Print slowly, as the filament maker recommends, use an extruder with a constrained filament path — direct drive is the usual choice — reduce or disable retraction, and keep the spool dry. Softer grades are harder to feed than the common 95A.
Flexible filament rewards slow, gentle settings and punishes speed.
Why TPU jams in extruders
TPU compresses and bends. Pushed quickly or through gaps in the filament path, it buckles inside the extruder instead of moving into the hotend.
Extruder setups that suit TPU
Direct drive extruders with a constrained path from gears to hotend. Correct tension: enough grip without crushing the filament. Printers and extruders that list flexible filament support say so.
TPU print settings
Slow speeds, following the filament maker’s recommended speed. Low retraction or none. Temperatures within the maker’s range. Little or no part cooling on the first layers for adhesion.
Shore hardness of TPU
TPU is sold by Shore hardness, such as 95A. Lower numbers are softer and harder to print. Starting with a harder grade makes learning easier.
Keeping TPU filament dry
TPU absorbs moisture, which causes stringing and bubbles. Drying before printing and printing from a dry box help on long prints.
Questions makers ask before buying
Can TPU be printed through a Bowden tube?
Harder grades sometimes can, slowly, with a tight-fitting tube. Softer grades usually need direct drive, because the filament compresses inside a long tube.
Why does TPU string so much?
It oozes easily and retraction is kept low to avoid jams. Drying the spool and printing at the lower end of the temperature range help.
Last reviewed 15 September 2026