How to Fix Bed Adhesion Problems on the Kobra 3 PEI Sheet
kobra3bed adhesionpeifirst layer
PEI is excellent — but it needs care to work consistently. Here's the full troubleshooting and maintenance guide.
Troubleshooting by Symptom
| Symptom | Most Likely Cause | Fix |
|---|---|---|
| Nothing sticks at all | Dirty PEI (oils from handling) | IPA clean |
| Sticks then pops off during print | Z too high | Lower Z offset |
| Corners lifting only | Not hot enough / drafts | Raise bed temp, brim |
| Works sometimes, not others | Dirty or worn PEI | Deep clean or replace |
| PETG fused to PEI | No release agent | Use glue stick |
The IPA Clean (Do This Before Every Print)
- Wet a lint-free cloth or paper towel with 90%+ IPA
- Wipe the entire bed surface firmly
- Let dry completely (30 seconds)
- Don't touch the surface after cleaning
Never use: dish soap (leaves residue), window cleaner (ammonia damages PEI), acetone (destroys PEI surface)
Deep Clean (Weekly or When Adhesion Degrades)
- Remove PEI sheet if it's magnetic
- Wash with dish soap and warm water — just this once
- Rinse thoroughly
- Dry with a lint-free cloth
- Final wipe with IPA
Z Offset
Z offset is the most common cause of adhesion failures:
- Too high = filament doesn't press into bed = pops off
- The first layer should be visibly squished — lines just touching each other
- Adjust in 0.025 mm increments
When to Replace the PEI Sheet
- Deep scratches that prints catch on
- Spots that no longer adhere even after cleaning
- Bubbles or delamination
- After ~500 prints as a rough guide
Material-Specific Notes
| Material | Bed Temp | Notes |
|---|---|---|
| PLA | 60°C | IPA clean only |
| PETG | 80–85°C | Glue stick as release agent |
| ABS | 105–110°C | ABS slurry or Magigoo |
| TPU | 40–50°C | Clean PEI, low temp |