32-Bit Motion Control: Everything GRBL Does, Plus What It Can’t

Hitting GRBL’s limits on memory, axes, or processing power? Smoothieboard v2 offers 32-bit performance, 1MB RAM, 6-axis support, and text-file configuration. Keep the open-source values, ditch the 8-bit limitations. Used by CNC operators who outgrew GRBL.

Complex CNC part being machined with Smoothieboard

Upgrade from GRBL to Smoothieboard - $200

Shop Now - $200 at Robosprout

✅ 1MB RAM vs Limited 8-Bit Memory ✅ Native 6-Axis Support (vs GRBL’s 3-Axis Focus) ✅ Text-File Configuration - No Firmware Recompilation ✅ Still Open-Source + OSHWA Certified Hardware

You’ve Pushed GRBL as Far as It Can Go

You’re Hitting These Walls:

  • ❌ Out of Memory - Can’t load large G-code files from CAM
  • ❌ Processor Maxed - Complex curves cause stuttering/faceting
  • ❌ 3-Axis Limit - Need rotary or 5-axis but GRBL wasn’t designed for it
  • ❌ Firmware Recompile - Every config change needs recompile + reflash
  • ❌ Arc Tolerance Issues - Circles look like octagons
  • ❌ No Expansion - Arduino out of pins, can’t add features

Sound Familiar?

You’ve probably tried:

  • Splitting G-code files manually
  • Lowering CAM resolution to fit memory
  • Hacking multi-axis support into GRBL
  • Living with sub-optimal results

There’s a Better Way.

Everything GRBL Does, Without the Limitations

Technical Comparison:

Capability GRBL (8-bit) Smoothieboard v2 (32-bit)
Processor ATmega328 @ 16MHz STM32H745 dual-core @ 400MHz
Memory Limited 8-bit memory (2KB-32KB range) 1MB Flash + 1MB RAM
File Size ~1MB G-code max 30MB+ G-code files
Axes 3-axis (X,Y,Z) native 6-axis (X,Y,Z,A,B,C) native
Arc Quality Tolerance issues Smooth, accurate arcs
Configuration Recompile firmware Text-file editing
Connectivity USB only Ethernet + USB
Expansion GPIO Few pins left 63 GPIO via 8 headers
Lookahead Limited Advanced planning
Open Source Firmware only OSHWA HW+FW (FR000021)

What This Means in Practice:

  • Run complex 3D surfacing that chokes GRBL
  • Load huge CAM files without splitting
  • Add 4th/5th rotary axes natively
  • Change config in seconds not hours
  • Network your machine - no USB cable limits
  • Expand with sensors/tools using abundant GPIO

Easy Transition for GRBL Users

You Already Know Most of This:

  • ✅ Same G-Code - Standard RS274/NGC G-code
  • ✅ Familiar Commands - G0, G1, G2, G3, M3, M5, etc. all work
  • ✅ Compatible Software - bCNC, CNCjs, Universal G-Code Sender
  • ✅ Similar Workflow - Same CAM → controller → machine process

What’s Different (Better):

  • Config in Text File - Open config.txt, edit, save, reboot. No compiling.
  • More Options - More axes, more features, more expansion
  • Networking - Can use Ethernet (optional, USB still works)
  • Better Documentation - 250+ pages vs GRBL wiki

Migration Time:

  • Wiring: 2-4 hours (similar to GRBL Arduino wiring)
  • Configuration: 30-60 minutes (guided by docs)
  • Learning curve: Minimal if you know GRBL

GRBL to Smoothie Config Translator:

We provide a tool/guide to convert your GRBL $$ settings to Smoothie config.

Need More Than 3 Axes? Smoothie’s Got You

Native 6-Axis Support:

  • X, Y, Z - Primary linear axes (like GRBL)
  • A - Rotary around X (4th axis)
  • B - Rotary around Y (5th axis)
  • C - Rotary around Z (6th axis)

Use Cases:

  • 4-axis rotary engraving
  • 5-axis milling
  • Custom kinematics (6DOF robots, etc.)
  • Dual Y or dual Z setups (easy config)

In GRBL World:

Adding 4th axis requires:

  • Custom firmware builds
  • Hacking existing pins
  • Limited support
  • Wonky configuration

In Smoothie World:

Adding 4th axis:

delta_steps_per_mm     50      # Add A axis config
delta_max_rate         30000   # Set A axis speed

Done. Seriously.

Use Your Existing CNC Software

  • ✅ bCNC - Full support, popular choice
  • ✅ CNCjs - Web-based control
  • ✅ Universal G-Code Sender (UGS) - Java-based sender
  • ✅ Easel - Limited (web-based, GRBL-focused)
  • ✅ Any G-Code Sender - Standard G-code over USB/network
  • ✅ Smoopi - Raspberry Pi based touch interface created specifically for Smoothieboard (GitHub)

CAM Software Integration:

  • ✅ Fusion 360 - Post-processor available
  • ✅ Vectric (VCarve, Aspire) - Standard G-code output works
  • ✅ Estlcam - Compatible
  • ✅ FreCAD Path - Works great
  • ✅ FlatCAM - PCB milling support

You Don’t Need to Change Your Workflow:

Same CAM → same sender → better controller.

Still Open-Source, Just More Powerful

OSHWA Certified Open Hardware:

  • Certification: FR000021
  • License: GPLv3 (firmware) + CERN-OHL (hardware)
  • Design Files: All on GitHub
  • You Can: Build it, modify it, sell it, fix it
  • Community: 15 years of development, active contributors

Unlike Closed-Source Alternatives:

  • No vendor lock-in
  • No proprietary formats
  • No license fees
  • Community-driven development
  • Repairable hardware

For GRBL Users Who Value Open-Source:

You get the same open ethos, with hardware that matches the ambition of your projects.

Common Questions from GRBL Users

Q: Is Smoothie compatible with GRBL G-code? A: Yes. Standard G-code (RS274/NGC) works on both. If your CAM outputs GRBL G-code, it’ll work on Smoothie.

Q: Will my GRBL sender (bCNC, UGS) work with Smoothie? A: Yes. Most GRBL senders work fine with Smoothie. Some GRBL-specific features won’t work, but core functionality is there.

Q: Can I use Fusion 360 / VCarve / etc. with Smoothie? A: Absolutely. Any CAM that outputs G-code works. Fusion 360 even has Smoothie post-processors.

Q: Do I need to relearn everything? A: No. If you know GRBL, you know 90% of Smoothie. Main difference is text-file config instead of $$ commands.

**Q: What about \(settings from GRBL?** A: Smoothie uses `config.txt` instead. We have a migration guide showing GRBL\) → Smoothie config equivalents.

Q: Is Smoothie harder to set up than GRBL? A: No. Wiring is similar. Config is arguably easier (text file vs recompiling). Documentation is more extensive.

Q: Why not just use GRBL-32? A: GRBL-32 exists but is less mature/supported. Smoothie has 15 years of development, larger community, better documentation.

Q: Can I go back to GRBL if I don’t like it? A: Technically yes (wiring is similar), but GRBL users who switch to Smoothie don’t go back. You won’t want to give up the extra power.

Ready to Leave GRBL’s Limits Behind?

Smoothieboard v2 Prime - $200

What You Get:

  • STM32H745 dual-core 32-bit controller
  • 1MB Flash + 1MB RAM (30x more than GRBL)
  • Native 6-axis support
  • Ethernet + USB connectivity
  • 63 GPIO for expansion
  • Pre-flashed firmware
  • Comprehensive documentation

Resources for GRBL Migrants:

  • GRBL → Smoothie config migration guide
  • $$ settings translator
  • bCNC / UGS setup guide
  • Multi-axis configuration examples
  • Forum support for ex-GRBL users

Where to Buy:

Upgrade from GRBL to Professional 32-Bit Control

Upgrade from GRBL to Smoothieboard - $200

  • OSHWA Certified Open Hardware
  • 1MB RAM vs limited 8-bit memory
  • Native 6-Axis Support
  • Text-File Configuration
  • Auto-updates over Internet (can be disabled)

Smoothieboard v2 is OSHWA certified open hardware (FR000021). 15 years of proven performance. The logical upgrade path for GRBL users who need more power, axes, and flexibility.

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