How to print TPU: settings for flexible filament
TPU 95A prints best at 215–230 °C on a 40–60 °C bed, slowly (about 20–40 mm/s), with short, gentle retraction and a direct-drive extruder. Start with 95A, dry the spool first, and let the part fan run at 30–100%. Get those right and you can print phone cases, gaskets, grips and bumpers that bounce instead of break.
- Buy 95A for your first TPU. Softer grades are much harder to feed.
- Nozzle 215–230 °C, bed 40–60 °C. Start at 220 °C and 50 °C.
- Slow down: about 20–40 mm/s, or use your slicer's TPU profile.
- Retraction 0.5–1.5 mm at 20–30 mm/s. Less is more.
- Dry it at 55–70 °C for 6–12 hours, and feed it from a short, smooth path (not a long Bowden tube or AMS).
TPU print settings table
Starting values for 95A TPU on a direct-drive printer. Brands differ: Polymaker rates PolyFlex TPU95 at 210–230 °C, Prusament TPU 95A at 220–240 °C. Your spool's label wins.
| Setting | Starting value | Notes |
|---|---|---|
| Nozzle temperature | 215–230 °C (95A) | Softer TPUs and faster printing usually need 5–10 °C more. |
| Bed temperature | 40–60 °C | Bambu uses 30–45 °C on its plates. Too hot and parts are hard to peel off. |
| Print speed | 20–40 mm/s | High-flow TPU grades on modern direct-drive printers go faster; use the vendor profile. |
| Volumetric flow | Keep it low | Generic TPU profiles typically cap flow at just a few mm³/s. |
| Acceleration | Lower than for rigid filaments | Sudden moves compress the filament and cause blobs. |
| Part cooling fan | 30–100% | 50% is a safe default. Less fan gives stronger layers; Prusa's generic flex advice is fan off. |
| Retraction distance | 0.5–1.5 mm (direct drive) | Polymaker lists up to 3–6 mm; start low and raise only if it oozes. Bowden: minimal or off. |
| Retraction speed | 20–30 mm/s | Fast retracts stretch soft filament instead of pulling it back. |
| Layer height | 0.16–0.28 mm | Thicker layers print faster and bond well. |
| Bed surface | Textured PEI; smooth PEI with glue stick | Glue stops soft TPU bonding too hard to smooth PEI. |
| Enclosure | No | Open the door or lid; a warm chamber softens TPU in the extruder. |
| Drying | 55–70 °C, 6–12 h | Prusa: 60 °C for 4–6 h. Polymaker and Bambu: 70 °C for 8 h. |
Like every filament, TPU needs more heat when you push it faster: the plastic spends less time in the melt zone. If you speed up and see gaps, raise the nozzle before you blame the extruder.
Shore hardness: pick the right TPU first
Shore hardness measures how firm a rubber is. On the A scale, higher numbers are firmer and easier to print. Hard TPUs are rated on the D scale, which is firmer still.
| Shore | Feel | Printer compatibility | Use for |
|---|---|---|---|
| 64D–68D (hard TPU) | Tough, bendy plastic | Easiest; stiff enough for filament changers. Bambu's "TPU for AMS" (68D) feeds through all AMS units | Bumpers, tough clips, multicolor flexible parts |
| 95A | Like a typical flexible phone case | Any direct drive; Bowden if slow and careful | Phone cases, watch straps, grips, gaskets |
| 90A | A bit softer | Most direct-drive extruders | RC tires, seals, shock mounts |
| 85A | Noticeably squishy | Good direct drive only. Bambu's A1 series doesn't support it | Soft gaskets, vibration dampers |
| 80A and below | Very soft and stretchy | Specialist extruders. Bambu Lab printers don't support TPU below 85A | Soft grips, stretchy bands |
First TPU? Use 95A. Nailed it? Try 90A or 85A. Don't start at 80A unless you enjoy untangling extruder gears.
Tip: Infill changes the feel as much as the filament. A 95A part with 2 walls and 10–15% gyroid infill feels far squishier than the same part printed solid.
Printer requirements for TPU
- Direct-drive extruder for anything softer than 95A. In a long Bowden tube, soft filament compresses like a spring and extrusion lags.
- A constrained filament path from the gears to the nozzle, with no gap where TPU can buckle out sideways.
- Gentle idler tension. Prusa recommends loosening the idler so the gears push TPU lightly; too tight and they chew or tangle it.
- A short, smooth feed from the spool. Standard TPU doesn't belong in most multi-material units: on Bambu printers only the AMS HT holds it, and only as a dry box feeding a dedicated outlet.
- A clean nozzle. Prusa suggests a cold pull before loading flexibles, since any partial clog shows up immediately.
Bambu Lab printers and Prusa's Nextruder machines (MK4, MK4S, CORE One, XL) handle 95A TPU with little or no tweaking, and so do most modern direct-drive toolheads. A stock Ender 3 with a Bowden tube can print 95A at about 20 mm/s with retraction nearly off; a direct-drive upgrade makes it far easier.
Your TPU keeps balling up around the extruder gears. What should you try first?
Soft filament buckles when it's pushed faster than it melts or pinched too hard. Slowing down and easing the idler tension fixes most tangles. Long retractions make it worse by yanking the filament back and forth.
How to fix TPU stringing
TPU strings stretch rather than snap, so they cling across the part. Fix them in this order:
- Dry the filament. Wet TPU is the number one cause of stringing, far ahead of retraction settings.
- Lower the nozzle 5 °C at a time until extrusion gets weak, then go back up 5.
- Keep travel inside the part (combing or "avoid crossing walls") so strings land where nobody sees them.
- Use short, slow retraction (0.5–1.5 mm at 20–30 mm/s). Long retracts don't help soft filament.
- Clean up with a heat gun: a quick pass shrinks fine hairs away.
More causes and fixes are in stringing and oozing, and the filament drying guide covers dryers and storage.
TPU troubleshooting: common problems and fixes
| Problem | Likely cause | Fix |
|---|---|---|
| Filament tangles around the gears | Too fast, idler too tight, gap in the path | Slow down, loosen the idler, constrain the path. |
| Gaps and thin walls | Flow too high for TPU | Lower speed or max volumetric flow; raise the nozzle 5 °C. |
| Heavy stringing | Wet filament or too hot | Dry at 55–70 °C, lower the nozzle, combing on. |
| Part welded to smooth PEI | TPU bonds strongly to PEI | Glue stick as a release layer, or use textured PEI. |
| First layer won't stick | Dirty plate or nozzle too high | Wash the plate, lower the Z-offset a little. |
| Blobs after travel moves | Pressure build-up in soft filament | Lower acceleration, slow travel, add a small wipe. |
| Clogs or jams after a few layers | Over-retraction or heat creep | Shorter retraction, open the enclosure. See clogged nozzle. |
| Won't feed from the AMS or MMU | Too soft for long feed paths | Feed from an external spool, or use a stiff grade such as 68D. |
| Part too stiff or too soft | Wrong hardness or infill | Change walls and infill first, then the Shore rating. |
What TPU is good for (and what it isn't)
Phone cases, watch straps, gaskets and seals, tool grips, RC tires, bumpers, vibration-damping feet, and flexible hinges paired with a rigid PETG body.
Fine miniatures, sharp overhangs and bridges, parts with lots of support (TPU fuses to its own supports), and anything that must stay perfectly rigid.
TPU is extremely abrasion-resistant, stays flexible in the cold, shrugs off oils, and its layers bond strongly. Expect to pay more than for PLA, and expect large parts to take a while at TPU speeds.
Frequently asked questions
What are the best settings for TPU?
For TPU 95A, start at 220 °C (range 215–230 °C) on a 40–60 °C bed, print at about 20–40 mm/s, retract 0.5–1.5 mm slowly, and run the part fan at 30–100%. Dry the spool first.
Can you print TPU with a Bowden extruder?
Yes, with 95A TPU, if you print slowly (around 20 mm/s), keep retraction minimal and the filament path tight. Softer TPUs below about 90A really need a direct-drive extruder.
Can TPU go through an AMS or other filament changer?
Standard soft TPU usually can't; it buckles in long feed paths. Bambu Lab's AMS units don't support soft TPU (the AMS HT only stores it), but stiff grades made for it, such as Bambu TPU for AMS (68D), feed normally.
Does TPU need to be dried?
Yes, more than most filaments. TPU absorbs water quickly, and wet TPU strings and bubbles badly. Dry it at 55–70 °C for 6–12 hours and print from a dry box.
What does 95A mean on TPU filament?
It's the Shore A hardness. Higher numbers are firmer and easier to print; 95A feels like a typical flexible phone case. Lower numbers such as 85A are softer, stretchier and harder to feed.
Related articles
Sources & further reading
- Prusa Knowledge Base: Flexible materials and Prusament TPU 95A guide
- Bambu Lab Wiki: TPU printing guide
- Polymaker Wiki: PolyFlex TPU95 technical data sheet
- Bambu Lab Wiki: Filament drying recommendations
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