Molding and Casting
Part OneMaking the Design using Inkscape and Blender
Part TwoMilling the Wax
Part ThreeMaking the Mold
Part Four The Files
Making the Design using Inkscape and Blender
![](images/09gimp.jpg)
My instuctor, Ferdi, told me of that his Brazilian friends own a restaurant and they want a mold for Paçoca, a Brazilian sweet made out of ground peanuts, cassava flour, sugar and salt. It is typical of the Caipira cuisine- never heard of it!
I happily obliged in creating a mold for them to use for their homemade peanut sweets.
It was agreed to make the mold in the shape of an "M" from the packet:
![](images/09packet.jpg)
First I downloaded this image from the internet and cut out the "M" from Mini and made a black and white image- easy for tracing.
Next I imported into inkscape and set about vectorizing the letter M, using the Edit path by Nodes. The correct combination of vector points and click drags - and using click-drag -shift to create sharp corners, I traced the outline:
![](images/09ink.jpg)
Then importing as a .SVG file to Blender, I:
- make a mesh from the curve.
- extrude to create a volume shape
- add modifier- Remesh
- remove doubles
- go to edit mode/ wireframe, in Front Ortho View.
- remove doubles
- use "B" to box select the area that I want to smooth out
- smooth vertex, x 100, I do this 5 times (so x500 in total) to get a nice rounded shape.
- cut out the bottom by box selecting and deleting all vertices
- select non-manifold to select the open edge
- hit "F" to create a new face
![](images/09blend.jpg)
![](images/09jj.jpg)
![](images/09mani.jpg)
Next I added a molding box, which had to be lipped inside to allow easy removal of the cast.
![](images/09case.jpg)
![](images/09mold.jpg)
Milling the Wax
I used the Roland SRM-20 milling machine. I sent the .stl file to Modela Player 4. Unfortunately when I exported the .stl file, I forgot to "j" for join the box to the M shape, so only the M got imported. Fortunately the Modela Player 4 has options to create the box also. The box was adjusted to be a trapezoid, to ease the pulling out of the final mold.
Roughing stage was made with the 1/8 mill bit, and the finishing with the 1/32 mill bit. For the finishing we had decided to do along the X and Y axis (two passes) which I think is why the resulting piece has such great resolution.
Milling would stop when the computer went to sleep, so I changed the computer's settings and let the machine mill overnight as my time was up...if only Fab Lab Bcn could be 24h!
Making the Mold
I am making a food mold, so I am using Smooth- Sil 940 Platinum Silicone Rubber Compound for food related applications. I mix 10 parts of A with 1 part B. After measuring out the mixture I give it a good stirring, ensuring even mixing. Then place the mixture into the vaccuum to remove bubbles, before pouring it into the wax mold.
![](images/09mea.jpg)
![](images/09mes.jpg)
![](images/09me.jpg)
![](images/09vac.jpg)
![](images/09pour.jpg)
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It apparently takes 4 hours to set. I left it over night and took it out the next day. However while taking it out I managed to break off one edge of the wax model. It is an interesting note to ensure sufficient distance between the edges of other molds.
![](images/09broke.jpg)
I am really amazed by the result I hope in Brazil it will serve its purpose.
The "M" mold form can be downloaded here