Using Smoothie in grbl_mode

Smoothie's main job is to interpret G-code and to convert it into movement and actions.

Programs that generate Gcode are called CAM ( computer aided manufacturing ) software.

Unfortunately, they do not all mean the same thing by the same G-codes, and there are several different G-code formats.

Smoothie supports two different G-code "dialects" :

  • The "reprap" dialect, for 3D printing
  • The "grbl" dialect, for CNC milling

The "grbl" dialect is the closest to the "normal" Gcode standard ( NIST ), and is adequate and useful for CNC milling.

However, when the Reprap project created it's own interpreters early in the project, their developers ignored the "normal" Gcode standard and redefined some of the Gcodes to do other things, or kept their meaning but changed the way their parameters work.

Unfortunately, this has become such a widespread standard in 3D printing that it can not be changed anymore, and we are stuck with a bad format we have to understand if we want users to be able to use Smoothie for 3D printing.

Therefore, we support both formats.

The way you choose which format Smoothie will interpret the G-code you send to it as, is by changing the grbl_mode option.

If you set it to true

grbl_mode    true

Then Smoothie will interpret the G-code you send to it the same way GRBL or LinuxCNC does, as "normal" CNC G-code.

If however you set it to false :

grbl_mode    false

Then Smoothie will interpret the G-code you send to it the same way Reprap-type firmwares interpret it, as "3D printing" G-code.

CNC build

Smoothie has a special "CNC" build with some special CNC features and adaptations.

This special build has grbl_mode enabled ( set to "true" ) by default.

You can get the special CNC build pre-compiled at getting-smoothie or compile it yourself at compiling-smoothie


This page only mentions 3D printers and CNC mills. Lasers are neither.

Traditionally, Lasercutting software ( like laserweb or visicut ) have learned to talk to Smoothie in it's 3D printing mode.

However, more CNC oriented software can also be used to control lasers ( they are virtually similar to a CNC mill with a very thin tool and no Z axis ), this is the case for example of bcnc.

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