Week 12 - Molding and casting
Design the positive model:
My idea is to make a vertex to join the edges of a geodesic forms, to use it as a fogcatcher.
As you can see, in my garage's roof is build a geodesic, but with the joints in the vertex that are not the best alternative.
But the new model I want to build is a flat form based fogcatcher, a big one, that could be easily built, and could be modular.
I design my own alternative, using Autodesk Fusion 360. The files are here 
Mill the Wax on the Modella MX20
Materials:
- Machinable Wax
- Modella MX20 machine.
- Round head milling cutters
- Fab Modules software installed.
Install the milling in the Modela.
Place the wax rod sticked with a double contact tape in the surface of the Modela.
Open Fab Modules, load the .stl file.
Load .STL file
The process of Wax machining involves two phases: smoothing and finishing.
- Select milling cutter size, material and process: "mm, 1/8, wax, rough", to smooting I used this mill
Verify the milling cutter diameter has been adjusted: 3.175mm (corresponds to 1/8 inch), Offsets: -1, overlap: 0.25, 2D threshold: 0.5, error in pixeles: 1.5, 2D top z: 0
-Adjust the 3D parameters, the design depth and cutting dept
- Make .path
- Verify speed parameters: 20mm/s and jog: 1mm
- Adjust X, Y,Z axis of Modela
- Make .rlm and Send it
The Modela milling in the smoothing phase
The smooting phase is over
The finishing phase is quite similar, using another mill, and takes more time
Making a mold
Procedure:
- Place all the materials to be used, in an ventilated space: the wax positive mold, the liquid ruber, some paper towels, gloves, and recipients to blend the rubber.
- Pour and mix the liquid rubber components in the recipient, indications state there should be a 50-50 proportion. Pour it on the wax positive mold.
- To prevent leak, I designed and mount a little MDF frame.
It was not hard to demould; as you can see, wax and liquid rubber work easily together
- I left that until next day. But It's only necesary to let for 5 hours.
-Next day I obtained the negative rubber mold
Final rubber negative mold:
fa
Cast the Final Object
Using the negative rubber mold, using Hydro-Stone Super X, is a material that hardens in 30 minutes and activates with 1 part water to 5 parts HydroStone I made the final object.
The final object, my joint-vertex for fogcatcher, cuold be removed.
Concludings andRecomendations
- Take care to blend the materials, could appear bubbles. Make a homogeneous mix.
- Other solution for my object could be designed and assembly: use just one negative mold.