A 3D printer is a device which converts your digital designs into tangible objects. This means that you can have a model of your design(made our of plastic) in a few hours without you having to do anything. All you have to do is design your object, select print settings and hit the print button! Most of the desktop 3D printers print using a process called FDM( Fused Deposition Molding) or FFF( Fused Filament Fabrication). What this means it that the 3D printer builds up your object/model layer by layer by fusing different layers of molten plastic. Just like a normal(2D) printer prints on paper and moves along 2 axis ( X and Y. Much like graphs), a 3D printer moves along 3 axis (X,Y and Z). Think of this as many of the same 2-D printed designs stacked one on top of the other! Similarly, a 3D printer draws the base of your object, moves up a bit and draws another layer of the same object on the layer underneath it!Thus forming your object layer by layer. This video by James from OhmEye explains the process very well.
So how to convert a design to a model once I have a 3D printer? It's simple! Once you are done designing your object/Model in a CAD software(Solidworks, AutoCAD,
SketchUp,ProE,etc), you have to export the design in a format called STL(Stereo Lithography).Don't worry about the big name - It's the same as exporting your Microsoft word file in the docx format! All "stl" does it that it describes your object's surface geometry in the form of triangles and vertices. Once you have exported your design file as an stl, you can close your CAD application and launch the software which you got with your 3D printer. There, you have to import the stl file of your object. You should be able to see it! In the software, you should be able to select infill(how dense you want your object to be) , At what resolution you want to print, at what speed you want to print and finally, with what material.
The 3D printer software establishes a connection between your computer and your 3D printer via USB/Serial. These
softwares take your design "stl" file as an input and accepts all your configurations of resolution,material,etc. After you've finalized your configuration, it exports something called GCODE. GCODE is instructions for your 3D printer- What coordinates to travel to, calculate and start extruding plastic out of the hotend. You can also monitor your 3D printer via these softwares as they display all the feedback which they receive from all the sensors on the printer.
I have worked on 3D Printing using FDM since 2011. Have developed a lot of different RepRaps, have Assembled an Ultimaker and a RapidBot 3.0 . If you want to build your own 3D Printer, you can chose a model from www.reprap.org and then go to it's GitHub link to find files and details. Although, repraps are great to learn 3D Printing, you will spend all your time in trying to make it work. And sometimes, they don't end up working and you spend a lot of money on continuously buying new parts. That's why my company Shark Industries is coming out with a DIY Low Cost 3D Printer which is really really well engineered so that anyone can put together a 3D Printer very easily which is guaranteed to work!
A few prints: