My wife was given a silicone ice cube mold with a particular brand embossed into it. It makes ice cubes with words on them. For some reason, this amused me, so I decided to make my own version just for fun. This document is a running project log of designing and casting my own silicone molds. The journey is still in progress. **Current Status**: To provide a quick overview, here are some of the key outcomes and challenges so far: Successes: - Achieved minimal flashing and no significant leaks in the mold. - Successfully removed ice without cracking or sticking issues. Failures: - Sides of the ice cube bulge during freezing, affecting shape. - Current embossing depth doesn't achieve the desired boldness. Open Questions: - How can the shape stability be improved further? - What adjustments will give a clearer embossing on the ice? ## Project goal Make a one-cube silicone ice mold that: - produces a crisp, readable embossed mark - stays square while freezing (no bulging sides) - releases the ice without a fight For the first tests, I kept the “word” simple: a monogram of my initial using the Luminari font. The current version is purely a proof of concept. ## Materials and tooling - CAD: Fusion (modeled the cube and monogram) - Mold housing kit: [https://www.amazon.com/dp/B0CRVCFMJN](https://www.amazon.com/dp/B0CRVCFMJN?utm_source=chatgpt.com) - Silicone under test (Siraya Tech): [https://siraya.tech/collections/silicone](https://siraya.tech/collections/silicone?utm_source=chatgpt.com) - testing both 10A and 25A - Master pattern fabrication: - revision 1 printed on [[Trellium]] in PLA (FDM) ## Design approach I modeled a positive “master” (the cube with raised monogram), then cast silicone around it to create the negative cavity. Emboss orientation: the monogram is on the bottom of the mold, opposite the opening. I placed the embossed face of the ice cube against the closed end of the cavity. One cube per mold. ## Mold box setup I was supposed to tape the seams of the housing kit, according to the manufacturer. However, I decided to experiment by skipping the tape and instead ensuring a precise fit. My hypothesis was that a snug fit using just the model base could prevent leaks and minimize flashing. **Result**: minimal flashing and no significant leaks. ## Revision 1 ### Design parameters - Form is 50 mm - Cube is 50 mm - 4 mm (46 mm) - 2 mm walls - 1 mm emboss ### Master fabrication - FDM PLA print - No post-processing after removing the part from the printer - No sealing ### Silicone casting process - Mixed 1:1 as directed by the manufacturer - Batch size: 60 mL - No vacuum chamber - If I keep enjoying silicone work, I’ll likely buy one (also useful for epoxy) - No mold release - Cured for 4 hours - I went with the low end of the recommended range because the walls were thin. - Room temperature during cure: 72°F I do see trapped bubbles in the silicone. They don’t impact the surface finish of the cube. ### Freezing test - about 3 hours at -6°F ## Results of revision 1 - 25A is more well-suited than 10A - 3 mm walls will be implemented to improve structural integrity. 2 mm walls are too thin, leading to bulging during freezing and distorting the cube. - 1 mm embossing is too shallow - The monogram transfers, but it isn’t as bold/crisp as I want - FDM layer lines and surface texture transfer very clearly into the silicone - A smooth surface was not a design goal; it was just a discovery from the first attempt. Demolding notes: - Removing the ice was easy. - I could peel the silicone away from the formed ice. - The ice did not crack around the emboss during release. - I did not notice frosting or opacity differences between the embossed face and other faces. ## Plans for revision 2 - 3 mm walls - 3 mm embossing - Resin-printed master instead of FDM - Standard wash/cure processing (no special finishing planned right now) ## Potential future tests - Add a draft angle to encourage the ice to expand upward toward the opening. This adjustment is expected to reduce side bulge, resulting in a more uniform cube shape. - Add a brim to stiffen the walls, which should improve mold stability and decrease wall deformation. - Insert silicone sleeves into a rigid tray to enhance structural support and keep the sides square. Enable stacking. ## Next steps - Update Fusion model for 3 mm walls and 3 mm emboss depth - Resin print the revised master. - Cast again (likely focusing on 25A) - Freeze test and compare: - squareness - emboss readability - surface finish - ease of release ![[Discussions]]