TPU is tricky — but once you nail the settings, it's incredibly useful. Here's how to print flexible filament without jams, stringing, or failures.
Print speed: 15-25 mm/s (SLOW is key)
Retraction (direct drive): 0.5-1.0 mm / 15-25 mm/s
Retraction (Bowden): Avoid if possible — very difficult
Nozzle temp: 220-235°C (brand-dependent)
Cooling: 50-100% (unlike rigid materials)
Critical: TPU is extremely difficult on Bowden systems. The long PTFE tube allows the filament to compress and buckle. Direct drive is strongly recommended.
| Factor | Direct Drive | Bowden |
|---|---|---|
| TPU Suitability | Excellent | Very Difficult |
| Max Speed | 25-30 mm/s | 10-15 mm/s (slow!) |
| Retraction | 0.5-1.5 mm | 0-2 mm (often disabled) |
| Jamming Risk | Low | High |
TPU comes in different hardnesses measured in Shore A. Lower number = softer/more flexible.
| Hardness | Flexibility | Printability | Best For |
|---|---|---|---|
| 85A Shore | Very Flexible | Hard (expert only) | Extreme flex parts, gaskets, seals |
| 95A Shore ⭐ | Flexible | Medium (recommended) | Phone cases, grips, shock absorbers |
| 98A Shore | Semi-Flexible | Easy | Functional parts needing some flex |
| Setting | Direct Drive | Bowden (if attempting) |
|---|---|---|
| Print Speed | 15-25 mm/s | 10-15 mm/s |
| First Layer Speed | 10-15 mm/s | 8-10 mm/s |
| Retraction Distance | 0.5-1.5 mm | 0-2 mm (often disabled) |
| Retraction Speed | 15-25 mm/s | 10-20 mm/s |
| Nozzle Temp | 220-235°C | 225-240°C (slightly hotter) |
| Bed Temp | 30-50°C | 40-50°C |
| Cooling Fan | 50-100% (after first layer) | 50-100% |
❌ Filament jamming in extruder
✓ Slow down — 20mm/s max. Reduce retraction to 0.5mm. Check for Bowden tube gaps.
❌ Severe stringing
✓ Lower temp by 5°C. Increase cooling. Use "avoid crossing perimeters". Accept some stringing is normal.
❌ Under-extrusion / skipping
✓ Increase temp to 230-235°C. Slow down print speed. Reduce retraction.
❌ First layer not sticking
✓ Increase bed temp to 50°C. Slow first layer to 10mm/s. Add thin glue stick layer.
❌ Blobs and zits
✓ Lower temp. Reduce retraction speed. Dry filament (TPU absorbs moisture).
Dry your TPU before printing
TPU absorbs moisture fast. Dry at 50°C for 4h. Wet TPU = bubbles and stringing.
Disable "combing" / avoid perimeters
Combing causes long non-printing moves inside the part — TPU will string. Let it cross outside.
Use "linear advance" / pressure advance
Klipper PA or Marlin LA compensates for TPU compression. Drastically improves corners.
Print vase mode for flexible containers
No retractions, no seams, perfect for TPU water bottles or squeeze toys.