G-Code & Feedrates
Learn how to create G-Code and CAM using Inventor.
What is G-Code?
G-Code (also known as RS-274) is a numerical control programming language that provides instructions to CNC machines. It tells the machine exactly how to move, where to go, what speed to use, and when to turn tools on or off. Think of it as the "language" that CNC machines understand to create precise cuts and movements.
Why is G-Code Important?
G-Code is crucial for CNC operations because:
- Precision Control: It provides exact coordinates and movements for the machine
- Tool Management: Controls when to change tools, spindle speeds, and feed rates
- Safety: Includes commands for safe operation and emergency stops
- Repeatability: Ensures consistent results every time the program runs
- Flexibility: Allows for complex machining operations and custom toolpaths
How G-Code is Generated
While you can write G-Code manually, it's typically generated by CAM (Computer-Aided Manufacturing) software such as:
- Autodesk Inventor CAM
- SolidWorks CAM
- Fusion 360
These programs take your 3D model and machining parameters to automatically generate the G-Code instructions.
Learning G-Code Programming
Here's our tutorial that covers G-Code and CAM fundamentals using Inventor CAM:
Feedrate
This determines the rate at which material is fed to the bit. Generally, it is better to run the CNC at lower feeds because it does not have a proper fixture plate. If you run the CNC at higher feeds than recommended, there is a chance that you can damage the CNC and also break the expensive bits.
RPM
RPM (Rotations Per Minute) is the speed the spindle spins. We found that 24,000 RPM is generally a good speed for all materials that we cut in-house.
Cutting Feedrates
| Material | Bit | Feedrate | RPM | Coolant? |
|---|---|---|---|---|
| Lexan* | 4mm/6mm | 400 mm/min | 24000 | No |
| Aluminum | 6mm | 300 mm/min | 24000 | Yes |
| Wood* | 4mm | 300 mm/min | 24000 | No |
Drilling
| Material | Bit | Plunge Feedrate | RPM | Coolant? |
|---|---|---|---|---|
| Lexan* | 4mm | 45 mm/min | 24000 | No |
| Aluminum | 4mm | 30 mm/min | 24000 | Yes |
| Wood* | 4mm | 45 mm/min | 24000 | No |
Cutting lexan and wood releases heavy amount of small particles into the air around you. Please open the door/window and have proper ventilation prior to starting a lexan or wood cut on this machine.
These are units we found to work better for the machine, and are generally recommended to start with these. If you found better feeds and RPMs, I would recommend documenting them for future use. Last Updated: June 2026