The first layer isn't sticking to the bed
80% of failed prints die on the first layer. The good news is it can be diagnosed just by looking at it: a proper first layer is a smooth surface, with no gaps between lines and no raised plastic.
What the failure looks like
Filament extrudes, but sticks to the nozzle and drags, or forms loose threads that come unbonded on their own. Sometimes it starts well in one area and fails in another.
Causes, most likely first
- 01
Nozzle too high
The number one cause. If the nozzle doesn't squash the filament slightly against the bed, the line stays rounded and comes loose.
- 02
Unlevel bed
Works well in the centre and fails at the corners (or vice versa).
- 03
Bed temperature too low
Each material has its window; below it, there's no adhesion.
- 04
Dirty or worn surface
PEI loses grip with grease and general wear.
- 05
First layer too fast
Above 30 mm/s, the plastic doesn't have time to settle.
Step-by-step fix
1. Don't level the bed cold; do it hot
Heat the bed and nozzle to operating temperature before levelling: the metal expands and changes the gap.
2. Adjust the Z-offset while printing
Print a single-layer test square and lower the Z in steps of 0.02 mm while printing until the lines touch each other without forming ridges.
3. Increase the bed temperature by 5 °C
It's cheaper to try this than to replace the build surface.
4. Reduce the first layer speed to 20-25 mm/s
And set the first layer height to 0.2-0.3 mm (never less than 75% of the nozzle diameter).
5. Clean with isopropyl alcohol
Never use acetone on smooth PEI: it damages it. Avoid detergents that leave a residue.
6. Increase the first layer flow to 105-110%
A quick trick for textured or slightly worn beds.
So it doesn't happen again
- Check the bed level every 20-30 printing hours or after moving the machine.
- Keep two magnetic sheets and rotate their use; they wear out.
- Always handle the sheet by the edges.
Related questions
Is glass or PEI better?
Textured PEI is the most convenient option for everyday PLA and PETG. Glass gives a perfect mirror finish on the bottom, but requires hairspray or glue for PETG.
Does an automatic bed levelling sensor fix everything?
No. ABL compensates for the bed shape, but you still set the Z-offset yourself. An ABL with an incorrect offset will fail just the same.
Keep reading
What if it isn't worth your time?
Sometimes the part is more urgent than the learning curve. We're a workshop in Viladecavalls: send us the file and we'll print it with the right material and settings.
Still not working?
Tell Marco which printer and material you use and he'll tell you what to change.
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