Digital Fabrication, a Primer

Disponibile solo in inglese

Digital fabrication is a manufacturing process that uses the numerical values generated by a computer software as coordinates to control machines and create objects with an accuracy that would be hardly achievable by a human being.

Digital fabrication technologies have a series of advantages that make them a good match for producing physical data installations:

Figure 1: Exemplificatory abstraction of the main steps of a typical data driven (parametric) digital fabrication process

A typical digital fabrication workflow usually starts right after the designer has clearly established the looks, structure and functioning of the desired output on pen and paper, including the definition of more technical characteristics like the dimensions of all its various parts.

The first component of a typical digital fabrication workflow is to transform the sketches and drawings into a digital, mathematical, 3D model of all the components that need to be produced for the final output. In our cookbook, this phase will encompass things like:

These 3D modeling tasks are mostly performed through CAD software (CAD stands for Computer-Assisted Design), with occasional assistance of other types of software (for example, traditional 2D vector graphics software).

Once the 3D modeling phase is complete, this visually human-friendly design needs to be converted into a file with machine-readable instructions, so that the manufacturing machines can accurately and reliably craft the designed objects. This procedure is called G-Code generation. The G-Code file is the one that gets then imported into the machines. The exact steps required to create such file will depend greatly upon the type of machine you will use for the production. Generally speaking, digital fabrication machines can be divided into two categories: those for additive manufacturing, and those for subtractive manufacturing.

Additive and subtractive manufacturing

As the terms suggests, additive manufacturing refers to the fact that in such processes the material is added, layer by layers, until the final output is formed. The 3D printer is classic example of an additive manufacturing machine. The instructions contained in the G-Code provide the 3D printer with the coordinates defining the exact path that the extruder designs when it deposits each layer of material.

Subtractive manufacturing, on the other hand, does the opposite: the material is gradually removed so that the final output is carved out from the original material. Typical examples of subtractive manufacturing machines are the CNC milling machine - essentially a computer-controlled milling tool - and the laser-cutter.

They type of task and material you work with is what will determine which of the two manufacturing processes to adopt. Additive manufacturing is great to quickly produce complex shapes. However, while it works great for plastic objects, it generally less versatile with other materials. Additionally, unless you have access to a very expensive machine, size will also be a limitation, as you can only produce objects whose maximum size is that of the printer’s plane. Subtractive manufacturing, on the other hand, might not allow for very complex and creative shapes (again, unless you have access to a very powerful machine), but is more flexible in terms of materials. By choosing the right milling bit, the same machine will easily work with acrylic sheets/plexiglass, wood, metal, etc. Subtractive manufacturing is also usually a faster and cheaper process in comparison to additive manufacturing. All things considered, it is likely that a real-life project will integrate both processes to produce different components of the final output.

A few words on sustainability

Digital fabrication machines consume energy. Digital fabrication processes produce waste. Digital fabrication outputs are made of wood, plastic, metal and have an “afterlife” in terms of waste management. (By the way: so does printing newspapers, hosting website and storing stuff in data centers). You should be conscious about it., which in practice means several things. And, while we’re at it: please, don’t 3D print a giant plastic Buddha statue just because you can.

First, think about the whole lifespan of your product. How long will it be around for? Will it be impactful? Can I show it somewhere else after the installation is finished? Maybe someone else is interested in hosting it? Can I repurpose the material after I’m done? Try to optimize your product on the base of this.

Secondly, be mindful about the planning and digital modeling phases of your work, and don’t send something to the 3D printer or CNC until you are absolutely sure it will be produces as expected. When in the prototyping phase, first produce drawings and low-fi mock-ups with carton and paper. When you really need to print or mill the prototype, see if you can make it at a smaller scale that your actual output. Work near your machines and occasionally check on them, this way if something goes wrong in the fabrication process, you might be able to stop it in time before wasting more energy and material. Test the prototypes before producing the final output, or at least show it to as many people as you can (future audience, designers, more technical people, etc.). Whenever sending something to the CNC or the 3D printer, make sure it is optimized to use as less material (and time) as possible: make hollow shapes when 3D printing, fit as many shapes on the same sheet when milling, etc.
 Finally, you obviously need to source and discard your materials appropriately. Look up information about the materials you will use - there are many things that fall under the term “plastic”. Discard and recycle waste according to local rules. Save spare parts for future projects or give it away for free. Search for a near-by facility recycling 3D printer PLA objects to produce new filament: PLA is a thermoplastic material, meaning it can be used multiple times and there are several machines that can be purchased to convert plastic into 3D printing filament.