Printing with TPU: what to know before you buy

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.

Questions people ask

Is TPU hard to print?

TPU is harder to print than PLA because it is soft and can buckle or compress on its way to the nozzle. The common 95A grade prints reliably on a direct-drive printer if you slow down to about 15 to 25 mm/s and keep retraction to a minimum. Softer grades below 85A are genuinely difficult on most consumer machines.

What does 95A mean on TPU filament?

95A is the Shore A hardness of the TPU, and it describes how firm the printed material feels. 95A is the common general-purpose grade, firm like a shoe sole, and the easiest to print. Grades of 85A to 90A are noticeably softer and harder to feed, and anything below 85A is very soft.

Can I print TPU on a Bowden printer?

You can print 95A TPU on a Bowden printer with patience, using slow speeds, minimal retraction and a well-constrained filament path. A direct-drive extruder is far better, because it grips the filament right above the nozzle and leaves no room for the soft filament to buckle. Softer grades on a Bowden setup are very difficult.

What speed and temperature should I print TPU at?

Print TPU slowly, at about 15 to 25 mm/s, with a nozzle temperature of 220 to 235 degrees Celsius as a starting point. Use little or no retraction, because long retractions stretch the filament instead of pulling it back. Slowing down is the single change that fixes most TPU problems.

Does TPU need to be dried before printing?

Yes, TPU usually needs to be kept dry or dried before printing. It absorbs moisture from the air quickly and prints badly when wet, with stringing, bubbling and a rough surface. Store it in a sealed box with desiccant, and dry any spool that has been left out.

How do I make a TPU print softer or more flexible?

Reduce the infill and the number of walls before buying softer filament. Flexibility comes from the geometry as much as the material: the same TPU part feels completely different at 15 percent infill than at 60 percent, and thin walls flex where thick walls do not.

What is TPU filament used for?

TPU filament is used for parts that need to bend, squash or grip: phone cases, gaskets, drive belts, grippy feet, tyres and protective bumpers. It gives a rougher surface and softer details than PLA, and supports are hard to remove, so designs that avoid supports work best.