How does 3D printing actually work?

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How does 3D printing actually work?

In: Technology

Basically a thin layer of material is piped out and dries rapidly and then another thin layer is piped out on top of the previous one slowly building up a three dimensional structure. A computer is required to tell it what to pipe out and when.

It starts with a 3D computer model.
A slicer program slices it into layers.
The 3D printer has a print head that’s a lot like a glue gun, but instead of glue, it squirts hot plastic.
It prints one slice/layers at a time, one on top of another. Just as a stack of paper adds up to a thick book, a lot of thin layers of plastic add up to a 3D printed object.

I guess you are referring to Filament 3D printers. It is a technology called fused filament fabrication. Plastics that can melt and resolidify are shaped into a filament as building material. The filament is fed in the extruder (the printing head if you wish) where it is melted to make it flow and adhere to what it is deposited onto. Upon exiting the printing head, the plastic is cooled and resolidified so it will hold its shape and stick to what is has been put on.
Knowing that, building an object is achieved by dividing the object into a great number of horizontal layer that are approximately the width of the filament and each layer is filled one after the other, one on top of the other until the expected model is achieved.
For example a 3D cube is a stack of 2D squares glued on top of one another. So to get a cube you print a square on top of a square on top of a square etc… until the desired height is reached. cohesion within a layer and between layers are what makes it a 3d cube rather than a superposition of squares.

There are two major kinds of 3D Printing for home use.
There’s Fused Deposition Modeling (FDM) and Stereolithography (SLA) the latter is something also called Resin Printing.

In FDM, you take a spool of plastic wire, and push it through a hot nozzle to melt the wire. The nozzle is mounted on something that can move the nozzle left/right, front/back, and up/down.
It lays down a layer of melted plastic which cools and hardens. They then put a layer on top of that.

SLA has a bunch of liquid that turns solid when UV light is shined on it. They put it in a tank with a transparent bottom. Below that is a big UV light. Between the light is a LCD screen like on your monitor. It blocks the UV light from anywhere they don’t want hardened resin.
So they lower a plate only a tiny bit above the bottom, shine the light until it builds a layer, then move the lower plate up a bit and repeat.

Right now FDM is older technology so most of the kinks got worked out. It’s quite easy to make big things on it. But it relies on things physically moving alot so the quality isn’t as good.

SLA is newer. Big LCD screens that can block uv are expensive so the ones that cost about as much as FDM printers can only print small things. But since it’s just a screen blocking light, it can be very very detailed.

Imagine painting a shape a thick layer of paint, letting it dry, and then painting another layer on top of it. Soon enough you would have it lifting off the page and making a shape in 3D.

3D printing is basically the same thing, except it uses melted plastic instead of paint. You run the 3D model you want through special software that slices up the model into layers, and then one by one each of those layers are printed on top of each-other.

**Extra info:** Some printers (FDM) print like I described above while some print upside down, where instead of adding each new layer on top, the model is instead lifted out of a bin of liquid resin where each layer is added by a laser solidifying the next layer of resin beneath it (stereolithography). FDM is the more common method though.