How to print TPU and other flexible filament

What Shore hardness means, why direct drive helps, and the speed, temperature and retraction settings that get TPU through the extruder.

This article has partner links to 3DJake. If you buy through them, Printaro Tools may earn a commission. It doesn't change what we recommend.

Updated 2026-10-16

Short answer

Print TPU slowly, at about 20–30 mm/s, on a printer whose extruder sits right above the nozzle (direct drive). Use the nozzle temperature printed on the spool, and start with little or no retraction. Dry the filament first: TPU takes up water from the air easily.

A firm 95A TPU is the easiest flexible filament to start with. Softer grades bend more, but they are harder to push through the extruder.

Shore hardness in plain words

Flexible filaments are sold by hardness on the Shore A scale. A higher number means a harder material. Smooth-On, a maker of mold rubbers, describes a 70A rubber as about as hard as a car tire. The A scale overlaps with the Shore D scale used for harder plastics: Smooth-On gives 95A as roughly the same as 45D. Very soft rubbers and gels are measured on yet another scale, Shore 00.

Many TPU filaments are sold as 95A, for example Polymaker PolyFlex TPU95 and Bambu Lab TPU 95A HF. Softer grades exist too: Bambu Lab also lists TPU 85A and 90A. Prusa's guide to flexible materials puts TPU at roughly 60A to 90A and notes that the softer the filament, the harder it is to print.

At 95A, the shape of the part decides most of how it feels. A thin wall bends easily. A solid block hardly gives at all. TPU also stretches a long way before it tears: Polymaker's data sheet gives an elongation at break of about 550 % for PolyFlex TPU95, so a strip can stretch to several times its own length.

When you buy, look for the Shore value on the label and pick 95A for a first try. 3DJake has a range of flexible filamentPartner link that includes TPU.

Direct drive vs Bowden

There are two common ways to feed filament. A direct drive extruder has its gears on the print head, a few centimeters above the nozzle. A Bowden extruder sits on the frame and pushes the filament through a long plastic tube to the nozzle.

Stiff filament like PLA behaves like a rod in that tube. Flexible filament behaves more like a rope: push it and it bends, bunches up or wraps around the gears instead of moving forward. Simplify3D's material guide states that most fully flexible filaments need a direct drive extruder for best results, while some partly flexible ones work with Bowden. The shorter and tighter the path from the gears to the hot end, the better.

If your printer has a Bowden tube, you can still try. Choose a firm grade such as 95A, print slowly, keep retraction short and check whether your printer's maker supports flexible filament on that model. Prusa's guide also suggests loosening the extruder idler so the gears push the filament only gently and don't chew into it.

Help the filament leave the spool too. Simplify3D suggests mounting the spool above the printer so it unwinds downward, on a holder that turns freely. Every bit of drag on the spool has to be pushed through by soft filament.

Speed, temperature and retraction

Speed is the setting that matters most. Prusa gives about 20 mm/s as a typical speed and 30–40 mm/s as the maximum. Polymaker gives 30–50 mm/s for PolyFlex TPU95, and Simplify3D suggests 20 mm/s as a starting point. Printing too fast makes the filament buckle in the extruder and can clog it. Keep the speed even as well: sudden changes in flow are hard to control with a soft filament.

Nozzle temperature ranges differ by maker. Prusa gives 230–245 °C for flexible materials, Polymaker 210–230 °C for PolyFlex TPU95, and Simplify3D 225–245 °C. Start from the range on your spool. The temperature tower has a TPU preset that prints blocks from 235 °C down to 205 °C in 5 °C steps. If your spool asks for more, raise the highest temperature in the tool before you download.

Bed temperature is low: Prusa gives 60–75 °C and Polymaker 25–60 °C. TPU can bond very hard to a smooth sheet. Prusa advises glue stick as a separating layer on smooth PEI and says a textured sheet needs none.

Part cooling is where the sources disagree. Prusa's guide says to keep the fan off. Polymaker's sheet lists it as on, and Simplify3D calls a cooling fan required. A reasonable path is to start with your slicer's own TPU profile, turn the fan down if layers come apart, and up if overhangs droop.

Retraction pulls filament back while the nozzle travels, and soft filament compresses instead of moving back. Prusa and Simplify3D both suggest starting with retraction off and then adding a small amount while you watch the result. Polymaker's sheet gives 3–6 mm at 40–60 mm/s for PolyFlex TPU95, which shows how much printers and filaments vary. TPU strings easily, so a retraction test is worth printing once you have a temperature that works.

Designing for flex

Several generators here say in their printing tips that TPU is the right or the better material. These are the ones whose tips name it:

Gasket generator: flat rings, flange gaskets and O-rings. The tips ask for TPU 95A or softer for anything that has to seal, printed slowly with 100 % infill, and warn not to use a printed gasket for gas, fuel, drinking water under pressure or hot parts.
Strain relief: a cable sleeve that snaps into a panel hole. The tips say TPU only, because the slotted tail has to bend. PLA or PETG will snap.
Timing belt: GT2 and HTD belts as a loop or a strip. The tips ask for TPU 95A or softer, and note that a printed belt has no cords inside, so it stretches and suits light drives only.
Door stop: a wedge with grip grooves. TPU grips best on smooth floors.
Tube end cap: plugs and caps for chair legs and frames. TPU plugs grip best and are quiet on floors.
Spring generator: it has a "Soft (TPU)" preset for a soft spring.

Shape decides stiffness

With TPU you set the stiffness of a part partly in the slicer. More walls and more infill make a part firmer. Less infill makes it softer and springier. That is why the gasket tips ask for 100 % infill: a seal needs solid material with no gaps for water to find.

A part that has to fit over something else can be made a little smaller than the object, because TPU stretches. Simplify3D suggests a negative tolerance for this, so the part stretches on and holds by itself. If a cap comes out too tight, print it again a little larger.

If a part needs supports, leave more room between support and part than you would for PLA. Prusa suggests a top contact Z distance of 0.3 mm.

For the basics of picking a material, see choosing a filament.

Common mistakes

Printing at PLA speed. The filament buckles in the extruder and the print stops extruding. Slow down first, before you change anything else.
Long retraction. Soft filament compresses, oozes and can jam. Start with retraction off or very short.
Wet filament. TPU takes up water easily, and wet TPU strings and bubbles. Dry it before you print. See how to dry filament.
A spool that is hard to turn. The extruder has to pull it, and soft filament stretches instead. Use a holder that turns freely.
Printing on bare smooth PEI. TPU can stick so hard that it damages the sheet. Use glue stick or a textured sheet.
Starting with a very soft grade. 85A and softer are harder to feed. Learn the settings on 95A first.
Using a raft. Simplify3D advises against it, because the raft layers push a lot of filament at once.

Frequently asked questions

Can I print TPU on a Bowden printer?

It can work with a firm grade such as 95A, a slow speed and short retraction. Simplify3D states that most fully flexible filaments need a direct drive extruder.

What does 95A mean?

It is the hardness on the Shore A scale. Higher is harder. 95A is a firm TPU that bends in thin walls but feels solid in a thick block.

Should retraction be off for TPU?

Start with it off or very short, then add a little at a time. Print a retraction test to see where the strings stop.

Do I need to dry TPU?

Usually, yes. TPU takes up water from the air easily. Prusa gives 60 °C for 4–6 hours and Polymaker 70 °C for 8 hours for its PolyFlex TPU95.

Which bed surface works for TPU?

A textured sheet, or smooth PEI with glue stick as a release layer. TPU can stick hard enough to bare smooth PEI to damage it.