Bed Mesh / ABL
Automatic bed leveling — probes the bed surface to create a mesh that compensates for unevenness during printing.
High priority
Printer-Specific
What It Is
Bed mesh leveling probes the print surface at a grid of points to map its topology. The firmware then compensates Z-height in real-time during printing, maintaining consistent first-layer height even on a warped or tilted bed.
What It Controls
- First layer consistency across the entire bed
- Adhesion uniformity
- First layer height accuracy
Why It Drifts
- Bed physically warps over time (thermal cycling)
- Bed mounting screws loosen
- Print surface replacement (different flatness)
- Frame flex or settling
How to Calibrate (Manual)
- Heat bed to printing temperature (thermal expansion affects flatness)
- Run
G29to probe the bed automatically - Save mesh with
M500 - Add
G29orM420 S1to start G-code to load mesh before each print
How the Auto-Tuner Calibrates It
- Already automatable via G-code
G29— the auto-tuner triggers probing and saves the result - Can schedule periodic re-probing based on print hours or temperature cycles
Related Anomalies
- Adhesion Failure — uneven bed causes poor first layer contact
- Warping — inconsistent first layer height contributes to warping
- Elephant Foot — nozzle too close in some areas from bad mesh