What is a GCODE file?

A GCODE file is a plain text file that contains instructions for controlling computerized machine tools and 3D printers; G-code, or “Geometric Code,” is a language used to control movements and actions of CNC (Computer Numerical Control) machines; CNC machines include milling machines, lathes, routers and 3D printers.

G-code commands are written in specific syntax typically consisting of letters and numbers; each command instructs machine to perform specific action such as moving tool to particular position, changing tool or adjusting speed.

G-code is often generated by CAM (Computer-Aided Manufacturing) software; CAM software takes 3D model or 2D design and generates corresponding toolpaths and G-code instructions; the G-code file is then loaded into CNC machine or 3D printer for execution.

G-code files typically have “.nc” or “.gcode” file extension for example, “program.nc” or “print.gcode.”

GCODE File Structure:

GCODE files are plain text files with each line containing specific command; these commands range from controlling movement of machine to adjusting temperature, speed and other parameters crucial for fabrication of an object.

The syntax of GCODE involves combination of letters and numbers; each representing distinct action or parameter; common commands include G0 and G1 for movement, M3 and M5 for spindle control, and S and F for speed and feed rate adjustments respectively.

GCODE Generation:

Slicing software such as Simplify3D and Slic3r, translates Computer-Aided Design (CAD) drawings into GCODE; CAD software is used to create 3D models, which are then exported in formats like STL; the slicing software takes these models and generates GCODE file specifying details such as layer height, printing speed, and temperature settings.

GCODE Example

Here is simple example of G-code for moving CNC machine:

G0 X10 Y5      ; Rapid move to position X=10, Y=5
G1 Z2 F500     ; Linear move to Z=2 at feed rate of 500 units/minute
M3 S1000       ; Start spindle at 1000 RPM
G2 X20 Y10 I2 J0   ; Clockwise circular interpolation
G0 Z5          ; Rapid move to Z=5
M5             ; Stop spindle

How to open a GCODE file?

To open a G-code file you can use different types of software depending on your needs.

If you generated G-code for 3D printer; you can open it using software that came with your 3D printer or dedicated slicing software; examples include PrusaSlicer, Cura, Simplify3D, MatterControl or Repetier-Host; these programs often have user-friendly interface that allows you to load and visualize G-code.

GCODE files are plain text so you can open them with any text editor; common text editors include Notepad (on Windows), TextEdit (on macOS), or Gedit (on Linux); simply right-click on the G-code file, choose “Open with,” and select a text editor.