A knook is an internet meme chess piece that can move the same as a rook and a knight. For our final project, we took it upon ourselves to recreate knooks by using CNC and 3d printed molding techniques. The first step was to design the knook in CAD. It was then split in half and we designed molds complete with alignment holes, a profile fin to line up the seams, and a channel to allow air to escape when casting. We then CNCed and 3d printed the positives for our molds. While 3d printing went relatively smoothly, the CNC machine was much harder to tame and it ultimately took 4 attempts to get a decent positive. This was because we had issues with the machine skipping steps and adhesion to the machine. Next, we cast the negatives for our piece out of silicone. Our original pour for the CNC side failed, perhaps due to under-mixing, so we had to redo one of them. We used a system of laser-cut plates and wooden pegs to apply consistent pressure and ensure alignment when molding. Below are images showing the mold design and the molds in action.
We used a few different techniques when casting to get a variety of different colors and patterns. We used solid colors, we swirled in dye for a marble effect, and we painted the inside of the mold with dye to create a splotched effect. Overall, we were pleased with the casts, although we wish we has access to a vacuum chamber to better mitigate bubbles in our casts, especially due to the intricate nature of our mold.
Overall, this project was fun and I am glad we went for a complicated design, even though it took a lot of work to eventually get working.
Cost breakdown:
- 3d printed positive mold: $2
- Stock 2×4 for CNC material: $3.25
- 8 lb. kit of Platsil 73-25 silicone mold material is $179, we used about 12 ounces in the three molds we made (including one failed one), so about $18 for the molds
- EasyFlo 60 liquid plastic is $150 for a 15.2 pound kit, we used 1.5 ounces per cast, so for 8 knooks this comes out to 12 ounces, or $7.40
- For laser cut wood and dowels, along with stir sticks and mixing cups, an estimated $5 was used
This comes out to about $35 for materials. We spent around 20 combined hours on this project, which at $15 an hour comes out to $300. Final cost of materials and labor then comes out to $335 or ~$42 per knook. We anticipate as this scales, the cost per knook would be much cheaper.
