G-code output

What Beam Bench emits when a job runs. How to read it, save it, and feed it to a machine outside Beam Bench.

When you run a job (or click Save GCode in Laser Control), Beam Bench emits standard G-code that GRBL-based controllers understand. This page describes the high-level structure and how to use the output.

What it contains

A Beam Bench G-code file is structured as:

Job header (if configured in the machine profile), your custom prefix commands.
Coordinate setup: typically G21 (mm), G90 (absolute), G94 (units per minute).
Per-layer / per-segment commands:
- Rapid moves (G0) with the laser off.
- Cutting / engraving moves (G1) with S<power> for power and the layer's feed rate.
- Laser on / off as needed (M3 or M4 for constant or dynamic power, M5 for off).
- Air assist commands if configured.
Job footer (if configured), your custom suffix commands.

The exact dialect depends on:

The machine profile's Output Policy settings (see Device Settings → Profiles):
- Constant Power (M3) vs dynamic (M4).
- Emit S on Every G1: repeat power per line vs once at start.
- S-value Max: the controller's max S value (usually 1000 or 255).
- Use G0 for Overscan: overscan via rapids vs feed.

How to get the file

GUI: Laser Control → Save GCode opens a save dialog when a machine is connected, or use Laser Tools → Save Machine Files after preview is current.
CLI: beambench-cli export gcode /abs/path/project.lzrproj /abs/path/out.gcode (positional input and output).

Saving G-code through the menu or CLI does not require a connected machine. Useful for:

Sending the file to a machine on a different computer.
Feeding GRBL via a different sender or bridge.
Inspecting the output for debugging.

Reading the output

For GRBL specifically, the relevant codes are:

Code	Meaning
`G0 X Y F`	Rapid move to X, Y at feed rate F. Laser off.
`G1 X Y S F`	Linear move with laser on at power S, feed rate F.
`M3 S`	Spindle / laser on, constant power mode.
`M4 S`	Spindle / laser on, dynamic power mode (varies with feed).
`M5`	Spindle / laser off.
`M7 / M8 / M9`	Coolant / air assist on / off (varies by config).
`S<n>`	Power, scaled to S-value Max.
`F<n>`	Feed rate (mm/min in default GRBL config).
`G21`	Set units to millimeters.
`G90`	Absolute positioning.
`G91`	Relative positioning.
`G92 X Y`	Set current position to (X, Y), used for Job Origin.

Edge cases

The same Beam Bench project can produce different G-code with different machine profiles (different Output Policy, different S-value Max, different Air commands). The output is profile-specific.
The Job Header and Job Footer in the profile are emitted verbatim. They can contain machine-specific setup (homing, coordinate system selection, etc.).
Beam Bench's planner outputs lines and points the optimizer produced. Hand-editing the output is possible but fragile, small changes can confuse subsequent moves.

Laser Control: Save GCode button
Device Settings dialog: Output Policy fields
GRBL essentials
Console panel: manual G-code testing