3D printers are complex devices that can “print” physical objects based on 3D computer models by laying down hundreds of thin layers of a material one on top of another. As these layers of material slowly build up, the object begins to take shape one slice at a time until it is completely formed. 3D printers come in many varieties that use different techniques and different materials. While typical consumer 3D printers use FDM (fused deposition modeling) to print with a variety of plastic filaments, more specialized 3D printers can print with other materials like metals, concrete, food, and even living cells.
Fused Deposition Modeling
There are several different methods of 3D printing, but the most widely used is a process known as Fused Deposition Modeling (FDM). FDM printers begin by melting down a spool of modelling material known as filament. This filament can come in a wide array of materials, but is most commonly made of a thermoplastic known as PLA. Once the filament is heated to its melting point, it is then extruded through a nozzle (like a hot glue gun) and slowly lays down layer after layer to build up a 3D object.
An Introduction to 3D Printing
Want more information about 3D printing? Watch this short 45 minute video for an introduction to processes, materials, and potential of 3D printing. Additional print resources are also available below the video.
3D Model – the representation of a physical object using a collection of points and mathematical equations in a virtual 3D space, typically created using CAD software.
CAD (Computer Aided Design) – CAD software allows you to design a 3D object using your computer. TinkerCAD is an example of a free online CAD software.
Extrude– the act of placing the 3D printing material on the build platform, normally by heating thermoplastic to a liquid state and pushing it through a small nozzle.
Extruder– a group of 3D printer parts which handles feeding and extruding of the printing material. Extruders consist of two assemblies: a cold end to pull and feed the thermoplastic from the spool, and a hot end that melts and extrudes the thermoplastic.
FDM (Fused Deposition Modeling)– a common form of 3D printing where a material, typically plastic, is melted and then extruded into layers that then fuse together (see above).
Infill– the interior structure of a 3D printed model which determines how solid the final object is. In most cases the infill of a 3D printed model can be adjusted anywhere from 5% (almost hollow) to 100% (completely solid). More infill means the final object is sturdier but it also requires a lot more material.
Nozzle– the part of the hot end of an extruder that deposits the melted plastic material.
PLA (Polylactic Acid)– a renewable bio-plastic (made from corn) commonly used for 3D printers.
Printbed– the surface of the 3D printer on which the 3D printed part is formed.
Slicer– a software program that is required to convert a digital 3D model into a format that a 3D printer can read and recreate. This software takes a 3D model and slices it into 2D layers that can then be printed. Slicer software also tells the motors of a 3D printer how to move in order to accurately trace out the shape of each layer. Different printer manufacturers use different slicer programs, but the library's MakerBot printers use the MakerBot Print slicing software.
STL– the most commonly used file format for 3D printing. This type of file describes the surface geometry of a 3D object. OBJ, PLY, and THING are some other 3D printing file formats.
Support Material – additional material that is printed alongside your model in order to support steep angles, overhangs, hollow areas, or gaps in the final model. Supports are usually required for any angle over 45º. In the image below the angles of the "Y" are not steep enough to require supports while the 90º angles of the "H" and "T" do. This support material can later be broken off, cut away, or melted to reveal the final design.