3D Printing Construction: What Can and Can't Be Printed Using Your Printer
In science fiction, 3D printers have been used to create everything from spaceships to food. In reality, the list is a little more restrictive.
Especially if we consider a typical home 3D printer, not a cutting edge model in an advanced laboratory.
So what exactly can or cannot your 3D printer create? Let’s find out.
Materials Supported in a 3D Printer
When talking about restrictions, the most important tend to be in terms of materials. For the most part, 3D printers work with plastic polymers. There are some technologies that can use other materials – for example, SLS printers can use metal powders – but polymers dominate the market.
And with good reason; plastic polymers are strong, light, and most importantly, cheap. They can be easily molded by heat or cured by UV light, enabling use in both FDM and stereolithography printers.
Filament options like PLA (Polylactic Acid), ABS (Acrylonitrile Butadiene Styrene), and PETG (Polyethylene Terephthalate Glycol) are all examples of plastic polymers used by an FDM 3D printer.
There are also specialized materials like Polycarbonate and Carbon Fiber that require extremely high extruder temperatures to use but result in very strong products.
Stereolithography printers use vats of liquid resins that solidify when exposed to UV light. Resin quality changes based on the cost, but all resins are ultimately plastic polymers.
It is in SLS printers that we get some real options. Owing to their unique technology, SLS printers can work with metals in powdered form, melting them into the required shapes with precise lasers.
But as SLS printers are found only in industrial settings, you are likely to be limited to plastics in your own prints.
Materials that cannot be used by a 3D Printer
The kind of materials that can or cannot be used by a 3D printer depends largely on the type of printer it is. Some materials, however, cannot be used by any type of printer.
Biological materials like living cells, or materials with microscopic details such as circuit boards, are impossible to print with any general 3D printer; there are some highly experimental printers that are being used to 3D print organs and even electronic components, but such printers aren’t exactly up for sale.
This extends to anything that is biologically derived, such as plant-based polymers like wood, fabrics, or paper.
FDM printers work by pushing material through a superheated nozzle, which melts them and deposits on the print bed. As you might imagine, this makes it difficult for this printer to work with materials that either do not melt easily or are prone to catching fire.
Wood, for example, is almost impossible to use with an FDM printer as the high temperatures burn it without melting it. There are some PLA derivatives that use wood grain to give a similar effect, and that is the closest you can get.
In a similar vein, inflammable materials like paper or cloth are unusable as well.
Then we have metals, which do not melt easily. Even gold or silver, the so-called ‘softer’ metals, are unusable with an FDM printer. Even if you do raise the temperatures that high, you will likely melt the extruder (and set fire to your print bed) before actually getting to use it.
Stereolithography is based on the solidification of certain liquid polymers interacting with UV radiation. As a result, these printers are the most restrictive in terms of materials, able to use only a limited selection of plastics.
Such polymers are called resins and are known for creating prints with smooth surfaces and detailed features.
While there is a range of resins with different densities and colors, stereolithography printers cannot work with anything else.
Selective Laser Sintering uses lasers to melt solid, powdered materials into layers. As lasers can achieve higher temperatures than extruders, this process can make use of many materials that wouldn’t be possible on an FDM printer.
Metals and metallic alloys are the best examples of this, giving 3D prints a level of strength and durability that cannot be matched by any other material.
But on the flip side, SLS printers cannot use any inflammable or ‘soft’ material, like fabrics, wood, paper, etc.
Design Limitations in 3D Printing
Even when you the correct materials, not every design can be 3D printed. The reason for this is simple: 3D printers work layer by layer. This makes it easy for them to make objects that are more or less cylindrical.
Of course, 3D printers can, and do print more complicated shapes, but the more you deviate from the norm, the harder it gets until you reach a point where a 3D printer just cannot layer it anymore.
This is a classic example of how a layer-based methodology can run into problems. If your model has large overhanging parts (a common example are hands or wings in a miniature), these parts will fall off as the bottom layers are not supported by anything.
You can overcome this issue with some workarounds. One solution is to change the orientation of the model (such as printing your miniature lying down) to minimize overhang.
Another, more preferable option as support material. Just print columns that connect the overhanging parts to the print bed, giving them a surface to rest on. The drawback with this approach is that it consumes a lot of extra material that ends up being wasted.
Small Area of Contact
Similar to overhangs, your 3D printer can find it difficult to print a model whose base barely touches the print bed. This is because the model will not adhere to the surface, sliding away even as the process is underway.
Once again, the solution is to build a platform underneath the object first, called a raft. The raft provides a mesh of support material that anchors the rest of the print to the spot.
In FDM printers, the nozzle extrudes molten materials. Even at the smallest diameter, an extruder cannot create paper-thin edges.
This poses a problem if your model sports sharp edges, as they will inadvertently end up as rounded and uneven.
Apart from changing your model to eliminate such features, you can also use a file or a knife to remove the excess material and manually create sharp edges after the item has been printed.
The Problem of Size
The actual working area of a 3D printer is quite small. If you go for a larger industrial 3D printer you can get more done, but for most 3D printing hobbyists size is going to be a limiting factor.
But what if you want to print something larger?
Print it in parts. You can always use glue or epoxy to stick them together.
Better yet, subdivide your larger models into logical components that can be assembled into a single, more robust piece. This way, whichever 3D printer model you use, you can print objects of any size.
As we have seen, only a small subset of possibilities cannot be 3D printed. It includes the obvious culprits – natural wood, paper, fabrics – and some difficult design configurations.
Frankly, there is no reason not to use plastic polymers; they are durable, easy to print, and cost-effective. And the design issues are easily worked around, either with support materials or smarter models.
The fact remains that 3D printers are one of the most versatile and flexible construction tools, capable of creating a surprisingly wide range of products in a home environment. You don’t really need to worry about limitations before buying a 3D printer of your own.