TPU Printing Guide for Bambu Lab Printers

TPU prints gaskets, phone cases, wheels and bumpers no rigid filament can replace — but it is a soft, stretchy material being pushed through a machine designed for stiff plastic. Follow a handful of hard rules and TPU is surprisingly reliable; break them and it jams in minutes.

The five hard rules

1. Keep standard TPU out of the AMS. Soft filament buckles in the AMS feed path — not even 95A shore hardness is safe. The only exception is Bambu’s dedicated “TPU for AMS”, a firmer 68D material designed for it. Everything else prints from the external spool holder.
2. Zero drag on the spool. A soft filament column cannot pull against resistance; any friction in the path shows up as under-extrusion. Make sure the spool spins freely.
3. Dry it: 8 hours at 70 °C — and 70 is the maximum. Wet TPU bubbles, strings and extrudes unevenly. Dry first, tune afterwards.
4. Never increase retraction to fight stringing. Long or fast retractions stretch the filament like a rubber band and buckle it inside the extruder.
5. Keep flow modest. TPU cannot be pushed through the nozzle fast. When in trouble, cap the volumetric speed low and let the printer slow itself down.

Baseline: Bambu’s stock TPU profile

Values from the Bambu TPU 95A HF profile (X2D generation):

Note the bed temperature: TPU’s softening point is around 30 °C, which is why the plate runs at only 35 °C — a hot bed would keep the base rubbery and wobbly.

Adhesion: the opposite problem

TPU doesn’t struggle to stick — it sticks too well. On smooth PEI it can weld itself down hard enough to damage the coating when you pry the part off, so apply a thin layer of glue stick as a release agent. Textured PEI at 35 °C is the best everyday plate. The SuperTack is marked incompatible in Bambu’s profile for the same reason: bonding so strong that removal tears the surface.

Fixing the two classic TPU problems

Stringing

Some stringing is the price of TPU — but wet filament multiplies it. The fix order: dry the spool (8 h at 70 °C), then lower the nozzle about 10 °C toward 220–230 °C. Do not raise retraction past the stock 0.8 mm, and don’t speed it up past 10 mm/s — fast retraction grinds soft TPU.

Under-extrusion and jams

Gaps, thin lines or a grinding extruder mean the flow is too high for the soft filament. Lower the max volumetric speed to 3–8 mm³/s (Filament settings → Filament) and re-check that the spool feeds without resistance. If the extruder already jammed, clear it before tuning — see the clogging guide.

Brand cheat sheet

Shore hardness matters more than brand: a 95A filament (all of the above) is the easiest flexible to print; anything softer needs slower speeds and even gentler handling. Note how far the manufacturer nozzle ranges spread — SUNLU starts at 190 °C while eSUN runs up to 250 °C — so when a non-Bambu TPU misbehaves at the stock 230 °C, check its own spool label before assuming the settings are broken.

Design for TPU

Half of TPU success is asking it to print sensible shapes. Flat, wide parts (gaskets, pads, mats) print almost effortlessly; tall thin towers wobble because the printed part itself flexes as the head moves. Where you can, print flexible parts lying flat, keep walls at two or more perimeters so the part has structure, and expect small details to come out slightly softer-edged than PLA would give you — that’s the material, not your tuning.