First-layer problems: what to check first
Record your printer, material, build plate and profile. Change one variable at a time and follow the model-specific instructions.
Why the first layer decides the rest of the print
The first layer anchors the entire object to the build plate. If it does not adhere, the part can shift or detach mid-print; if the nozzle sits too close, filament can be crushed and the path can clog. The target shape is a slightly flattened, continuous line without visible gaps or ridges between passes, and that target depends on your specific plate, surface and material rather than a single universal number.
Start from your printer’s own profile
Use the manufacturer’s recommended surface, material profile and cleaning routine for your exact build plate before changing anything else. Confirm the printer is plugged into a stable, grounded 120 V outlet and run its dedicated calibration routine if one exists rather than eyeballing the gap; a height value validated on one machine or one plate does not transfer automatically to another. Note the ambient room temperature during calibration too, since a cold garage or a print started right after opening a window can shift results even with an otherwise correct setup.
Read what the printed line is telling you
Visible gaps between lines or an overly rounded bead usually point to the nozzle sitting too far from the plate, though adhesion also depends on temperature, surface condition and flow rate. A flattened, translucent or ridged line can mean the nozzle is too close. Lifting corners can point to temperature, drafts or the material itself rather than the gap alone, so read the whole picture before adjusting. Photograph the result under consistent lighting so you can compare attempts over time rather than relying on memory.
Fix the plate and material before touching Z height
Confirm the plate is clean, the loaded material matches the active profile and the machine is correctly assembled before changing the first-layer height. If you recently swapped a nozzle, changed a plate or moved the printer, rerun the calibration routines your manufacturer recommends rather than layering new corrections on top of an already-shifted baseline.
Adjust in small, deliberate steps
Use your printer’s calibration pattern, review the result and make small corrections following the manufacturer’s manual rather than large jumps. Let each attempt finish enough of the pattern to judge continuity across the whole plate, not just the center, and record the plate, material and value you landed on so you are not repeating the same test blind. Resist the temptation to change two settings at once just because a first attempt at correction did not fully resolve the issue.
Know when the problem is not the first layer
If the first layer looks correct but corners lift later in the print, widen the investigation to temperature, cooling, orientation and warping rather than the plate gap. If the first layer looks correct but later layers are thin or missing, look at extrusion and the material profile instead. This checklist does not replace manufacturer support, and a defect that survives the official calibration procedure should be documented and reported rather than corrected repeatedly by trial and error.