Skip to content

10. Molding and casting

Maybe this week is the funniest week of the FabAcademy until today.

Group assigment - Data Sheet

As a remote student I am alone in the FabLab, so I have to do this part individually. *

First of all, as always, you need to prepare what are you going to do this week, and among these tasks, I will need information about the silicone I want to use.

In this case, I want to try with food silicone, because I have never used it before, specifically Easyl 940-FDA.

- Hardness: Shore A25
- Max Tº: 220º
- Proportion: 1A=1B
- Curing time: 3-5h
- Handling time: 30 min
- Unmold time: 24h

If you want more information and the Data Sheet of this material you will find it here:

Designing 3D model

I want to make chocolate nautilus, so I research design principles of how to do it and I proceeded.

Then I generate a mold based on the wax block I used for milling the mold.

After milling, as I will show you later, this mold was not good because I did 90º box without unmolding angles. In addiction there was a problem with the geometry.

So I tried with a simple one by the moment. A chocolate peg-top because in FabAcademy is allowed to play with food!!

Here is the process of this new piece.

The new mold again

And as you can see I fixed the mistakes, with better angles in the corners.

Finally you can download here the model of my model:

Learning RhinoCam

I usually use Vcarve program for milling in the milling cutting machine but this is FabAcademy so I would like to learn another program so I try with RhinoCam, it is a plugin for Rhinoceros.

When you import a .stl in Rhino open the plugin and follow the steps.

We will need to generate 2 paths Horizontal Rouging and Parallel Finishin.

Horizontal Rouging to mill big areas

I - Select the working Area
II - Select the correct Tool (universal 3mm tool)
III - Select the speed of movements (1000 mm/min)
IV - Select the high for the z axes movements
V - Select depth of each step in the block
VI - Select how will be the roughing of the mill

Parallel Finishing to define the piece. Same configuration with some changes

II - Select the correct Tool (Ball 2mm tool)
III - Select the speed of movements (4000 mm/min)
VI - Select how will be the roughing of the mill

Here are the results of the previous model but the configuration is the same for the other piece.

Milling the Mold

First you will need to prepare the wax block fixing with double-sided tape. The machine I am using is the same as assignment 8 a Roland Mdx40A.

Second step is to calibrate the machine XY and Z Axis.

These are the mills i am going to use for both paths.

Here we can see the process and how you have to pause the machine to clean the wax.

Finally after two paths, roughing and finishing, you will have a piece like this.

Generating the Mold

Now it is the moment to use the silicone I have described before.

But first I need to put a slim layer of unmolding, in this case edible petroleum jelly

Finally we pour the mixture into the mold

Final Piece

These is the final mold. As you can see it has 2 parts, a negative and a positive side.

Do not FORGET TO CLEAN it few times generously with water and soap. And just meld chocolate, pour it with a syringe and wait cold it down in the fridge.

Finally I have this piece and it works!! the next time I will be the upper part thicker because it is a little bit narrow for this function.

But it is a perfect toy to play with the food!!!

I have tried with another materials as water but the result was a disaster!! It´s ti difficult to catch ice!!

Licencia de Creative Commons
Este obra está bajo una licencia de Creative Commons Reconocimiento-NoComercial-CompartirIgual 4.0 Internacional.