How 3D printer work

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There is a lot of excitement building around what 3D printers can and might do. But how does a 3D printer work? It's actually not very complicated.

Here are the mechanics behind the most common consumer-level printers that extrude plastic. The first thing is: In goes filament, out comes hot and soft plastic.

Printing Filament

3D printer owners choses between two types of plastic: acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA). Some printers work with just one, other printers work with both. The plastic comes as strands of filament that are usually a standard 1.75 millimeters or 3 millimeters width.

ABS is chemical based and works at slightly higher temperature. PLA is derived from natural sources, such as corn or sugarcane. Its more rigid and glossy than ABS. Outside of 3D printing; it can be used to make compost able packaging.

Filament, which is usually stored on a spool attached to a 3D printer, can be expensive. It approximately costs $48 for 2.2 pounds of PLA, though PLA or ABS can be had for half the price on eBay. The company estimates one 2.2 pound spool of filament is enough to print 392 chess pieces.

The price is likely to drop as 3D printers become more common and filament is manufactured on a larger scale. One current way to drop the cost is to use filament extruder; you feed in cheaper plastic beads or recycled plastic, and out comes strings of filament.

Once you obtained the filament, it is fed into the 3D printer's print head. Generally, this is a boxy shape with a nozzle sticking out of it.

A gear pulls the piece of filament through the print head. Just before ti is extruded by the pointed nozzle, the filament passes through a heated tube and liquefies. The nozzle deposits it in ultra-fine lines generally about 0.1 mm across. The plastic solidifies quickly, sealing together layers.

ABS generally needs to be printed on a heated surface; otherwise , the bottom layer of plastic curls up. PLA can be printed on a surface that's strictly on room temperature.

3D Printer

Courtesy: MakerBot

Most printers have one print-head, which means objects are printed in one color, or the filament has to be switched out during the print job. Some printers, such as makerBot's newest, the Replicator 2X, have two print heads. This allows objects to be printed in two different colors. BotObjects has promised that mixes filaments to produce a full spectrum of color.

Layer by Layer

3D printing is additive manufacturing that means the plastic is built up one layer at a time.

The print surface – which is called the print bed – and print head work together to print in three dimensions. Usually, the print head is suspended on a gantry system. Two metal bars that run across the top of the Replicator support the print head. The print head can move back and forth along them. At the edge of the printer, the two metal bars connect to another two bars. This allows them to move forward and backward, and the print head to move in four directions altogether. The print bed moves up and down to add a third dimension.

Other 3D printers like RepRaps, the open source DIY printers that started the summer 3D printing trend, sometimes work slightly differently. The print bed may move up, down, forward and backward while the print head only moves side to side. Or there are more unusual systems, such as the DeltaMaker, where the print head moves in three dimensions.

Print jobs can take minutes, hours or days, depending on the size and density of an object.

Not Just Plastic!

Not all 3D printers are the same. Professional 3D printers are capable of printing higher quality objects with more diverse materials. At the shape-ways factory, where huge 3D printers output many objects at one, goods aren't limited to PLA and ABS. There's brass, ceramic steel and five types of plastic. Some of their machines rely on laser sintering, which uses lasers sintering, which uses lasers to fuse together particles of material. Some key laser sintering patents are set to expire next year, which could soon bring them to consumer printers.

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