CNC machines can be extremely powerful in enabling your creativity as a designer, artist, engineer, or even a hobbyist. Learning how to operate a CNC machine requires a great amount of effort, and no instruction can surpass the instructable Learn CNC The Hard Way by our fabulous DanVida. Although the "know how" aspect of CNC machining is super important, it's equally important to recognize CNC as "a mode of making", a tool that we can use or abuse in various ways, and a tool that empowers instead of dictates what we do.
This instructable - Learn CNC The Art Way - introduces a different perspective in approaching CNC. The aim is to demystify CNC, to explore what it means (instead of what it is) in the making process, and to inspire new ideas with extensive examples by practicing designers, artists, architects including a lot of the artists in residence at Pier9 Autodesk.
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Step 1: What It Is Vs. What It Means
CNC stands for Computer Numerical Control. CNC Machining is a process used in the manufacturing sector that involves the use of computers to control machine tools. CNC machining is a subtractive fabrication method, which starts with a solid block of material and use a cutter to remove the excess. It can be viewed as the opposite of 3d printing, which is an additive fabrication method.
Basically CNC machines translate computer data (a flat drawing or a 3d model) into sequences of location information for the machine cutting head in a 2d(in the case of a laser or waterjet cutter) or 3d(in the case of a CNC mill) space. If we don't put any materials in there, you basically just observe the machine "dancing" in space according to the path defined in your digital files. In other words, the machine head movement is "choreographed".
If we understand CNC on this basic level, we start to see the similarities between the additive(ex.3d printing) and the subtractive (ex. CNC machining) fabrication techniques. Both control a building head to move in space, but one removes material, the other adds material. If we can move a machine head in 2d space, when it subtracts material, it can cut or engrave like a laser cutter; when it adds material, it can be a drawing device or an embroidery machine. If we can move a machine head in 3d space, when it subtracts material it can be a mill; when it adds material, it can be a 3d printer; and it won't be hard to imagine the possibility of a additive/subtractive hybrid, like this one here.
Take our DMS machine for example. If we only define it as: a 5 axis machine that can cut out three dimensional forms in wood, plastics, etc, then we're already confining ourselves into thinking what it is we'll make in wood that can be cut on the machine. But if we define it as: a machine that moves in 3d space, doing whatever I don't know but to create forms, your scope of thinking suddenly gets expanded. For CNC learning, it's important to understand "what it means", not just "what it is".
Step 2: Surface Features
CNC milling create 3d forms, but the 3d solid isn't necessarily the focus of the end piece. 3D features make a surface interesting by introducing textiles/textures into it. A surface in space can block (ex. architectural tiles), reflect (ex. mirror), serve as a blank canvas(ex. projection mapping), or simply serve its own artistic purpose (ex. painting, mural). The following examples demonstrate CNC works that create interesting surface features.
1. 2d/3d sculptures based on flat data
2. Diffuse reflection on faceted surface
Faceted mirror by Anish Kapoor (see photo)
3. Projection Mapping
Projection Mapping on CNCed Surface by Gabriel Dunne
4. Architectural applications
Titles and blocks (see photos)
Step 3: Positive Shape Vs. Negative Shape
We can CNC positive shapes, as well as negative shapes. In other words, we can use CNC machine to create the end result directly, or we can use it as a step in a bigger process, using the CNCed form as an intermediate, or even sacrificial stage, followed by other (traditional) processes.
1. Positive Shapes:
2. Mold for forming sheet materials:
If you have a two-part mold that fit exactly, you can form a piece of sheet material (paper, cardboard, leather, fiberglass, etc.) in between. But you can also form sheet materials using only a male plug, by combining it with vacuum forming. Vacuum former and heat formable plastic sheets are used commonly in the special effect makeup industry to create armors out of a clay form. You can also do paper mache based on a machined form.
3. Mold for casting/injection molding:
Tectonic Horizons by Joshua Stein: CNC Machined Plaster Molds for Ceramic Slip Casting
Geometric black vase by Andy Brayman: CNC Machined Plaster Molds for Ceramic Slip Casting (see photo)
Mold for injection molding (see photo)
The possibilities in this direction is really endless since casting itself has so many variations (slip casting, sand casting, investment casting, etc.).
4. Sacrificial part:
Machined wax for investment casting (see photo)
Foam for fiberglass layup (see photo)
Step 4: 2D to 3D
When your material of choice is not suitable to 3d machining, or your project's size is too big to machine directly, you can use 2d CNC techniques (ex. lasercutter, waterjet cutter) to create profiles and stack them up to create the 3d form. The stacking/layering effect can also be incorporated into the overall aesthetics.
Brainwave Sofa by Unfold - a combination of 2d and 3d CNC machining
Step 5: Unconventional Materials
If we think about the "common" materials that can be milled on a CNC machine, we can deduce that materials with similar characteristics can be machined too.
We can machine metal on the HAAS mill, but that alone doesn't define where that metal comes from. It can come from stock or you can even cast it yourself if you have access to a foundry.
You can always create graphic patterns with different species, use reclaimed wood, and create all kinds of crazy shapes that are once only possible in the hands of experienced carvers/engravers. If you don't mind sweating you can even create your own fiberboard with chips and sawdust and whatever.
a few examples (see photos)
Synthetic materials have no shape, although you buy them in blocks or sheets. You can cast your own plastic/resin stocks and create various effects by coloring, layering, embedding other materials/objects, etc. Certain types of plastics can be re-melted and recycled, and that can be used to create melting effect and might add another layer of meaning to your works too.
To see what effects you can create with cast resin, check out works by Wonmin Park, Peter Alexander and Helen Pashgian. (see photos)
If we can machine wax then we can machine all sorts of wax-ish materials (soap, candle, chocolate, graphite, crayon, etc.).
It's impossible to list all the possibilities here. But I bet you can carve halloween pumpkins on a CNC machine.
Step 6: Performance Art / Choreography
Remember we talked about machine movement being "choreographed"? If we don't care what the machine head does and instead focus on its movement, the machine becomes a "dancer". Another aspect is sound, either playing with its natural sound or engineering it to play specific tones. Artist Kyle Machulis has done some really interesting works in this area.
Anti·gravity Object Modeling - the machine is not technically dancing but its movement is quite beautiful
Since it doesn't matter if the machine is cutting or not, if we can replace the cutting head with other stuff, for example, a light source, then we can probably do light graffiti (see photo) with it.
Last but not least:
Step 7: Randomness in a Controlled Process
CNC machining is a highly controlled process, thus allows repeatability for manufacturing. However, in art making, precision and control are not always what we look for. So how can we introduce chance and randomness into this controlled process?
"Chance was a crucial creative strategy for a wide number of artists associated with surrealism. It represented a release from the constraints of the rational world that had parallels with their interest in dreams."
This is very much about re-inventing your work flow. Four possibilities come to mind:
1. mess with the machine/G-code, so that its movement is somewhat random within a range.
2. mess with the digital model, for example the model is informed by changing data.
3. mess with the material, making custom materials that introduces unpredictability into the machining process.
4. mess with repeatability, machined part or mold designed to decay.
Step 8: Final Words
No matter how complicated a CNC machine might seem, it's important to remember that it's just a tool. As artists we take creative controls of the tools we have, rather than letting the tools dictate what we do. Just because we CAN do something doesn't mean we SHOULD.
Further inspirations: check out works by Ron Arad, Barry X Ball, Zaha Hadid, Stephen Jones, Anish Kapoor, Allan McCollum, Marc Newson, Roxy Paine and Greg Lynn.
I hope you feel inspired by this instructable, and happy CNCing!