TPU (Thermoplastic Polyurethane) is the material that makes 3D printing genuinely useful for a whole category of things other plastics can't touch - phone cases, gaskets, wheels, grips, wearables, and anything that needs to flex or absorb impact.
It's also one of the trickier filaments to print well. Here's everything you need to know.
TPU is a flexible, rubber-like plastic. It ranges from very soft and stretchy (Shore 85A - similar to a rubber band) to relatively firm and only slightly flexible (Shore 98A - similar to a hard rubber sole).
For beginners, 95A hardness is the sweet spot - flexible enough for most applications, firm enough to print reliably.
Popular TPU filaments:
| Setting | Recommended Value |
|---|---|
| Nozzle temperature | 220-235°C |
| Bed temperature | 30-60°C |
| Print speed | 20-30mm/s |
| Retraction | 0-2mm (direct drive) / Minimal (Bowden) |
| Cooling | Moderate (30-50%) |
| Infill | 20-40% for flexibility, 60%+ for rigidity |
Slow down. TPU does not respond well to speed. 25mm/s is a safe starting point - you can push to 40mm/s once you understand how your printer handles it, but anything faster risks bunching and jams.
This is the most important thing to know about printing TPU:
Direct drive printers (extruder motor on the toolhead) handle TPU well. The short, direct path from extruder to nozzle gives the flexible filament no room to buckle or bunch.
Bowden printers (motor on the frame, long PTFE tube to hotend) struggle badly with TPU. The flexible filament compresses and buckles in the long tube, causing massive under-extrusion, jams, and inconsistent flow.
If you have a Bowden printer like an older Ender 3 (non-SE/V3), TPU is possible but frustrating. Slow way down (15-20mm/s) and reduce retraction to near zero.
If you have a direct drive printer (Ender 3 V3 SE, Bambu Lab, Prusa MK4, etc.), TPU prints reasonably well with the settings above.
This trips up most beginners.
Too much retraction with flexible filament causes the extruder to grind against the soft material or cause the filament to buckle in the drive path.
Direct drive: Start with 0-2mm retraction at slow speed (20mm/s). Many TPU prints work better with retraction off entirely.
Bowden: Retraction should be 0-1mm maximum, or disabled. Counter-intuitive, but less retraction usually means fewer jams with TPU.
The most common TPU problem is the filament bunching up between the extruder gear and the hotend entry. This happens because:
Prevention:
TPU sticks well to most surfaces - sometimes too well.
If parts stick too aggressively to your PEI sheet, try a thin layer of hairspray or glue stick on top of it as a release agent.
TPU really shines for functional, everyday items:
Find TPU designs at Printables.com and Thingiverse.
TPU is highly hygroscopic - it absorbs moisture quickly and prints worse when wet. Signs of wet TPU: popping sounds, surface bubbles, weaker parts.
Store in an airtight container with silica gel desiccant. Dry at 45-50°C for 4-6 hours in a filament dryer if prints are coming out poorly.
TPU is rewarding once dialled in. The key rules:
Start with a simple test print - a small cube or a phone case - before attempting anything complex. Once you've got clean TPU prints, you'll wonder how you managed without it.