How to Print with TPU:
The Complete Flexible Filament Guide

What Is TPU and Why Does It Matter?

TPU stands for Thermoplastic Polyurethane — a class of flexible, rubber-like material that bridges the gap between hard plastics and silicone. Unlike PLA, PETG, or ABS, TPU can be bent, stretched, and compressed without breaking. Parts return to their original shape after deformation, which is exactly what you need for phone cases, cable strain reliefs, flexible hinges, gaskets, shoe insoles, and a hundred other applications that rigid filaments can't handle.

The key property that defines TPU grades is Shore hardness, measured on the A scale. The higher the number, the stiffer the material. Here's what the common grades mean in practice:

For most people, 95A is the right starting point. It's flexible enough for the most common applications, stiff enough to print reliably on a properly set up direct drive printer, and widely available from most filament manufacturers. This guide focuses on 95A but notes where softer grades need different treatment.

Hardware: Direct Drive Is Non-Negotiable

The single most important factor in TPU printing is your extruder type. TPU's elasticity works against the retraction mechanism in Bowden setups — the filament compresses inside the PTFE tube instead of retracting cleanly, causing inconsistent extrusion, grinding, and eventual clogs.

All Bambu Lab printers use direct drive extruders, which makes them well-suited for TPU. The Prusa MK4, Prusa Core One, Voron, and most modern CoreXY machines also use direct drive. If you have a stock Ender 3 or similar Bowden machine, a direct drive conversion kit (the Micro Swiss NG is a popular option) makes a significant difference for flexible filaments.

Beyond the extruder type, make sure your PTFE tube (if any is used) reaches all the way to the nozzle. Gaps in the hot end where flexible filament can buckle are a common source of jams. All-metal hot ends without PTFE reaching the nozzle are fine, but they require higher minimum temperatures to avoid sticking.

Speed — The Single Most Important Setting

If there is one rule for printing TPU, it's this: print slowly. TPU's elasticity means it takes slightly longer to move through the extruder than rigid filaments — the elastic spring-back in the filament path adds a small delay between extruder motion and material exiting the nozzle. At high speeds, the extruder outruns the melt, causing under-extrusion.

The numbers above are starting points for 95A TPU on a direct drive. Softer grades (87A, 83A) need the lower end of each range — sometimes even lower. On your first print, err on the side of too slow. A 2-hour print at 20mm/s is better than a failed print at 50mm/s.

Once you have a successful print, increase speed in 5mm/s increments on subsequent prints, watching for surface roughness, gaps in walls, or clicking from the extruder (signs of under-extrusion). Most 95A TPU finds a comfortable ceiling around 35–40mm/s on a well-tuned direct drive.

Temperature Settings

Most consumer TPU grades print between 220°C and 240°C. The general rule: start at the lower end of your filament's recommended range. Higher temperatures make TPU more fluid, which improves layer adhesion but dramatically increases stringing and oozing — two issues flexible filaments are already prone to.

TPU adheres well to most print surfaces. PEI spring steel sheets work well; so does smooth glass with a light glue stick coating. On Bambu printers, the textured PEI plate gives excellent TPU adhesion and easy part removal — the flexible filament pops off cleanly once cooled. Don't use hairspray or adhesive on textured PEI with TPU; adhesion is already strong and the combination can bond too well.

Retraction — Less Is More

This is where TPU completely breaks from the rules for rigid filaments. High retraction that works perfectly for PLA will cause grinding, inconsistent extrusion, and failed prints with TPU. The elastic nature of the filament means it compresses under retraction force rather than cleanly pulling back — the extruder motor strains against the filament spring, loses grip, and grinds the surface.

The most effective anti-stringing strategy for TPU is combing (avoid crossing perimeters), which routes travel moves through the interior of the model where any ooze is invisible. This sidesteps the retraction problem entirely for most geometry. Combine combing with minimal retraction and you'll get acceptable stringing performance without risking extruder grinding.

For Bowden setups, use 2–3mm retraction at most, accept more stringing than direct drive, and lean heavily on combing. Some Bowden users have better results with zero retraction entirely, relying only on combing and wiping.

Common Problems and Fixes

Extruder grinding / clicking

The most common TPU failure. The extruder motor is working harder than the filament can flow through the hot end, causing the drive gear to chew into the filament. Fix: reduce print speed by 5–10mm/s, increase temperature by 5°C, and check that retraction isn't too high (over 1mm on direct drive). Also check that your PTFE pathway has no gaps where the filament can buckle.

Spaghetti in the tube (Bowden jams)

On Bowden setups, TPU can buckle and curl inside the PTFE tube instead of moving forward. This often happens at the coupler connecting the tube to the extruder. Fix: use a proper push-fit coupler with no gap, reduce speed significantly, and reduce retraction to near-zero. If this keeps happening, a direct drive conversion is the real solution.

Poor bed adhesion / warping

TPU doesn't warp like ABS, but it can peel if bed temperature is too low or the surface isn't clean. Clean your build plate with IPA, ensure the bed is at 35–45°C, and slow down your first layer. On glass beds, a thin layer of glue stick helps. On Bambu's textured PEI, adhesion is usually strong without any treatment.

Excessive stringing

TPU strings more than rigid filaments — this is normal to some degree. To minimize it: enable combing, reduce print temperature by 5°C, increase travel speed, and use minimal retraction with a wipe move. Wet TPU strings dramatically more — if you've had the spool open for more than a few days, dry it at 45–50°C for 4–6 hours before printing.

Under-extrusion mid-print

Usually a speed issue. The extruder is outrunning the melt rate, and the elastic filament is absorbing the mismatch before finally slipping. Fix: reduce outer wall speed, increase temperature by 5°C, and verify your volumetric flow limit if using OrcaSlicer. Sometimes a partial clog is the issue — do a cold pull to clear any residue from previous materials.

Bambu Lab & AMS Tips

Bambu Lab printers are some of the best consumer machines for TPU thanks to their direct drive extruder and rigidity. However, the AMS (Automatic Material System) is not designed for flexible filaments and cannot reliably transport TPU through its tubes and buffer mechanism.

To use TPU on a Bambu Lab X1C or P1S:

1. Place your TPU spool on the external spool holder (or on a dry box next to the printer).
2. Thread the filament through the external spool slot — there's a dedicated path that bypasses the AMS entirely.
3. In Bambu Studio, select the external spool as your filament source and choose TPU as the material type.
4. The printer will use its pre-set TPU profile, which already has appropriate speed and temperature limits.

For the Bambu Lab A1 Mini, the AMS Lite has a slightly different mechanism than the full AMS — but TPU still cannot reliably run through it. The same external spool approach applies.

Bambu's built-in TPU profiles are well-tuned for Bambu Lab's own TPU 95A but generally work with third-party 95A too. If using a different brand, check the recommended temperature range and adjust accordingly within Bambu Studio's custom material settings.

Best TPU Filaments to Buy in 2026

TPU quality varies more than PLA quality — diameter consistency matters especially for flexible filaments because inconsistent diameter creates erratic extrusion that's very hard to tune out. These are the brands that have consistently performed well in testing: