Casting Chess Pieces!: Serena and Sophia’s Midterm Project

Creating custom chess pieces was an exciting challenge that pushed our skills in design, modeling, and manufacturing. From selecting a model and preparing molds to casting the final pieces, every step required precision and creativity. This project gave us the opportunity to combine digital tools with hands-on techniques, resulting in unique chess pieces that reflected our vision. Here’s a walkthrough of the process and what we learned along the way!

Pt I: Planning

When selecting a chess piece, we aimed to choose a model that matched our design preferences while remaining feasible to mill. To achieve this, we ensured there were no extreme overhangs or overly thin segments. While browsing 3D model websites, we discovered a WitChess set and were drawn to the wizard-style pieces, ultimately selecting the Bishop chess piece.

Our Chosen Chess Set

After 3D printing the STL of the Bishop, we inspected it for potential issues. We realized that a straightforward cut in half wouldn’t work; instead, the part would need to be cut at an angle to prevent the hat from creating an overhang during the CNC machining process.

Angle of Cut

Splitting the Part in Meshmixer

Front Piece of Mold in Solidworks

Pt 2: 3D Printed Mold

We 3D printed the mold and used silicone to cast it, constructing the bounding box out of cardboard held together with a glue gun. The final result was accurate and included a well-positioned fill hole.

3D Printed Mold

Measuring Silicon

Constructing Bounding Box

Poured Silicone Mold

Pt 3: CNC Mold

We CNC-machined the back half of the mold, which required additional finishing due to artifacts left by the drill. A significant amount of filing was needed, and a noticeable lip created by the CNC would have caused a gap in the final part if left unaddressed. We sanded the lip as thoroughly as possible and, following Dr. Wettergreen’s advice, planned to use superglue or clay to seal it and prevent it from affecting the final part.

CNCing the Mold

 

CNCed Mold

CNCed Mold Post-Filing

Once again, we used silicone to cast the mold, constructing the bounding box from cardboard and securing it with a glue gun. While the result was accurate and featured a well-placed fill hole, removing the silicone from the CNC mold was more difficult compared to the 3D-printed mold. Ultimately, we succeeded and prepared an accurate mold for casting. To address the negative space left by the redundant lip, we filled it with hot glue.

Pt 4: Final Casting 

It was time to cast the final chess pieces! We needed to create a total of four pieces. To prevent any leakage of the casting material—polyurethane—we secured the two parts of the mold together with multiple rubber bands. Before mixing, we determined the volume of our part using SolidWorks, then combined equal parts of Component A and Component B to create the full volume of polyurethane needed for casting.

We wanted each of the four pieces to be a different color. Three were dyed green, blue, and black, while the first piece was left undyed as a test run.

Casting the Polyurethane for the First Time

Hardening Polyurethane

After preparing the polyurethane, we poured it into the mold and waited 10 minutes for it to set. Unfortunately, we removed the first piece too early, which caused minor damage to the Bishop’s hat. For the remaining three pieces, we were careful to monitor the timing and ensure the polyurethane was fully set. Each piece had minor artifacts from the manufacturing process, such as slight leakage along the seams, which we trimmed to make the edges smoother and less noticeable.

Final Pieces!

We are thrilled with the final results. The pieces closely match their original models, with no significant discrepancies or misalignments. The smooth congruency of the parts exceeded our expectations. This project was both rewarding and educational, providing us with valuable insights into proper mold preparation, SolidWorks modeling, MeshMixer configuration, VCarve, and CNC machining. It taught us the level of care and diligence required to ensure a high-quality final product. Seeing the various processes come together to create these pieces was incredibly satisfying. We both enjoyed the experience and hope to work on molding projects again in the future.

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