How to Print TPU: Slow Down and Tune Retraction
Direct drive vs Bowden
Direct-drive extruders push the filament right at the hotend, with no long PTFE tube for the soft TPU to buckle into. This is the single biggest factor in TPU print success. Bowden printers can handle TPU 95A and firmer with care, but 85A and 90A almost always fail in Bowden due to buckling.
Speed: slow is the answer
- TPU 85A: 15 to 20 mm/s
- TPU 90A: 20 to 30 mm/s
- TPU 95A: 25 to 40 mm/s
- TPU 95A HF: 40 to 60 mm/s
- TPU 98A: 30 to 50 mm/s
- TPU D-scale: 30 to 60 mm/s (more like PETG)
Retraction: less is more
TPU stretches when retracted, then springs back inconsistently. Heavy retraction causes more stringing, not less. Start at 0.5 to 2 mm at slow speed (20 to 30 mm/s). Some setups print TPU best with zero retraction.
Print settings
- Nozzle 220 to 240 C (top end for HF variants)
- Bed 40 to 60 C with glue stick or PEI
- Layer fan 50 to 100 percent for soft TPU; less for harder grades
- Walls 3 to 5 for functional flex parts
- Infill 10 to 30 percent gyroid for soft feel; higher for firmness
Drying TPU
TPU is hygroscopic. A spool left out for a week absorbs enough moisture to print with popping and stringing. Dry at 50 C for 6 to 8 hours before printing, especially in humid climates.
Bed adhesion
TPU sticks well to most surfaces. Watch the opposite problem: it can stick so well that removing the print damages the build plate. Glue stick on PEI gives a controlled release.
Browse the range
All TPU sorted by Shore hardness from 85A to 75D.