Printing PETG on the Kobra 3 — Settings and Bed Prep
kobra3petgsettingsbed adhesion
PETG sits between PLA and ABS — tougher than PLA, easier than ABS, but it has its own quirks. Here's how to get it dialed on the Kobra 3.
Why PETG Is Tricky
PETG loves to stick — too much. It can bond permanently to PEI if you're not careful, and it strings aggressively if temps are wrong.
Recommended Settings
| Setting | Value |
|---|---|
| Nozzle temp | 235–245°C |
| Bed temp | 80–85°C |
| First layer bed | 90°C |
| Print speed | 80–100 mm/s |
| First layer speed | 25 mm/s |
| Cooling fan | 30–50% |
| Retraction | 1.2–1.5 mm @ 30 mm/s |
| Layer height | 0.2–0.25 mm |
Bed Prep — Critical
PETG and PEI will bond if you're not careful:
- Clean PEI with IPA before every print
- Apply a thin layer of glue stick as a release agent — this is the single biggest tip
- Alternatively lower bed to 75°C if parts keep sticking at 85°C
- Let parts cool completely before removing — PETG releases easier cold
Dealing With Stringing
PETG strings more than PLA. Tune in this order:
- Raise retraction to 1.5 mm (direct drive limit)
- Increase travel speed to 200 mm/s
- Drop temp by 5°C
- Enable wipe on retract
- Print a retraction tower to find sweet spot
Common Issues
| Problem | Fix |
|---|---|
| Part fused to PEI | Use glue stick next time, pry carefully cold |
| Heavy stringing | Lower temp, increase retraction/travel |
| Layer separation | Raise temp 5°C, reduce fan |
| Wet prints (bubbling) | Dry at 65°C for 6 hours |
Good Uses for PETG
Mechanical brackets, food-safe containers, outdoor parts, flexible clips. Not as heat-resistant as ABS/ASA but far easier to print.