Bed Leveling Guide
The paper test, start to finish, for printers that level manually.
The paper test
1. Heat the bed and nozzle to printing temperature first — both expand slightly when hot, so leveling cold gives a slightly wrong result.
2. Home all axes, then move to the first leveling screw's corner.
3. Slide a standard sheet of paper between the nozzle and bed.
4. Adjust that corner's leveling screw until the paper drags with slight friction — snug enough to feel resistance, loose enough that it still slides.
5. Repeat at each remaining corner (and the center, on beds with a center screw).
6. Go back through all points a second time — adjusting one corner slightly tilts the others, so the first pass is never perfectly even.
Why "snug drag" and not "just barely touching"
Too loose (no resistance at all) usually means the nozzle is too far from the bed for good first-layer adhesion; too tight (paper won't move, or wrinkles/tears) means the nozzle is too close and will likely gouge the first layer or skip steps against the bed. The correct feel is friction you can clearly notice but that still lets the paper slide freely — it takes a few tries to calibrate what that feels like, and it's worth practicing on a bed you're not depending on for an immediate print.
Where mesh and automatic leveling fit in
Printers with a leveling sensor (inductive probe, strain-gauge load cells, or similar) still benefit from a reasonably level starting point — the sensor builds a height map to compensate for small variations, not to correct a bed that's wildly tilted to begin with. On printers with fully automatic first-layer calibration (many current-generation machines handle this without any manual screw adjustment at all), this manual process generally isn't needed; check your printer's own calibration routine first.