Build a 3D printer

A staple of much science fiction is the universal machine ­ whether called a cornucopia, replicator, foundry or something else, it’s a familiar concept: a machine that can make anything, and at its extreme, more copies of itself. While a truly universal machine, able to create complex circuitry as easily as a cup of tea or a new swimsuit is still a dream, the idea of 3D printing is far from fiction.

In fact, ‘rapid prototyping’ machines are nothing new –­ they’ve been used in industry for some years now, enabling design drawings to be turned into objects by laying down successive very thin layers of plastic in a process a little like inkjet printing. But these machines cost thousands of pounds, and are very complex ­ – certainly well out of the reach of the home or even small-business user.

But now a lot of that could be set to change, in large part due to work that’s been carried out over the past few years at the University of Bath. Scientists are creating a rapid prototyping device that’s not only a fraction of the cost of existing systems, but can be built and used without detailed specialist knowledge.

Rapid prototyping

The brainchild of Adrian Bowyer, Reprap is short for Replicating Rapid prototyper. The idea was first outlined in 2004, and the first Reprap built in May 2006 saw the ‘birth’ of the first child Reprap ­ – one for which as many of the parts as possible were made on the original machine. But before we look at Reprap in more detail, exactly what is rapid prototyping, and how does it work?

Although we mentioned inkjet printing in the introduction, it’s perhaps more accurate to think about plotters; a rapid prototyper is based around an extruder ­ – something like a glue gun, controlled by a computer –­ which is fed from a reel of plastic polymer. The polymer is heated and deposited on the surface below it. By moving the extruder head in the X and Y axes, it can create an outline, just like a plotter.

What makes things 3D is that the surface onto which the plastic is deposited can move up and down –­ the Z axis ­ – and so by lowering it slightly after the first layer, another can be laid down, and so on, building up a three-dimensional object.

The end result is a plastic version of the object, made using a polymer like polylactic acid (PLA) or acrylonitrile butadiene styrene (ABS). But that’s not necessarily the end of things ­ – not everything, for example, can really be made of plastic ­ – especially those exposed to high temperatures.

So in industrial or mechanical applications, the prototype that’s printed can then be used to create a mould, and an object then cast in metal or some or material. Since everything’s driven by computer, directly from drawings created in a Cad package, it can be far more accurate than making models and casting from them.

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