Wrriten by Kitto
When starting with your CNC router —especially a GRBL-based machine like the Genmitsu series—you’ll come across a step in your CAM software that asks you to select the correct Post-Processor for your machine. If you’re not sure what that means, don’t worry—you’re not alone.
In this article, we’ll break down:
- What is a post-processor?
- Why does your CNC router need one?
- What post-processor should you choose for a Genmitsu CNC?
- G-code (mm) vs G-code (inch): which one’s right for you?
What is a Post-Processor?
A post-processor (or “post” for short) is a script or configuration that translates your toolpaths into G-code, the language your CNC router actually understands.
Most CAM software, like Fusion 360, VCarve, Carbide Create, or UGS Platform does not spit out raw G-code on its own—it needs to convert your design into code that matches your machine’s specific controller and capabilities.
Different CNC machines (like GRBL, Mach3, Marlin, Fanuc, etc.) all have slightly different “dialects” of G-code, so the post-processor ensures your output is compatible.
What Kind of Post-Processors Are There?
Here are a few common ones you’ll see in software like Fusion 360 or Vectric:
|
Post-Processor Name |
Typical Use Case |
|
GRBL |
Used for most entry-level desktop CNCs (like Genmitsu) |
|
Mach3 / Mach4 |
Industrial or custom-built CNCs with Windows control |
|
LinuxCNC / EMC2 |
Open-source CNC control systems |
|
Fanuc / Siemens |
Used in high-end industrial CNCs |
|
Marlin |
Used for 3D printers or hybrid CNCs (like MPCNC) |
Recommended Post-Processor for Genmitsu CNC routers
Genmitsu CNC routers are GRBL-based, so you should always choose a GRBL-compatible post-processor.
In most cases, you’ll see these options:
- G-code (mm) or G-code (inch)
- Sometimes labeled as: grbl_mm, grbl_inch, generic grbl, or Basic G-code (mm)
For Genmitsu, we recommend:
Use: G-code (mm) if you’re working in millimeters (most common internationally)
Use: G-code (inch) only if you’re in the U.S. and prefer inches
⚠️ Tip: If you’re not sure, always go with G-code (mm)—Genmitsu machines, by default, read metric G-code.
What Happens If You Choose the Wrong One?
Using the wrong post-processor can lead to:
- Incorrect scaling (e.g., your 10mm cut becomes 10 inches—yikes!)
- Unsupported commands that your machine doesn’t understand
- Missed tool changes, Z-axis issues, or bad homing behavior
That’s why selecting the right post-processor is critical for safe, accurate cuts.
Compatible Software with Genmitsu (GRBL) CNC Routers
Here are a few tools and the post-processor you should select:
|
Software |
Recommended Post for Genmitsu (GRBL) |
|
Fusion 360 |
grbl, gcode (mm) |
|
VCarve Desktop |
G-code (mm) (*.tap) |
|
Carbide Create |
Automatically GRBL-compatible |
|
LightBurn |
Uses GRBL or GRBL-M3 for laser module |
|
UGS / Candle |
Reads standard .nc or .gcode files |
Final Tips
- Stick with millimeter-based G-code unless your workflow is inch-based.
- If you’re unsure, check your machine’s controller board (Genmitsu = GRBL).
- Always run a simulation first before cutting real material.
- Save your most-used post-processor as default to avoid mistakes.
Choosing the right post-processor is like choosing the right translator for your machine. Without it, your CNC router doesn’t know how to “read” your file.
For Genmitsu GRBL-based CNC routers, use:
✅ G-code (mm) for metric-based workflows
✅ G-code (inch) for inch-based workflows
❌ Avoid using Mach3, Marlin, or Fanuc posts unless you know what you’re doing
With the correct post-processor, you’ll get clean, precise cuts and avoid a world of frustration. Happy carving!
