Jose Alegria - Fab Academy

Wildcard Week

Assignment

wHAT iS THE ASSIGNMENT ABOUT?

Design and produce something with a digital fabrication process (incorporating computer-aided design and manufacturing) not covered in another assignment, documenting the requirements that your assignment meets, and including everything necessary to reproduce it.

1^st Step: Defining the wildcard week process.

When I asked for different production methods for Molding and Casting, I was told there was one method we do not use while doing the assignment: Thermoforming. In our Fablab we were trying to make as extensive as possible every Group Assignment, so I was proposed to make a thermoforming procedure for molding, the problem was that to make that possible we had to overcome a couple of issues arising from the digital process of fabrication (3D Printing) of the first positive mold, the thermoforming requires to heat the product to make it soft, and this is not compatible with the materials we used for the 3D printers. So, I left this work for a later assignment and here we are.

2^nd Step: Setting up the parameters.

Thermoforming process requires the fabrication of a positive mold for which I decided to use 3D Printing. Due to the physical properties of the materials we can use for 3D printing in our lab, I settled with ABS (the material we had with the highest melting temperature). Then, I have to make a negative mold using the thermoforming procedure, for this I will be using a HIPS sheet to be used with our smallest thermoforming machine. Once this is done, we can cast anything with our mold. For this assignment, I tried casting with plaster.

So, this is the list of materials I will be using:

- Positive: ABS 3D Printing (Datasheet)

- Negative: Thermoforming in High Impact Polystyrene (HIPS) (Datasheet)

- Casting: Plaster

3^rd Step: Making the positive mold.

For this I used a design that was made by my coworkers using the Anahuac University Logo. This was made with ABS in our Sindoh 3D Wox Printer. The procedure is explained in the 06 - 3D Printing and Scanning Assignment.

4^th Step: Making the negative mold

This is the main step of the assignment. Once I 3D printed the positive mold, I started the process to create the negative mold by thermoforming. This is the procedure followed:

- Put the positive mold into the thermoforming machine.

- Fix the HIPs sheet into the upper compartment of the machine.

- Set the temperature for the thermoforming process above the HIPs melting temperature and below the ABS deforming temperature. The default temperature for HIPS was 160°C, but with this temperature the ABS would have melted, so I used a slightly lower temperature of 120°C and did not keep the HIPS sheet longer than strictly necessary.

- Start the machine to begin the heating process.

- Press the vacuum button to start the vacuum motor.

- Move the upper compartment down just to be set above the positive mold and slowly keep moving it down.

- Finish the procedure by releasing the HIPs sheet once it cooled down.

5^th Step: Casting.

Having already a negative mold, I continued to the casting step of the assignment by mixing plaster with water. The process is pretty straightforward and I am posting here a few photographs.

Conclussions

This assignment showed us that there are many ways to make a mold and cast anything into it. I tried to incorporate as many as possible digital fabrication processes, and as you could see, the human interaction was kept to a minimum. Maybe, there could be some way to mix and cast the plaster with a digital procedure. If so, that would be our next step to try and use.

Original Files

1. STL File

Nueval Checklist

- Documented how you made your creation

- Described problems and how you fixed them.

- Included your design files and hero shot of the result.

2022