How to Print TPU and Flexible Filaments on Any FDM Printer
Introduction
TPU (Thermoplastic Polyurethane) and other flexible filaments like TPE and TPC open a world of functional applications that rigid plastics cannot touch — phone cases, gaskets, drone bumpers, wearable straps, vibration dampers, and soft-touch grips. But flexible filament is notoriously difficult to print: it compresses, buckles, wraps around gears, and jams in Bowden tubes. The key to success is understanding how flexible filament behaves differently from PLA and adjusting your printer accordingly. This guide covers everything from extruder selection and retraction tuning to speed, temperature, and bed adhesion settings that produce clean, strong flexible prints on both Bowden and direct drive extruders.
What You Need
- TPU or TPE filament (95A shore hardness is easiest to start with)
- Direct drive extruder recommended (Bowden is possible with modifications)
- Bed surface that grips well (PEI, BuildTak, or glue stick on glass)
- Dry filament (flexible materials are very hygroscopic)
Understanding Flexible Filament Behavior
Flexible filament differs from rigid filament in critical ways:
- Compresses under pressure: Instead of pushing straight, it can bunch up in the extruder
- Bends easily: In a Bowden tube, it can form a U-shape and jam
- Stretches and retracts: Retraction pulls it back too far, then forward pressure compresses it again
- High friction: Sticky surface grips the Bowden tube walls
- Stringy: Oozes more than rigid filaments due to elasticity
Step 1: Extruder Selection
Direct Drive (Recommended)
Direct drive extruders position the motor directly above the hotend with minimal filament path (