The real causes of poor bed adhesion — and how to fix each one
A print that won't stick — peeling corners, warping, or filament dragged around as spaghetti — is the most common beginner frustration in FDM printing. The good news is that bed adhesion almost always comes down to five things. Work through them in order and you'll fix the vast majority of failures.
This is the number-one cause. If the first layer is laid down too high, the lines stay round and barely touch the plate. You want the first layer slightly squished — laid as flat ribbons that fuse together. Re-level the bed and tune your Z-offset so a sheet of paper drags with light resistance under the nozzle. Lower the offset in small steps (0.02–0.05 mm) until the first layer looks smooth and merged, not stringy or gappy.
If one corner sticks and another lifts, your bed is uneven. Manually level all corners, or run your printer's auto-bed-leveling / mesh routine if it has a probe. A glass or PEI plate that has warped over time can also cause a stubborn low spot in the middle.
Skin oils and dust kill adhesion. Wipe the bed with isopropyl alcohol (90%+) before printing; for stubborn grease on glass, warm soapy water works well. Avoid touching the print area with bare fingers.
A cold bed won't grip. Use roughly 50–60 C for PLA, 70–85 C for PETG, and 95–110 C for ABS. If corners still curl, bump the bed a few degrees and raise the first-layer nozzle temperature slightly. Drafts cool the print and cause warping, so shield the printer from open windows and fans — an enclosure helps for ABS.
PLA loves PEI and glass; PETG sticks aggressively and may need glue stick as a release agent to avoid chipping the bed. Match the surface to the filament and the problem often disappears.
When something does fail, write down what you changed — bed temp, Z-offset, surface — and the result. After a few logged prints you'll know your printer's sweet spot and stop guessing.
Track your fixes in PrintLog →