Printing with Flexible Filaments (TPU/TPE)

The Wobbly World of Flexible Filaments

Flexible filaments — primarily TPU (Thermoplastic Polyurethane) and the broader class of TPE (Thermoplastic Elastomer) materials — open up print applications that rigid filaments simply cannot achieve. Phone cases with genuine drop protection. Custom gaskets and seals. Shock-absorbing drone motor mounts. Ergonomic grips and tool handles. Flexible hinges and living joints. Tyre-tread models for RC vehicles. These applications need a material that bends, compresses, and recovers — and TPU delivers exactly that.

The reputation of flexible filaments for being difficult is justified but often overstated. The difficulty is real: flexible materials resist the forces that drive them through an extruder, buckling and jamming in ways rigid filaments never do. But with the right setup, settings, and technique, TPU is entirely manageable. Thousands of Australian makers print it routinely without drama.

Shore Hardness: Choosing the Right Flexibility

TPU is rated by Shore A hardness — a measure of resistance to indentation. Lower numbers are softer and more rubber-like: 85A TPU is very soft and flexible, similar to a soft rubber band. 95A is firmer — think of a car tyre or boot sole. 98A is at the stiffer end of the flexible range, sometimes called "semi-flexible." For most makers' first TPU project, 95A is the sweet spot: flexible enough for grip surfaces and impact absorption, firm enough to print reliably without demanding a perfect direct-drive setup. 85A is genuinely difficult — only attempt it on a well-configured direct drive setup.

Hardware Requirements: Direct Drive First

A direct drive extruder is strongly recommended for TPU printing. The short, direct path from extruder gears to hotend gives you precise control over the elastic filament — it can't buckle in a long Bowden tube because there's almost no tube to buckle in. With a well-configured direct drive setup, 95A TPU prints reliably. On a Bowden printer, 95A is possible but requires extremely careful settings and a perfect Bowden setup with zero slop at the fittings. 85A on Bowden is not recommended for beginners.

The Golden Rules for TPU Success

Print Slow: This is the most important rule. 20–30mm/s for all moves, including travel. Higher speeds cause the elastic filament to compress and spring back in the Bowden tube or extruder path. Minimise Retraction: Retracting an elastic filament causes it to spring back further than commanded and potentially jam. Use 0–1mm retraction on direct drive; eliminate retraction entirely if you're getting jams, and rely on combing mode and temperature management to control stringing instead. Print Hot: 220–240°C encourages smooth, consistent flow. Dry the Filament: TPU is highly hygroscopic — wet TPU produces a rough, bubbly surface and terrible layer adhesion. Dry at 55–60°C for 4–6 hours before printing, and use a filament dryer for active drying during long prints in humid conditions (see our filament storage guide).

Starting Your First TPU Print

Choose a simple, small model for your first TPU print — a flat disc, a small phone grip, or a simple gasket. Don't attempt a complex, multi-hour TPU print until you've successfully printed several simple pieces. Check that the path from the extruder to the hotend is completely smooth and that there's no point where the flexible filament can catch or buckle. Load the filament slowly and manually verify it feeds smoothly before starting the print. Start with 95A Shore hardness and work down if you need more flexibility later.