Week 8
Molding and Casting
This week's assignment: design a mold, mill it, and use it to cast parts.
This week was super cool! Anthony (aka the best TA) had Jeremy's pawn that he made for this assignment a couple of years
ago as an example, and I thought it was so cute that I wanted to make a chess piece myself (I also just
like playing chess). I designed a Mickey Mouse king chess piece in Fusion 360,
put it in a 3" x 7" x 1.5" block, and did the CAM for it using Adaptive Clearing with the 1/4" end mill, following
Anthony's recitation tutorial. I also added connectors/holes to make it easier to connect the two molds for
each side of the chess piece.
![](../images/week8/cad.png)
When Anthony inspected my CAM, he enlightened me that it sucked - for example, my surfaces were very hilly and
the holes hadn't been drilled, none of which I'd noticed.
![](../images/week8/hills.png)
Hills
So we added a drill operation for the holes, and a contour, parallel, and pencil operation with the 1/8"
end mill to smooth out the surfaces of the piece. Then we milled my mold in wax using the ShopBot
in the EDS!
Adaptive Clearing Pass
Parallel Pass
![](../images/week8/wax1.jpg)
![](../images/week8/wax2.jpg)
The left pic shows the mold after just the adaptive clearing and drill passes. Good thing we added the extra CAM,
otherwise my piece would've been very ugly! Next, I filled my wax mold with Oomoo twice to get two molds,
one for each half of the chess piece. I waited ~3 hours for the Oomoo to set for each mold.
![](../images/week8/oomoo.jpg)
![](../images/week8/oomoo_mold.jpg)
I then attached the Oomoo molds together, cut a hole at the top so I could pour Drystone in it, and added rubber
bands for extra stability. I mixed Drystone with water in a 1:5 ratio of water:drystone (it's important to pour
Drystone into water and not the other way around!) and poured it into the
mold to cast my part. I cut the hole too small so it took forever to shove the Drystone in there. After ~30 min, I took
my chess piece out of the mold. There were a lot of random stubs since my molds weren't pressed together fully,
so I cut those off while the Drystone was softer and not fully set.
![](../images/week8/drystone.jpg)
![](../images/week8/uncut_piece.jpg)
Here is the final product! I think it's pretty cute!
![](../images/week8/final_piece.jpg)
![](../images/week8/jeremy.png)