited a day for the solution to be set.
Step 7: Finished pokeball chess piece
We took apart the molds holding the chess piece together and we were so happy to see that our chess piece turned out perfectly! We repeated this process 7 more times to complete the final 8 chess pieces to be turned in and we used dye for 4 of the chess pieces to create some variety.
Conclusion
Overall, this project was very fun but also time consuming due to difficulties finding a time slot to CNC cut our wood. One thing that can be improved could be starting the CNC cut earlier as this had delayed our progress by 1 week.
Cost Analysis:
- 1.5” x 3.5” x 7.5” plywood = $ 3.18 (Home Depot)
- Machining costs = $117.94 (Indeed)
- 10% of Silicone solution A & B = $ 130.99 x 0.1 = $ 13.1 (Specialty Resin and Chemical)
- 20% of liquid plastic A & B = $ 27.62 x 0.2 = $5.5 (Amazon)
- Labour = $300 (15 hours x 2 people x $10/hour)
TOTAL = $ 439.72
