The first layer curls up, the print comes loose halfway through, or the nozzle drags a spaghetti mess across the bed. Bed adhesion problems are the most common failure on Ender, Creality, Prusa, and similar FDM printers, and almost all of them trace back to a short list of causes you can fix in an afternoon.
1. Clean the Build Surface
Fingerprint oil and leftover residue are the number one adhesion killer. Wipe the bed with 90 percent or higher isopropyl alcohol and a lint-free cloth, and do this before every print on smooth PEI or glass. For a textured PEI sheet, a wash with warm water and dish soap now and then removes oil that alcohol alone smears around. Avoid touching the print area afterward.
2. Re-Level the Bed
Even a bed that was level last month drifts. Heat the bed and nozzle to printing temperature first, since metal expands, then level using a sheet of paper or a feeler gauge at each corner and the center. You should feel slight drag on the paper. If your printer has automatic bed leveling, run the mesh routine again and confirm the probe is clean and tight.
3. Dial in the Z Offset
A nozzle too high leaves round, loose lines that never bond, while one too low squashes the plastic and blocks extrusion. Print a single-layer test square and look at it. Lines should be slightly flattened and fused together with no gaps. Lower the Z offset in small steps, around 0.02 mm at a time, until the square looks smooth and solid.
4. Check Bed and Nozzle Temperature
As a starting point, PLA typically sticks well with the bed at 55 to 65 C and PETG at 70 to 85 C, and ABS needs 95 to 110 C with an enclosure. Use the temperature range printed on your filament spool. A first layer printed a few degrees hotter than the rest often helps. Confirm the actual bed temperature with a thermometer if prints keep failing, as some beds read inaccurately.
5. Slow Down the First Layer
Printing the first layer at 20 to 30 mm/s and keeping the cooling fan off for it gives the plastic time to bond. Most slicers have a separate first layer speed and a setting to delay the fan until layer two or three. Raise first layer line width to around 120 percent for a stronger grip.
6. Use a Brim, Raft, or Adhesive
Tall or small-footprint parts need extra grip. Add a brim of 5 to 10 mm in the slicer for a wider contact area. For warping materials like ABS, a raft helps. A thin coat of glue stick, or a hairspray product made for 3D printing, adds tack on glass and some PEI surfaces. Wash it off periodically so it does not build up.
7. Dry or Replace the Filament
Old or damp filament extrudes unevenly, pops, and bonds badly. If your spool has sat open for months, dry it in a filament dryer or a low-temperature oven made for the purpose, following the temperature guidance for your material. Also check for a worn nozzle or partial clog if the first layer extrudes inconsistently.
When to Stop and Call Someone
If the bed is clean, level, at the right temperature, and the first layer test square still lifts, look at the surface itself. A PEI sheet with scratches, gouges, or a worn texture, or a glass plate with a coating that has worn off, can lose its grip for good. A new sheet is cheap compared with a new printer, but only replace it after the earlier steps are done.
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FAQ
Why does my print stick at first and then come loose later?
Usually it is warping. As the part cools, it shrinks and pulls its edges up. Raise the bed temperature slightly, add a brim, turn off drafts, and use an enclosure for materials like ABS.
What is the best bed temperature for PLA?
Most PLA prints well with the bed at about 55 to 65 C. Check your spool for the manufacturer's range and adjust from there.
Should I use glue stick on a PEI sheet?
It is not required for PLA on clean PEI, but a thin layer can help with PETG or large parts. Keep it thin and wash the plate periodically.
How do I know if my Z offset is right?
Print a single-layer square. The lines should be lightly squished and fused with no visible gaps and no ridges from over-squishing.