As someone who works better with physical prototypes and visual cues, I would like to share the experiences from my own learning process, which could prove helpful to future users of extrusion-based clay printers. For this purpose, I developed a selection of 3D models testing the capacity and constraints of the 3D clay printer. It is now available at the Material-Archiv, located at ZHdK (Zurich University of the Arts). The digitisation of this collection is still in progress, as the Material-Archiv is establishing a new access platform due to launch in mid-2020.
But first things first. Let’s gain an overview of the digital fabrication workflow. To start with, one has to choose a type of manufacturing process. This implies knowledge of which type of material and machine – a robot, a CNC (computer numerical control) machine or a 3D printer – will be used. To perform its task, the machine requires data. The data is essentially the design, frequently a geometry created by CAD or AAD (computer- or algorithms-aided design) software. To read the data, the machine needs a specific programming language, which controls its functions. Therefore the design or drawing needs to be converted to another format via a CAM (computer-aided manufacturing) software. Usually called a “slicer”, the CAM produces a standardised language called G-Code, which instructs the motors of the machine, its arms and/or axis to move following a path with specific coordinates. In the case of a home-made robot, one can also write its own code using a programming language like Python.
Turning Drawings into Models
I had the opportunity to use a clay printer called Micro 8 from the Californian provider 3D Potter. It was helpful to read the manual and online instructions attentively to choose the right settings in order to produce objects. This involves being aware of the machine’s capacity and its restrictions (e.g. limits of movement, material properties, production dimensions, the formats used, etc.). After programming everything properly, I downloaded existing 3D models to quickly test the machine (you can find them on various free library platforms like sketchfab). But the real challenge started when I began to learn how to create a 3D model. The ITA ETHZ community recommended that I use the programme Rhino 6 and its plug-in* Grasshopper, because it can perform on two levels: 3D drawing and parametric design. Although you have to buy the main programme, there is a broad open-source library related to Grasshopper and other plug-ins. The most effective way to learn to use the software was to look at their official website. This offers a detailed online manual and video tutorials from basic introduction (such as: points, curves, surfaces, solids, mesh, vertices, edges, faces…) to complex structural drawings with parametric design.
Remembering all the tools and understanding their effects obviously takes considerable practice. However, if you find yourself overwhelmed or get stuck, a huge community of users fortunately exists, whose members regularly post tutorials and sometimes add their own plug-in to help you refine your geometries.
Once the design was completed, I needed to export the geometry – usually as a closed volume or a mesh structure – in a file format called STL (stereolithography). The STL format digitally transforms the shape in digital layers and can be read by the slicer. The slicer I used, Cura Ultimaker, enabled me to choose the settings. It can vary from rapid prototyping to objects in high resolution. After setting the right parameters, I sliced my object, exported the G-code to an SD card, and put the card in the machine’s computer. The transmission process differs according to how the computer reads the data. It can be connected to your computer via cables, WiFi or even bluetooth. After all this, magic can finally happen.
Turning Data into Objects
As I mentioned in my previous article (Beneath the Sea – a Multidisciplinary Journey. Part 1: Exploration), learning by doing was the best way for me to become familiar with my working environment. For instance, the collection of studies I decided to make had to follow a certain methodology. I needed to test the limits of the machine, of the material and of the geometries. Something very common in order to identify the restrictions of production is to design a model that presents technical benchmarks: overhang limit and curvature (see picture of studies below). You then shift settings to create a different printing rendition. Included in those settings are the ones from the machine-like nozzle size, travel speed, extrusion speed – or from the slicer, such as the layer height, travel-/extrusion speed and according to the CAM, other variables.
Once the digital part has been mastered, the focus moves to the material. As a natural material extracted from the earth and modified to a refined, homogeneous and malleable matter, clay represents various facets of modification processes. There are as many types of clay as there are different soils in the world. The three notable categories are earthenware, stoneware and porcelain.
Depending on the state of its plasticity – notably regulated by the water percentage contained in the mass – clay can be adapted to various techniques. For instance, you can throw it on the wheel, model it, or cast it in its liquid form. Showing a great aspect of sustainability, dried unburnt clay can always be recycled and serve one of many different functions. All these properties make it a perfect material to try new techniques without having to worry about waste.
Returning to the topic of digital fabrication, the machine I had at my disposal was an extrusion-based printer. It features a polycarbonate tube enclosing the clay, which is pushed out through the nozzle at the tip of the device. As mentioned before, clay is not just clay. In fact, no two types exhibit the same behaviour when squeezed under pressure. This is called a hygroscopic reaction: the clay particles change the distribution of water in the body of the clay, and can turn a soft clay into a solid one. To remedy this inconvenience, clay for the 3D Potter machine usually needs to be very soft. You can find different ways to moisturise your argil or porcelain. It is initially quite an adventure to understand how to make the perfect clay and then fill it in the tube. But with some practice, you will be able to prepare a homogeneous matter and load the cylinder without trapping air inside.
Turning Practice into Projects
So far, we have explored digital fabrication techniques and dived more deeply into the learning and transformation process involved in 3D printing with clay. But once we have acquired all this knowledge and practical experience, how can we implement techniques and interdisciplinary expertise in the context of a concrete project? In the next article I will focus on the purpose of my work and show a use case example.
*A plug-in is an external module to a main software. It adds complementary functions and cannot function individually.