G-code is a language in which people tell computerized machine tools how to make something. The “how” is defined by instructions on where to move, how fast to move, and what path to move.
Layer by Layer
FDM printing can be thought of as 2D printing over and over again, layer by layer. This process is done by feeding the printer a .gcode file. The printer then reads this G-code by telling the printer how to move in the x-y direction for each layer, how much filament to feed, at what temperature to print, and how much the printer head should move in the Z-direction after completing that layer. The process is then repeated.
In order to get a G-code, one must create a “slice” of a 3D file. This is done by using a slicing program. There are free programs such as Cura, Slic3r, or the Makerbot program that comes with its printers (Makerbot actually uses .x3g instead of G-code). A paid program called Simplify3D is great for personalization of settings, but it can be a bit overwhelming at first. There are numerous basic settings for each material such as temperature, speed, and layer heights and there are advanced settings for infill, support, retraction and more. Tutorials, blogs, and our complete PLA and ABS profile settings guide on our website can help, but at the end of the day, trial and error is always required. This is because different printers using different hotends with different materials made by different manufacturers which can all lead to changes in settings.
Once happy with the settings chosen, it is a matter of exporting the part as a .gcode to whatever device is used for printing (SD card, Octoprint, etc)