How 3D Printers work

3D printing explained: what's all the fuss about?

IN DEPTH How to print your own action figure or body part

3D printing explained: what's all the fuss about?Complex prototyping is easy with the right 3D printing kit, such as the Replicator 2

It's rare that a truly new technology comes along, promising to revolutionise the world. Just as the printing press and spinning jenny empowered cottage industries with the ability to spread knowledge and manufacture goods, 3D printers promise to enable a next-generation industrial revolution of home-made and customised products.
In the industrial world, 3D printing is known as Additive Layer manufacturing, which should give you a hint as to how the process works. Thin layer after layer of material is built up, in a way that means a final fully-formed widget, hip bone, gun or part is produced.
It contrasts with traditional machine lathing, which has garnered the name Subtractive manufacturing, because material is removed to make a final part.

How to print in 3D

So how can you get started with 3D printing to become part of the revolution? The short and sweet answer is you'll need a 3D printer, suitable material for that printer, a 3D model to print and suitable software to do just that. Some of the big names in 3D printing are MakerBot, Up! Plus, Afinia and the most affordable RepRap design.
The MakerBot Replicator 2 is one of the best known 3D printers on the market, with a price tag of £1,800 / US$2,200 / AU$2,685, while 1kg (2.4lbs) of print filament costs around £52 / US$48 / AU$66. The MakerBot Replicator 2 has a print layer resolution of 0.1mm or 256dpi.
3D printing explained
The UP! Plus is another well known printer
In old-school print terms this sounds almost archaic, but this is more than fine enough to print perfectly smooth, curved objects that can be as large as 285 x 153 x 155mm (11.2 x 6 x 6.1 inches).
The Up! Plus 2 printer is a good contrast because it retails for US$1,650 (around £1,055 / AU$1,735) and has a 0.15mm or 166dpi resolution and maximum print volume of 140mm cubed.

Cheap 3D printers

In the popularity stakes, RepRap tends to win, largely because it's the cheapest brand on the market, with self-build kits starting at around £400 / US$600 (around AU$660).
It's rather dubiously known as the 3D printer that can print itself, which is really a half-truth, since only a number of connecting parts can be created this way. The rest are metal rods and electrical components, but it's a clever sell and most designs can be built entirely at home with basic DIY tools and materials.
What really makes the RepRap interesting is it's very much an open source design. This has enabled a number of alternative designs to spring into existence from the RepRap Mendel original.
3D printing explained
The classic RepRap Mendel 3D printer
For example the RepRap Wallace is a smaller lower-cost design, while theRepRap Prusa Mendel is a larger but easier and cheaper-to-build version.
A criticism of all these RepRap variants is the wedge-frame base design, so a popular alternative to this is the RepRap Prusa i3 that uses a more rigid box frame. While the MendelMax 2.0, which is going through its beta design phase, is gaining attention as the latest iteration of that popular RepRap design.
Common to all these printer types are print materials. To produce prints these lower-cost 3D printer units generally use acrylonitrile butadiene styrene (ABS), polylactic acid (PLA) or another member of the thermoplastic polymer family, usually supplied by the kilogram in a spools of 1.5mm thick wire, usually in a choice of different colours. As we've already said though, it's not cheap stuff.

Starting to print in 3D

Printing itself depends very much on the 3D printer you've chosen. Pre-built models such as the UP! Plus and MakerBot Replicator 2 are on the whole standalone and ready-to-go out of the box. The RepRap variants tend to be based on the Arduino USB control system, so need to be configured and run from a PC.
Typically getting a RepRap-based device up and running requires a good number of steps. These starting with installing the Arduino USB driver and development environment for the USB interface. Interfacing, communicating and supplying suitable 3D models to the RepRap requires a suite of tools. Many are built on the Python programming language, so you'll need the right build from, which is often version 2.7.
Communication tends to be handled by the Printrun package while preparing the final 3D model is done with Skeinforge or Slic3r. As with most external devices, the RepRap runs its own firmware, and again you have a wide choice, with Sprinter and Marlin being popular options.
3D printing explained
The base filament material used to squeeze out your designs
At this point you'd be ready to calibrate the system, load the plastic print filament and run a test print. You'll use Skeinforge to generate G-code that's sent to the printer by the Printrun Pronterface tool.
Once up to temperature, the 3D printer will slowly build up your object. On a first print you should carefully check for consistent output of the plastic and the positioning of the hotend print nib, and adjust the hotend, steppers and belts accordingly.
Plenty of sites such as or are happy to sell you pre-built 3D models to print. You'll likely want to create models from scratch though, so tools such as Blender and SketchUp are perfectly capable of enabling you to design models that can be converted to G-code ready for 3D printing.
3D scanners can help too, with the likes of the free ReconstructMe and KScan3D using the Kinect.

3D printing in the future

3D printing has it detractors. When a man fired a 3D printed gun, the shot reverberated around the world and focused the spotlight of regulators and governments firmly on 3D printing.
Even before this, 3D printing had attracted the ire of intellectual property lawyers, both in terms of patents surrounding 3D printing technology and the potential future infringements and effective piracy that 3D printers could enable. Disney wouldn't want you printing your own Mickey Mouse statues now, would it?
Even so, the future for 3D printing looks solid. It might currently be a niche, enthusiast or academic plaything, but as the material science advances the range, quality and durability of produced parts will only improve.
3D printing explained
The tweaked RepRap Prusa i3 box design
In the short term, expect the prices of kits such as the RepRap to drop. Online 3D repro services are already available, and will potentially come to your local shop parade soon enough. Once large manufacturers start releasing 3D printers, expect prices to drop and features to expand even more rapidly. Even now has an Additive Manufacturing products section.
Industrial manufacturers are already using specialist 3D printers for rapid prototyping and are eyeing up the technology to complement existing subtractive processes. One likely real-world use is for small-run bespoke luxury sports cars, where cost and construction speed are not an issue. More mundanely, Ford is already talking about printing spare parts for customers.
There's no doubt that both at home and in industry 3D printers will make their mark in the coming years. It's just a matter of when rather than if we're printing our own future.

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