TPU insole printing.
A starting profile you can tune.
Printing insoles in flexible TPU is easy to get wrong: stringy, under-extruded, or peeling off the bed. This guide is how to dial in TPU insole printing, with a starting slicer profile, the prep that avoids common failures, fixes for the ones that still happen, and how to finish with a top cover. Bring your own STL, or generate one in minutes.
A starting TPU profile for insoles.
An example starting profile for printing insoles in flexible TPU on a direct-drive FDM printer. Treat it as a baseline and tune from here to your filament and machine, since TPU brands vary in the temperature and flow they like best.
| Setting | Value | Why |
|---|---|---|
| Material | TPU 95A | The grade this example profile is written for. Firmer TPU is usually easier to print; softer 85A–90A needs slower, gentler settings. |
| Nozzle temp | 220–235 °C | Enough flow for clean flexible extrusion; drop it if you see stringing. |
| Bed temp | 30–45 °C | Light heat helps the first layer stick without over-softening. |
| Nozzle | 0.4 mm | Standard; no special hardware needed for plain TPU. |
| Speed | ~30 mm/s | Slow and steady keeps the soft filament feeding cleanly. |
| Infill | 20% gyroid | Flexes and rebounds evenly in all directions — the cushioning structure. |
| Walls | 3 perimeters | Shell strength and a clean surface over the infill. |
| Layer height | 0.2 mm | A balance of print time and a smooth top surface. |
| Flow | ~103–105% | A touch of over-extrusion fills flexible gaps for a solid feel. |
| Retraction | Low / minimal | TPU oozes; keep retraction short (or off on direct drive) to avoid jams. |
Direct-drive extruder strongly recommended. Flexible TPU feeds unreliably through long Bowden tubes. A Bambu Lab, Prusa MK-series, or Voron-style direct-drive setup handles it far better; on Bowden, slow down and tune retraction carefully.
Check your filament's data sheet first. Recommended temperatures differ by brand and build plate — for example, Bambu Lab TPU 95A HF: nozzle 220–240 °C, bed 30–35 °C; Polymaker PolyFlex TPU95: 210–230 °C, 25–60 °C; Prusa’s general flexible-materials guide: 230–245 °C, 60–75 °C. The values above are an untested example within that spread, not a guarantee for your printer.
Four things to set up first.
Many TPU print problems start before the first layer. A few minutes of prep can save a scrapped multi-hour print, so get these four right before relying on the settings above.
TPU absorbs moisture
A damp spool spits, strings, and pops during printing. Dry TPU before you print, following your filament's data sheet (Bambu Lab and Polymaker both list 70 °C for 8 hours), in a filament dryer or forced-air drying oven — not a microwave or kitchen oven — and keep it dry while it runs.
Feed the soft filament cleanly
A direct-drive extruder pushes flexible TPU far more reliably than a long Bowden tube. On Bowden, slow right down and tune retraction, or expect jams on longer prints.
Clean plate, light heat
Wipe the plate so it's grease-free, set the bed to 30 to 45 °C, and add a brim. TPU sticks well to a clean PEI or textured plate, sometimes almost too well.
Lay it on its base
Print the insole flat, base down. A standard insole shape has no steep overhangs, so it needs no supports. That keeps the underside clean and cuts print time and filament.
Fixing the four common TPU insole print fails.
These are four common TPU insole print failures. Here's the symptom, the likely cause, and the fix for each, so you can diagnose a bad print at a glance instead of guessing and reprinting.
Wispy strands across the print
Nozzle too hot, retraction too low, or wet filament. Fix: drop nozzle temp in 5 °C steps, add modest retraction, and dry the TPU (filament dryer or forced-air drying oven) before printing.
Gaps, thin walls, weak feel
The soft filament is slipping or the flow is too low. Fix: slow to ~30 mm/s, nudge temp up 5 °C, raise flow toward 105%, and check the extruder tension — direct drive helps most here.
Corners peel off the bed
Poor first-layer adhesion. Fix: clean the bed, add a little bed heat (30–45 °C), slow the first layer, and use a brim. TPU normally sticks well once the plate is clean.
Splits between layers under flex
Layers aren't bonding — too cool or too fast. Fix: raise nozzle temp, slow down, bump flow slightly, and turn part-cooling fans down so layers fuse.
Add a top cover for feel.
A printed TPU insole works bare, but a thin top cover changes the feel underfoot and protects the printed surface from wear. Common choices are EVA foam (soft and cheap), fabric or microfiber (breathable and grippy), and leather or suede (a premium feel). A 1.5 to 3 mm cover is typical: thicker adds cushioning but eats into shoe volume, so match it to the shoe you'll actually wear the insole in.
Gluing it on, cleanly
Use a contact adhesive, apply a thin even coat to both surfaces, and let it tack until touch-dry, then press from the heel forward to push out bubbles. Trim the cover flush once the glue has cured, not before. For durometer choices by activity and a full top-cover walkthrough, see the TPU hardness & top-cover guide.
Don't have an insole STL yet?
These settings will print any insole STL, but the fit is what makes it worth wearing. A generic marketplace STL isn't shaped to your foot; a fitted one is. Generate a custom insole in Ergono3D from a guided foot profile (no CAD, no scanner), preview it in 3D, and export a print-ready STL to run with the settings above. Left and right come as a matched pair, and you can re-export after a wear test. If you already have a file that needs a dimensional correction, resize, widen, or trim the insole STL before slicing.
TPU insole printing questions, answered.
/ 01What TPU hardness should I use for insoles?
There is no single default hardness. 85A is the softest and usually the hardest to print, 95A is the firmest and usually the easiest, and 90A sits in between. Choose by the feel you want and what your printer handles well; the settings on this page are an example profile for 95A. See the TPU hardness & top-cover guide for choosing by activity.
/ 02Do I need a direct-drive extruder to print TPU insoles?
A direct-drive extruder is strongly recommended for flexible TPU — it feeds the soft filament reliably. Bowden setups can print TPU but need slower speeds and careful retraction tuning to avoid jams.
/ 03Why is my TPU insole stringing?
Stringing usually means the nozzle is too hot, retraction is too low, or the filament has absorbed moisture. Drop the nozzle temperature in 5 °C steps, enable modest retraction, and dry the TPU before printing.
/ 04What infill should I use for a TPU insole?
About 20% gyroid infill is a common starting point. Gyroid flexes fairly evenly in every direction; how well a printed insole cushions and how long it lasts depend on the TPU, walls, density, and use, so check it on your own test print.
/ 05How long does a pair of TPU insoles take to print?
Roughly 5–7 hours for a pair, depending on insole size, layer height, and print speed (around 30 mm/s for clean flexible extrusion).
/ 06Can I print insoles on a Bambu Lab or Prusa printer?
Yes. Bambu Lab, Prusa, and most modern FDM printers that handle flexible filament can print TPU insoles. Load a print-ready insole STL, apply the TPU settings above, and print.
/ 07Do TPU insoles need supports?
No, not for a standard insole shape. Printed flat on its base, an insole has no steep overhangs that need support. Skipping supports saves time and filament and keeps the underside clean.
/ 08Which TPU brand should I use?
Choose a TPU whose data sheet lists printing and drying settings, and start from those. Recommended temperatures differ between brands — for example, Bambu Lab lists a 220–240 °C nozzle for TPU 95A HF and Polymaker lists 210–230 °C for PolyFlex TPU95. Consistent filament diameter also helps flexible TPU feed reliably.
/ 09How do I dry TPU before printing?
Follow your filament's data sheet: Bambu Lab (TPU 95A HF) and Polymaker (PolyFlex TPU95) both list 70 °C for 8 hours. Use a filament dryer or a forced-air drying oven; Bambu Lab notes that microwave and kitchen ovens are not suitable. Drying is one of the first things to try for stringing and surface popping.
From your STL to a first test print.
Generate a custom insole STL, start from these TPU settings, and tune them on a test print — no CAD, no scanner, no lab.
Custom insole STL generator
Generate a print-ready insole STL from a guided profile — no CAD.
TPU hardness & top covers
Pick durometer by activity and finish the print for the right feel.
Orthotic design software
Use guided intake and editable parameters before exporting STL files for TPU production.