TPU (Thermoplastic Polyurethane) is an incredible material. It is basically rubber. You can print custom gaskets, flexible grommets, intake seals, and shock-absorbing mounts.
However, printing a material that behaves like a wet noodle can be challenging. Here is how to conquer TPU.
1. Dry Your Filament!
TPU is incredibly hygroscopic (it absorbs moisture from the air). If you print wet TPU, it will boil in the nozzle, pop, string everywhere, and look like a sponge.
- Fix: Dry the filament in a filament dryer or food dehydrator at 55°C for 6-8 hours before printing.
2. Slow Down
Because it's soft, pushing TPU too fast causes it to buckle and jam inside the extruder gears.
- Speed: Keep your print speeds under 30-40 mm/s. (Though some modern High-Speed TPUs and Bambu printers can go faster).
3. Retraction Settings
Retraction pulls the filament back to prevent stringing when moving between parts. Pulling a rubber band doesn't work well.
- Direct Drive Extruders: Keep retractions very short (1-2mm) and slow.
- Bowden Extruders: TPU is notoriously difficult on Bowden setups. Turn retraction completely OFF if you keep getting jams, and just accept a little bit of stringing that you can snip off later.
4. Don't Squish the First Layer Too Much
TPU adheres insanely well to PEI and Glass beds. If you squish it too hard, it will permanently fuse to your build plate and tear it when you try to remove it. A light application of glue stick acts as a safe release agent.