First layer not sticking? 9 fixes for FDM 3D printers

First-layer failures are the single most common 3D printing problem, and thankfully the easiest to fix. This guide walks the 9 fixes in order from cheapest to most invasive — in practice, the first three solve about 80% of cases on Bambu, Prusa, Creality and any other FDM machine.

What a healthy first layer looks like

Before you fix anything, calibrate what "good" looks like. Print any standard first-layer calibration square (most slicers ship one) and inspect:

• Lines are touching with no gaps between them. Gaps mean the nozzle is too high.
• Lines are flat, not round. Round lines mean the nozzle is too high. Visible nozzle drag marks mean it's too low.
• The print is stuck. You should not be able to flick the calibration square off with a fingernail. If you can, keep going through this list.
• No translucent patches. Translucent = under-extruded = too high or under-flowing.
• No "ploughed field" texture. Visible furrows in the plate finish mean the nozzle is gouging into the sheet.

1. Clean the build plate (the #1 fix)

Skin oils from one fingerprint are enough to break adhesion. A "brand new" sheet still has residue from packaging and manufacturing. Clean before every multi-day print and at the first sign of trouble.

1. Remove the sheet from the printer. Cleaning it in place pushes oils around.
2. Wash with warm water and unscented dish soap. Dish soap actually dissolves oils; isopropyl alcohol mostly redistributes them. (IPA is fine as a maintenance wipe after a soap wash.)
3. Rinse thoroughly — soap residue also blocks adhesion.
4. Dry with a clean paper towel (microfiber sheds lint). From here on, only touch the sheet by the edges.
5. For PEI: a final wipe with 90%+ IPA after the soap wash gets you the cleanest possible surface.

2. Set the Z-offset correctly

Z-offset (also called "live Z" on Prusa and "Z calibration" on Bambu) is the height of the nozzle above the bed for the first layer. Too high → lines don't stick. Too low → nozzle gouges the sheet and back-pressures the hotend.

The paper test (works on any printer)

1. Heat the bed to the temperature you'll print at (a cold bed is shorter than a hot bed by a few hundredths of a millimetre — enough to matter).
2. Home the printer and disable steppers so you can move the head by hand.
3. Slide a sheet of standard 80 gsm paper under the nozzle at the bed's centre.
4. Lower the nozzle until you feel slight drag on the paper as you slide it but the paper still moves freely. That's your zero.
5. Save the offset and start a first-layer test print. Adjust in 0.025 mm increments while it's printing — live-Z on Prusa/Bambu lets you do this on the fly.

3. Match bed temperature to filament

Bed temperature controls how well the plastic bonds to the sheet. Too cold and the first layer never grabs; too hot and you get elephant's foot (the bottom layers squish out wider than the rest of the print).

4. Slow down the first layer

The first layer is the one place where slow always beats fast. Modern slicer defaults aren't always conservative:

• Default to 20 mm/s first-layer speed regardless of what the slicer suggests.
• Use a first-layer flow ratio of 1.0–1.05 — a small over-extrusion helps adhesion.
• Increase first-layer line width to 0.5 mm on a 0.4 nozzle (or 125% of nozzle diameter generally).
• Set first-layer height to 0.2 mm minimum even if the rest of the print uses 0.12 mm. Thicker first layers fill in bed irregularities.

5. Re-run bed leveling and bed mesh

Beds move — thermal expansion, transport, even a hard print failure can tilt one corner. Run a mesh-bed-leveling pass any time you notice the first layer is good on one half of the plate and bad on the other.

• Bambu: auto-calibrates every print, but you can force a fresh mesh from Device → Cal → Mesh.
• Prusa MK4/CORE One: run Calibration → First-layer Calibration if Live Adjust hits its limits.
• Klipper machines: rerun BED_MESH_CALIBRATE from the macros menu.
• Manual-tram bedslingers (Ender 3 v1, Voron 0): tram corners cold with a feeler, then re-do it hot.

6. Eliminate environmental factors

• Drafts kill PLA and PETG bed adhesion. A window open across the room is enough to drop the bed temperature locally. Close doors, move the printer away from HVAC vents, or enclose it.
• Cold ambient (under ~18 °C) stretches first-layer adhesion time on every filament. Warm the room or pre-heat the bed for 10 minutes before starting.
• Direct sunlight on the build plate creates a hot spot the bed sensor can't see. Shade the printer.

7. Add a brim (or raft, as a last resort)

A brim is a single-layer skirt that attaches to the print and dramatically increases the bed-contact area. It's the difference between a 30 cm² first layer and a 15 cm² one for tall, narrow prints.

8. Use the right adhesion aid for your build surface

Sheet surface and filament together dictate what adhesion aid (if any) you should use.

"Glue stick" means a Pritt-style PVA glue stick. Magigoo and 3DLac work too. A thin even layer beats a thick blotchy one every time.

9. Replace the sheet or the nozzle

If you've worked through everything above and still can't get adhesion, the hardware itself is suspect.

• Worn PEI sheets develop bald spots where adhesion is gone forever. Flip the sheet (most are double-sided) or replace it. Expect ~1–2 years of daily use per side.
• A worn nozzle extrudes inconsistently. Brass nozzles wear in 200–500 hours of PLA, much faster with abrasive filaments. Hardened steel nozzles last 5–10× longer.
• A clogged nozzle under-extrudes specifically on the first layer when flow is at its highest. See Clogged nozzle and hotend.

Quick diagnosis table

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