Printing with TPU: what to know before you buy
Flexible filament is genuinely different to print. Shore hardness explained, why direct drive matters so much, and the settings that separate success from a nest of spaghetti.
TPU makes phone cases, gaskets, drive belts, grippy feet and anything else that needs to squash. It is also the filament most likely to defeat a printer that handles everything else fine — not because it is exotic, but because pushing a soft material through a narrow tube behaves like pushing rope.
Shore hardness matters more than brand
TPU is sold by hardness on the Shore A scale, and this is the number to look at:
- 95A — the common general-purpose grade. Firm, like a shoe sole. The easiest to print and the right first choice.
- 85–90A — noticeably softer and squashier. Harder to feed.
- Below 85A — very soft, and genuinely difficult on most consumer machines.
If a listing does not state a Shore rating, that is a small warning sign in itself. Compare what is currently available at TPU ranked by £/kg.
Direct drive versus Bowden
This is the single biggest factor. A direct-drive extruder grips the filament right above the nozzle, so there is almost no distance in which soft filament can buckle. A Bowden setup pushes it down a long tube, where it compresses like a spring, and the result is inconsistent extrusion and blobs.
Bowden printers can print 95A TPU with patience — slow speeds, minimal retraction, a well-constrained filament path. Softer grades on Bowden are a project rather than a print.
The settings that actually matter
- Slow down. 15–25 mm/s. This is the one that fixes most problems. TPU does not respond well to being rushed.
- Retraction: minimal. Long retractions on a stretchy material pull the filament apart rather than pulling it back. Start near zero and add only if stringing demands it.
- Temperature: 220–235 °C as a starting point.
- Keep it dry. TPU absorbs moisture quickly and prints badly when wet — see filament storage.
- No sharp turns in the path. Make sure the spool unwinds freely; TPU binding on the reel will stall the extruder.
Design differences
Flexibility comes from geometry as much as material. The same part printed at 15% infill and at 60% infill will feel entirely different. Thin walls flex, thick walls do not. If a TPU part feels too stiff, reduce infill and wall count before buying softer filament.
Realistic expectations
Surface finish is generally rougher than PLA, overhangs are worse, and small details are softer. Supports are miserable to remove because the part flexes away from your tools. Design to avoid needing them.
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Last reviewed 10 September 2026.