Printing with Flexible Filaments (TPU/TPE)

Jackson B.

The Wobbly World of Flexible Filaments

Flexible filaments, most commonly TPU (thermoplastic polyurethane), open up an entirely different category of FDM printing applications that rigid materials simply cannot achieve. From phone cases and vibration dampeners through to gaskets, ergonomic grips, flexible hinges, and drone components, TPU allows prints to bend, compress, and absorb impact while still maintaining excellent durability.

It is one of the most versatile speciality materials for consumer FDM printing, but it is also known to be difficult to work with.

That reputation is not entirely undeserved. Flexible filament behaves very differently from rigid materials like PLA or PETG. Instead of feeding cleanly through the extruder, TPU naturally wants to flex, compress, and buckle under pressure. This makes printer setup, extrusion control, and print speed far more important than they are with standard materials.

The excellent news is that with the right hardware and settings, TPU becomes far more manageable than many beginners expect.

Shore Hardness: Choosing the Right Flexibility

TPU is commonly rated using Shore A hardness, which measures how soft or firm the material feels.

Lower Shore ratings produce softer, more flexible filament. Higher numbers create firmer materials that still flex but behave more predictably during printing.

Very soft TPU around 85A feels similar to soft rubber and can bend effortlessly. At the other end, materials around 98A are often described as semi flexible and behave much closer to rigid plastics while still offering some elasticity.

For most users printing TPU for the first time, 95A is usually the ideal starting point. It offers enough flexibility for practical applications like grips and shock absorption while remaining firm enough to print relatively reliably on most direct drive setups.

Softer materials become progressively more demanding and generally require a well tuned printer to feed consistently without jamming or buckling.

Hardware Requirements: Direct Drive First

A direct drive extruder is strongly recommended for TPU printing.

Because the extruder sits very close to the hotend, the filament path remains short and tightly controlled. This minimises the opportunity for flexible filament to bend or compress before it reaches the nozzle.

Bowden setups can print firmer TPU successfully, but they require significantly more tuning and a very clean filament path with minimal movement or gaps around fittings. Softer TPU becomes especially difficult on Bowden systems due to the long tube allowing the filament to flex under pressure.

For most users, direct drive remains the simplest and most reliable path into flexible filament printing.

The Golden Rules for TPU Success

Print Slowly

• TPU prints best at slower speeds than rigid materials do.
• Around 20 to 30 mm/s is a good starting range for most printers.
• Higher speeds increase pressure inside the filament path and make buckling or inconsistent extrusion far more likely.

Minimise Retraction

• Retraction is one of the most significant causes of TPU jams.
• Pulling flexible filament backwards too aggressively can cause it to compress, twist, or catch inside the extruder path.
• Very low retraction values generally work best, and some printers perform better with retraction disabled almost entirely.
• Features such as combing mode and proper temperature tuning often help control stringing more effectively than aggressive retraction.

Print Hot

• TPU typically prints well between 220 and 240°C.
• Higher temperatures help the filament flow more consistently through the nozzle and reduce extrusion resistance.

Dry the Filament

• TPU is highly hygroscopic, meaning it absorbs moisture from the air rapidly.
• Wet TPU often produces bubbling, rough surfaces, poor layer adhesion, and inconsistent extrusion.
• Drying the filament before printing makes a major difference to print quality.
• Around 55 to 60°C for several hours is generally recommended, particularly in humid Australian conditions.
• For longer TPU prints, active drying during printing can help maintain consistency throughout the job.
• (see our filament storage guide).

Starting Your First TPU Print

For a first TPU project, keep it simple. Choose a small model with basic geometry, such as a phone grip, gasket, or simple flexible accessory, rather than attempting a large multi hour print immediately. Before printing, check that the filament path between the extruder and hotend is smooth and free from any gaps where the filament could catch or buckle. Feed the filament manually first to confirm it moves consistently through the system. Starting with a firmer 95A TPU and conservative print settings gives the best chance of success. Once the printer is behaving reliably, softer and more flexible materials become much easier to experiment with confidently.