I was really excited about this week. After Rob showed us that we could use tin bismuth for our molds, I knew that I wanted to make a ring using the material. I used Fusion 360 to design the ring.
I was really excited about this week. After Rob showed us that we could use tin bismuth for our molds, I knew that I wanted to make a ring using the material. I used Fusion 360 to design the ring.
In order for the mold to have an opening to pour in the material and a vent for the air, I needed to design two cylinders that opened from the ring. This would be a two part mold, with the ring cut at the center.
I exported the STL file and moved it into VCarve to create the toolpaths. I set three different toolpaths: one for roughing, and two for finishing. The finishing toolpaths settings were the same, just rotated by 90 degrees.
VCarve has a nice option that lets you preview what the finished result will look like. I exported the toothpaths into an SBP format, and loaded it onto the shopbot machine.
The surface we were cutting into was a wax block, and I fastened it onto the bottom of the shopbot with double sided tape. After zero-ing the origins and choosing the right bit, the machine started milling.
Final result from the mill.
Next, I mixed the OOMOO to create the cast. The porportions were 1:1, creating a nice sky blue color.
Next, I vacuumed out all the air bubbles.
Then, I poured the OOMO mix into the wax mold and let it sit for 1.5 hours.
After the OOMO cured, I pulled it out and repeated the steps again to create the second mold.
Next, I needed to extend my vents since VCarve doesn't allow you to move your material to the edge. I used a razor to cut a funnel shape to enable the bismuth to soak in.
I put a bar of tin bismuth into the oven and set it at 450 degrees and hit bake for 30 min. When it's ready, it becomes a liquid, ready to pour.
I clamped the molds in to pour the bismith.
Result after the ring dries.
Last step: using the dremel to polish.
Final ring!