7. Molding and Casting
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- Design Challenge: design a 3D mold, machine it, and use it to cast parts
- Software: Fusion 360, Rhino, V-carve
- Machine: Tabletop ShopBot
- Date Completed: 10.31.17
Group Assignment
Rob led us and explored molding and casting materials. We tried hydro-stone and metal with the mold made out of oomoo.
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- Top left: Mixing hydro-stone.
- Top right: Rob is showing us the low melt fusible bismuth based alloy ingot.
- Bottom left: Pouring melting alloy to the oomoo mold.
- Bottom right: Waiting for the alloy to solidify.
Looking for food safe material
I want to make a mold that I have the chance to use more than once, so I decide to make something food safe, and I can use to make chocolate. I took a field trip to Reynoldsam and brought the SORTA-Clear® 18. I enjoyed the visit there and checked out all the awesome works they do.
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Design
I used fusion360 to design the model.
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Since Christmas is coming, I want to make something that is about Christmas and also fun to play. I have come up this idea of designing a Christmas tree using chocolate inspired by CNC design.
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Machine cutting model
I had run into a mysterious issue when I tried to use Shopbot to cut my model on machinable wax. The components of my 3d design disappeared once I imported them into the V-Carve.
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Then, one of the TA thought it could be the reason that components are not grouped. Then we generated a flat board underneath my design. We imported it again, and only see this flat board in toolpath.
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After troubleshooting and changing all kinds of possible bugs, TA came up this idea flipping the entire design 180 degrees. Finally, it works!
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We created three toolpaths: cutting straight, cutting 45 degrees and cutting -45 degree.
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Making silicone mold
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- Top left: Although you can’t tell by just looking at it, shopbot gave me a very smooth surface that was out of my expectation.
- Top right: Since my wax is not big enough, I ran out of space for the edge. I have to use tape to make a wall to keep silicone from leaking.
- Bottom left: Mixing SORTA-Clear 18 according to the safety data sheets: 100A : 10B by weight.
- Bottom right:I tried to pop up the big bubble.
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Unfortunately, my first silicone mold was not perfect. I washed wax before making the mold and didn’t dry it completely. I left water inside the hole that prevents my mold from curing the stick ( for making holes in the chocolate).
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I had to create a new mold! I was very careful when pouring the mixture into the model and making sure that all the holes were filled with mixture.
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Then, I put the mold in in the oven and baked for 2 hours under 176°F according to the safety data sheet.
Making chocolate!
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My first chocolate tree failed because the temperature that I used to melt chocolate was too high. I put chocolate in the pot and cooked it directly. It never re-solidified. Then, I looked online and found that we are not supposed to melt chocolate under high temperature. I came up this idea of melting chocolate over boiled water, and it worked.
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