Quick answer
TPU jams and clicks when the soft, elastic filament buckles before it reaches the nozzle instead of feeding through cleanly. The fix is to slow the print speed to roughly 15-30 mm/s, cut retraction to about 1-2 mm on a direct drive (or disable it entirely), print hot at around 220-235°C, and set the extruder idler to moderate tension so it grips the filament without crushing it. A direct drive extruder handles flexible filament far more reliably than a Bowden setup.
Why TPU is so hard to feed
TPU is soft and stretchy, so unlike rigid PLA it does not get pushed cleanly through the extruder. When there is too much resistance ahead of it, the filament compresses and coils up inside the extruder gears or the Bowden tube instead of advancing into the hotend. That buckling is what causes the clicking, skipping and under-extrusion people see with flexibles, so nearly every fix below is really about removing resistance and keeping the filament under control.
1. Slow your print speed down
Speed is the single biggest cause of TPU feeding failures. Drop your print speed to around 20-30 mm/s on a direct drive machine, and 15-20 mm/s if you are running a Bowden setup. If you still get clicking, keep lowering it. It also helps to cap the maximum volumetric speed in your slicer’s filament settings to something conservative like 3.6 mm³/s so fast infill or travel moves cannot outrun what the soft filament can handle.
2. Reduce or disable retraction
Long, fast retractions pull TPU back and let it bunch up in the extruder. Set retraction distance to about 1-2 mm on a direct drive extruder, or around 4-6 mm on Bowden, and use a slow retraction speed of roughly 20-25 mm/s. Turning retraction off entirely is a valid approach with TPU; you will get a little more stringing, but far fewer jams. Cleaning up stringing afterwards is much easier than clearing a buckled extruder.
3. Dial in the nozzle temperature
TPU that is too cold flows poorly and puts more back-pressure on the extruder, which encourages buckling. Print in the 220-235°C range on most direct drive machines (check your specific filament’s label, as some grades run 210-240°C). If you see under-extrusion or hear clicking, nudge the temperature up in 5°C steps to lower the resistance in the hotend.
4. Set moderate idler tension
The spring-loaded idler that presses the filament against the drive gear needs to be just right for TPU. Too tight and it crushes the soft filament into a flat, deformed shape that will not feed; too loose and the gear slips and grinds. Back the tension off to a moderate setting and watch the filament feed a purge line: it should advance smoothly with no flattening and no slipping.
5. Close gaps in the filament path
Any gap where TPU can escape sideways will cause a jam. On direct drive extruders, make sure the short PTFE liner seats fully against the drive gear so the filament cannot buckle in the gap. On Bowden setups, confirm the PTFE tube is pushed all the way in and secured at both the extruder and the hotend, with no gap at the couplers. A worn or loosely fitted tube is a very common hidden cause of flexible-filament jams.
6. Clear a partial nozzle clog
Because TPU is so soft, it is unusually sensitive to any restriction at the tip. A partial clog that a rigid filament would push through will stall TPU completely. If feeding is still poor after the steps above, do a cold pull (atomic pull) or heat the nozzle and push filament through by hand to clear residue, and make sure you are not mixing an abrasive or charred remnant from a previous material.
7. Dry the filament
TPU is hygroscopic and absorbs moisture quickly from the air. Wet TPU hisses and pops, extrudes inconsistently and worsens stringing, all of which can look like a feeding fault. Dry it in a filament dryer, food dehydrator or low oven at around 50°C for 4-6 hours before printing, and keep it in a sealed container with desiccant between prints.
8. Feed TPU correctly on a Bambu Lab AMS
On Bambu Lab machines, the standard AMS, AMS Lite and AMS 2 Pro are not designed for TPU, and forcing flexible filament through their internal path is a reliable way to jam the system. Feed TPU from an external spool holder straight into the extruder instead. Only the AMS HT officially supports TPU, and even then the filament must go through its dedicated rear TPU outlet rather than the normal automatic feed path.
Frequently asked questions
Why does my extruder click when printing TPU?
The clicking is the drive gear skipping because the soft filament has buckled and stopped advancing. Slow the print speed, reduce retraction and ease off the idler tension to fix it.
Can I print TPU with a Bowden extruder?
Yes, but it needs more tuning. Keep speeds down to 15-20 mm/s, minimise retraction, and make sure the PTFE tube is fully seated with no gaps. A direct drive extruder is strongly recommended for flexibles.
What temperature should I print TPU at?
Most TPU prints well between 220 and 235°C with a bed around 40-60°C, though some grades are rated 210-240°C. Always check the filament manufacturer’s recommended range first.
Should I use retraction with TPU?
Use as little as you can get away with: about 1-2 mm on direct drive, or disable it entirely. Excess retraction is one of the most common causes of TPU jams, and light stringing is easier to deal with than a buckled extruder.