Molding and Casting

My experience

First step

For this week Stefany Casanova and me used the Modela MDX-20 3D Milling Machine, this machine still seems to have complications 😢 but it has served us well for the first part of this assignment. For our first test we used floral foam blocks, we were able to get them in a nearby store where they were offered as absorbent material for the plants. Thanks to its texture and size we could make a first simulation as if we were using a Wax, something interesting was that with this first test we started our exploration of some programs like ArtCAM and CNCjs. Next I show some of the design steps and then the milling with the foam. 💪

What's next?

Thanks to many videos that I was able to watch and follow the step by step I managed to have a first shape ready to mill. As I already knew a little FreeCAD I chose to do it in that program to know how the process would be in this type of modeling, which for sure is something different from what we have been working. After finishing with the 3d we use the ArtCAM program, this allows us to prepare our file to send it directly to the machine to work. Here I show the settings we used to achieve the first test. Thanks once again to Patricia because she already knew this program and with her advice I was able to learn it much faster. 💪

Fire test

After configuring ArtCAM we had to send the file to the CNCjs program because with this program our model can work. It is important to review the dimensions with which we are going to work, at first I found it a little confusing and it is likely that for beginners like me this process will be difficult, but everything is possible with a lot of practice. 💪 As a next step we sent the cut with a 1/8" milling cutter that I have thanks to my instructors in Barcelona and these were the results. 😃

First Conclusion

With this first test we realized that the height of our milling cutter and the maximum height of our machine in the Z axis did not allow us to put our material at its natural height, it was too stuck, we were afraid that the milling cutter would break when we used it since it was the only one we had, This is another reason why we used a foam block at the beginning because it would be very bad to break the cutter or damage the machine, so we cut the material and reduced the height, the bad thing about doing this is that we did not get the top face uniform, but it worked. Another point we noticed was that the router path seemed to make a parallel movement for each pass without us giving it that command, this worried us because something in our ArtCAM setup was going wrong. We reviewed the parameters and so as not to repeat the error we sought to change some parameters.
In the end it was not the problem of our parameters but of the machine. Thanks to the support of Eduardo Chamorro, my instructor in Barcelona, we managed to make some changes so that it would not go out of phase again and we succeeded. Thanks Eduardo. 😍

About design

As part of the joint work with "Patricia" we decided to make a single work file to take advantage of the only Wax we had, each one placed her design in the middle of the material, next I will show the photograph of the union of files, each one worked in a different software, at the moment of joining them we chose the Tinkercad program.

About the materials

We use a silicone Type 6 and a catalys, here some descriptions.

Silicone Rubber RTV SILIKAMOLD TYPE 6 + Catalyst

Medium/Low Viscosity
Color White
Working time 10 to 20 minutes.
Curing Time 4 - 8 hours in Summer, 8 - 12 hours in Winter.
Hardness/shore 30-A
Presentation Plastic Bottle Net Weight 1 kg + Catalyst 30 ml Dropper Bottle
Shelf Life 1 Year
Store covered, in a cool and dry place.
Exclusive and Imported Product by SILIKA MOLDES E INSUMOS EIRL.

(Source: https://silikamoldeseinsumos.pe/producto/caucho-de-silicona-rtv-tipo-6-1kg/)

About the tools

After getting support from other labs (which I will explain in this week's individual section), we were able to test our foundry phase implements. Below I show the tests we did with a weighting machine and some items that will help us to work with our silicone.



We carried out this whole process with the support of references from other former Fab Academy students and the advice of my instructor Josep Martí , who also gave us a lot of support with the online sessions. 🤩

First Test

As a group test we made a little mixture of the silicone with the catalyst in a small container, the idea was to dip some yases in the mass and then take them out to have the mold. I think that the test did not go so well, it was complicated to take them out and even the yases broke. Regarding the measurements, we used 2% of catalyst with respect to the amount of silicone. We also tried to make a test of gypsum with water but together with "Kelly" we realized that the mixture we tried to make did not work, we show the images here.

Second Conclusion

Thanks to the tests we were able to realize how important it is to have established measurements, both with the silicone and with the plaster we did repeated tests to test and get to know the material. My recommendation is to always look at the datasheet of any material you are using, for us it was important not to spoil the tests as we did not have much material but we still got great results, in the next section you will see everything we did in more detail.😃

My own design

To make my own design I chose once again the shape of a chakana, this is a millenary aboriginal symbol of the indigenous peoples of the central Andes in the territories where both the Inca culture (southern Colombia, Ecuador, Peru, western Bolivia, Chile and Argentina) and some pre-Inca cultures (Peru and Bolivia) developed. Also called Andean Cross, it is a recurrent symbol in the original cultures of the Andes and its shape is that of a square and staggered cross, with twelve points. This time I chose a new software to draw it, FUSION 360, I found it interesting to see that this program could be used to perform these molding and casting processes so below I share the steps of my first own design. 💪

First Conclusion

With this first design and simulator I understood that to design our molds it is important to take into account the shape of our figure, especially at the edges, as we see in the images above there are red faces on the inside which means that when working in the casting there will be problems to remove the material, which is why it is recommended to generate certain curves to facilitate the removal of the solid material.

Final Design

This whole process also helped me to understand the logic of the exercise, although this design is to make a casting, it will not help me to make our required mold, what I need is to make the design of the positive of my chakana, then I will show another design also made in FUSION 360.

Milling

After finalizing the design, taking into account all the requirements, we moved on to the milling stage. Thanks to Fab Lab ESAN Stefany and I successfully completed this stage with our wax. Below I show the images of the process and the result of both designs together. I want to give a special thanks to the ESAN instructors who also gave us technical and emotional support to be able to continue with the challenges ahead. Thank you very much!

Casting

Thanks to Fab Lab ESAN we successfully completed the milling phase of our wax. Below I show the images of the process and the result of both designs together.

Last attempt

Our first attempt to generate ice with our molds failed, we think it had to do with the refrigerator we have in the workshop as it does not freeze much so we did a new test but with another liquid, then I show you how it came out. 😍

Conclusion

I found it very interesting to do this whole process, it is the first time I work with silicone and the result has been very good. I am sure that I will use this process again for future works and continue exploring more materials that for time and few resources I could not continue doing it. 💪

Download the files here

Chakana