WEEK 15: Wildcard Week

This week was about let the imagination fly.
We had to design and produce something with a digital fabrication process that we haven't done in any other assignment.
Some possibilities we had (with the facilities we have at FabLab Barcelona) are:

• Electrical discharge machining
• 5-axis machining
• Welding
• Vacuum forming
• Folding
• Food printing
• Biomaterials
• Textiles
• Composites (Fiber glass, Kevlar, Carbon fiber | Epoxi, Poliester)

Clay printing

This week we had the chance to test clay printing with a 5 axis robotic arm. It was very fun, but also really messy to work with the clay.
The robot we used was a ABB IRB 120:

We started with a chunk of dry clay, wich we had to break in smaller pieces and then hydrate it:

Then we had to knead the clay with the water until there were no clumps and the texture was the propper for printing

Once the mixture had the propper consistency, we had to fill the containers to attach to the robotic arm. The important thing in this step, is to avoid any air bubble in the mixture, because otherwise there will be gaps in the printing.

Then we attached the container to the robotic arm. It is connected to compressed air to push the clay, and it has a motor with a screw that propels the clay in the proper ammount.

Once we have the script of the model in grasshopper, which is basically a cloud of points in a certain order that tells the arm where to go, we plugged it to the robotic arm controller. Then after calibrating the tool and checking the origin, we were able to send the file.

After all, only the toughest part was remaining: to clean all the mess.

16 july update:

Creating the model and files:

The first task was to create the 3D model in Rhinoceros. The steps followed to create the object were the following:

Once we had the 3d model of the object we wanted to print, we had to prepare the files for the Robot Arm.
First of all, we need to install the Grasshopper plugin called Robots. It can be downloaded from this Github page. It is essential to also install robot libraries before using the plugin. They can be found on the project's github page.

Setting the workflow on Grasshopper:
We were given an introductory class on 3D printing with 6-Axis Arm robots back in February. The link to the class documentation is: https://fablabbcn-projects.gitlab.io/learning/fabacademy-local-docs/clubs/makeclub/roboticarm/. The class outlined a procedure to follow which is detailed below:

• Select your robot model using the "Load robot" component.

• Define your end effector (TCP, weight and geometry) using the "Create tool" component.

• Create a flat list of targets that define your tool path using the "Create target" component.

• Create a robot program connecting your list of targets and robot model to the "Create program" component.

• Preview the tool path using the "Simulation" component.

• Save the robot program to a file using the "Save program" component. If you're using a UR robot, you can also use the "Remote UR" component to stream the program through a network.

The toolpath obtained from the grasshopper program was placed on a USB stick which was then connected to the the robot's controller. From there, the file was loaded and the operation launched.

Result:

We made two trials. The first one was a failure, because the structure collapsed on itself within the first layers, probably because the design was not optimal for clay printing, and also because the clay was too liquid.

Then, we modified the geometry, to make just a straight resctangular prism. So, second trial started well:

But in the end, when moving it, it was still so soft that it collapsed again. Sadly, we didn't have more time with the robotic arm to make more tests.

Files:

Grasshopper script file
Rhino file

Conclusions:

Printing with clay and similar materials is something that as an architect I've been seeing a lot during the last three or four years, but I've never had the chance to actually do it.
It was simple as expected, and not so different from printing with any other material (apart from the mess of the clay), but I think it has a lot of applications specially in the architecture field, so I'm sure I'll keep learning and experimenting with it.

Making biomaterials

This week I decided to make some biomaterials.

I followed some recipes I found in https://materiom.org/
As I wanted to make sheets of bioplastics, I made a kind of a tray with acrylic cutting some edges and making a grid of three molds

Agar bioplastic (heated)

Link to recipe

Ingredients:

• Agar Agar - 4 grams
• Water - 420 ml
• Glycerol - 2.5 ml

Properties:

• Tensile Strength, Ultimate: 4.58 E-06 MPa
• Tensile Strength, Yield: 3.17 E-06 MPa
• Modulus of Elasticity (Young's): 5.42 E-05 MPa

Method:

1. We measure all the ingredients


2. Put the ingredients together in a pot. Stir until everything is disolved in the water.Put the pot in a stove and heat until 95ºC, stiring the whole time. Remove from the heat and keep stiring. Remove any froth from the top with a spoon.


3. Pour the liquid onto the mold.


4. Let it dry for 1-2 days.

Agar bioplastic (simmered)

Link to recipe

Ingredients:

• Agar Agar - 12 grams
• Water - 400 ml
• Glycerol - 18 grams

Method:

1. Measure all the ingredients


2. Mix all the ingredients together in a pot and stir until everithing is disolved. Heat the mixture to boiling point and simmer for 15 min, stiring constantly.


3. Take the excess of froth with a spoon, and make sure there are no clumps.
4. Put the mixture onto a surface or mold. Be careful because it solidifies fast once you pour it onto the mold, so do it at once and don't try to fix it afterwards (as I did), because it won't result flat (that's what happened to me).


5. After 4-5 hours, take it and let it dry hanging.

Methylcelullose bioplastic

Link to recipe

Ingredients:

• Methylcellulose - 31 grams
• Water - 600 mililiter
• Glycerol - 6.37 grams

Method:

1. Mix the water with the glycerin
2. Heat the mixture to boiling point and add the methylcellulose while sitiring, removing all the lumps.


3. Remove from the heat and take the froth and bubbles with a spoon.
4. Put the mixture onto a well leveled mold. In my case, as I had some leftovers, I tried a couple of molds from the molding and casting week to see what happens.


5. Let it cure for 10-15 days.

Conclusions:

I was so interested into experimenting with biomaterials. As we have such a big problem with plastics pollution nowadays, I think finding new materials made from ecological ingredients is the direction we have to take.
As I've never tried this before, It was a experimentation week for me, and as I love to cook, It had fun cooking all the recipes.
At this point, this is a non-finished assignment because some materials take several days to cure, so I'll update it when I can take them out of the mold and see the results, but the first impression is that they are quite easy to make and I think they can be a solution for some projects where we usually just think in regular plastics.

1 june 2021 update:

After letting the sheets dry, I took them from the tray. This is a comparison between the three sheets: (from left to right: agar heated, agar simmered, methylcellulose)

The agar agar heated sheet, resulted in a kind of almost transparent film that is so flexible:

The agar agar simmered was a failure, and the result was basically the same as the first day with the difference that it shrunk a lot.

The methylcellulose sheet resulted in a more strong and rigid sheet than the agar one, and also more transparent: