Knowledge
Practical LightBurn guides, settings, testing workflows and troubleshooting — written for real workshop use.
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9 articles
G-code Preflight Before You Trust a File
A preflight should establish units, distance mode, motion/laser state, bounds, feed/power context, unsupported commands and machine-specific assumptions before execution.
F and S: Feed Rate and Laser/Spindle Command Scale
F sets feed context for controlled moves; S sets spindle/laser command value within the controller scale. S is not automatically a percentage unless mapped against the configured maximum.
M3/M4/M5: Laser Output State in GRBL G-code
M3/M4 enable output modes and M5 disables output. For GRBL lasers, M4 is associated with dynamic laser power when supported/configured.
G90/G91: Absolute vs Incremental Distance Mode
G90 interprets axis values as absolute positions; G91 interprets them as increments from the current position. The same line can move somewhere entirely different under the other mode.
G20/G21: Inches vs Millimeters
G20 and G21 establish control units for following coordinates/feed values. A unit mismatch can turn a safe-looking file into a massively oversized move.
G2/G3 Arcs: I/J Centers, R Radius and Plane
G2/G3 describe clockwise/counter-clockwise arcs. Arc interpretation depends on active plane and whether center offsets (I/J) or radius (R) are used.
G0 and G1: Rapid vs Linear Feed Motion
G0 is rapid/travel motion; G1 is controlled linear feed motion. On laser jobs the important question is also whether laser output is active during the move.
G-code Modal State: Why One Line Depends on Earlier Lines
Many G-code words remain active until replaced: units, distance mode, motion mode, feed and spindle/laser state. Reading an isolated line without modal context can be misleading.
Console Window: When It Works and What It Is For
Understand what the LightBurn Console shows, why it is mainly for directly connected GCode lasers, and when not to expect it to work.