Start with the failure pattern
A first layer that will not stick can come from several different causes that look similar at first glance. Watch the first few lines instead of judging only the failed part afterward.
- Filament stays round and barely touches the plate: the nozzle is probably too high, the bed mesh is not compensating correctly, or the plate is farther from the nozzle than expected.
- Filament is flattened but still peels or follows the nozzle: surface contamination, an unsuitable build surface, low bed heat, or aggressive first-layer motion is more likely.
- Only one side or corner fails: think bed mesh, gantry/bed geometry, local contamination, or an uneven plate before changing global flow.
- The center is good but edges lift later: move from first-layer contact into warping, cooling, drafts, and geometry rather than forcing the nozzle closer.
1. Clean the build surface before recalibrating anything
Finger oils and residue can create a first-layer problem that looks exactly like bad Z offset. Clean the plate using the method recommended for that surface, let it dry, and avoid touching the print area. If adhesion returns after cleaning, do not compensate by making the nozzle lower.
2. Check Z offset by looking at line shape
The correct Z offset puts the nozzle close enough for adjacent first-layer lines to join without the nozzle plowing through them. If there are gaps between lines, weak contact, or round strands, use How Do I Calibrate Z Offset?. If the surface is ridged, scraped, translucent, or the nozzle drags through deposited plastic, the nozzle may already be too close.
3. Make sure bed mesh compensation is actually in the workflow
A bed mesh can compensate for measured height variation, but only when the printer's normal workflow loads or uses the intended mesh. If one region behaves differently from another, use Bed Mesh and Z Offset Workflow or Why Is My Bed Mesh Not Working? before repeatedly changing Z offset.
4. Separate bed temperature from nozzle temperature
Bed temperature supports first-layer contact and slows early cooling; nozzle temperature controls melt behavior. Use the filament and build-plate manufacturer's limits as the first constraint. If the line shape is already correct but the material releases too easily, test a modest bed-temperature change while keeping Z offset and flow fixed.
5. Slow the first layer only when contact is otherwise correct
High first-layer speed can pull on plastic before it has established stable contact. Reducing first-layer speed can help, but it will not fix a dirty plate or a nozzle that is visibly too high. Keep the diagnostic order intact so a motion change does not hide a calibration error.
6. Check first-layer flow only after height is credible
Flow changes alter how much plastic is deposited, while Z offset changes the physical gap. They can imitate each other. Do not use large flow changes to compensate for an obviously incorrect nozzle height. Once line contact is correct, small flow corrections can be evaluated with a consistent single-layer pattern.
Fast decision path
- Round separated strands: check Z offset and mesh.
- Flattened strands that still peel: clean the plate, confirm surface/material compatibility, then check bed heat.
- One area fails: inspect mesh, geometry, or local contamination.
- Whole first layer sticks but corners curl later: move to warping/cooling diagnosis.
- Nozzle scrapes or creates ridges: stop lowering Z; inspect a too-close first layer.
Verify the fix with one repeatable first-layer pattern
Use the same small test after each change. The goal is continuous lines that touch cleanly, remain attached during direction changes, and do not show deep nozzle ridges. Once the pattern is repeatable, save the known-good Z/mesh/profile state before returning to a full print.