How to 3D Print TPU and Flexible Filaments — The Complete Guide

TPU (Thermoplastic Polyurethane) is the material you reach for when your print needs to bend, flex, compress, or absorb impact. Phone cases, drone bumpers, gaskets, watch bands, shoe insoles, and vibration dampeners are all perfect TPU applications. But TPU has a reputation for being difficult, and that reputation is earned — flexible filament behaves completely differently from rigid materials like PLA or PETG.

The good news is that with the right settings and some understanding of why TPU behaves the way it does, you can print it reliably. This guide covers everything you need to know, from extruder type to slicer settings to troubleshooting the most common failures.

Understanding TPU Hardness: Shore A Ratings

Not all TPU is the same. The flexibility of TPU is measured on the Shore A hardness scale. The lower the number, the softer and more flexible the material:

| Shore A Rating | Flexibility | Printability | Example | |---------------|-------------|--------------|---------| | 85A | Very soft, rubber-like | Difficult — direct drive only | NinjaTek Chinchilla | | 95A | Flexible, like a car tire | Moderate — most common TPU | NinjaTek NinjaFlex, Overture TPU | | 98A | Semi-flexible | Easier — works on most setups | Polymaker PolyFlex | | 100A | Slightly flexible | Easiest TPU to print | SainSmart TPU |

For your first TPU print, start with 95A TPU. It is the most common hardness and hits the sweet spot between flexibility and printability. Anything softer than 90A requires a direct drive extruder and extremely slow speeds.

Direct Drive vs Bowden: Which Extruder for TPU?

The extruder type on your printer is the single biggest factor determining whether TPU printing will be easy or miserable. According to 3DISM's comparison of direct drive and Bowden extruders, the filament path length is the critical difference.

Direct Drive Extruders

A direct drive extruder sits directly on top of the hotend, giving a filament path of just 20–30 mm from the drive gear to the nozzle. This short path means:

• The filament has almost no room to buckle or compress
• Responsive extrusion control with minimal lag
• Retraction works reliably at short distances
• Softer TPU (85A–90A) can be printed

Printers with direct drive: Prusa MK4S, Bambu Lab P1S/X1C/A1, Creality Ender 3 V3, Creality K1, Voron

Bowden Extruders

A Bowden extruder is mounted on the frame, pushing filament through a PTFE tube that can be 400–600 mm long. This is a problem for flexible materials because:

• The filament compresses and stretches inside the tube
• Extrusion response is delayed and inconsistent
• Retraction is unreliable (the filament just flexes instead of pulling back)
• Softer TPU will jam inside the tube

Can you print TPU on a Bowden setup? Yes, but only stiffer TPU (95A and above), at very slow speeds (15–20 mm/s), and with retraction disabled. It will work but requires more patience and produces more stringing.

As NozzleNerd's TPU speed guide explains, the Bowden tube must be perfectly secured with zero gaps at both ends to prevent filament from buckling at the fittings.

TPU Slicer Settings: Direct Drive

Here is a reliable starting profile for 95A TPU on a direct drive printer:

• Nozzle Temperature: 220–235°C (start at 225°C)
• Bed Temperature: 50–60°C
• Print Speed (walls): 25–35 mm/s
• Print Speed (infill): 35–45 mm/s
• Travel Speed: 120–150 mm/s
• First Layer Speed: 15–20 mm/s
• Layer Height: 0.2 mm
• Initial Layer Height: 0.24 mm
• Infill Density: 10–30% (lower = more flexible)
• Infill Pattern: Gyroid (excellent for flexible parts)
• Wall Count: 3–4
• Top/Bottom Layers: 5
• Retraction Distance: 0.5–2 mm
• Retraction Speed: 25 mm/s
• Cooling Fan: 50–80%
• Build Plate Adhesion: Brim
• Combing Mode: Within Infill

TPU Slicer Settings: Bowden

If you are printing TPU on a Bowden printer, use these adjusted settings:

• Nozzle Temperature: 225–240°C
• Bed Temperature: 50–60°C
• Print Speed: 15–20 mm/s (everything — walls, infill, all of it)
• Travel Speed: 80–100 mm/s
• First Layer Speed: 10–15 mm/s
• Retraction: OFF (disable entirely)
• Combing Mode: All (to minimize travel moves over open space)
• Z Hop: Enabled, 0.4 mm (helps avoid nozzle dragging since retraction is off)

The critical difference is speed. On a Bowden setup, you must print slowly enough that the flexible filament is never under enough pressure to buckle inside the tube.

How Infill Affects Flexibility

With TPU, infill is not just about strength — it directly controls how flexible the finished part is.

| Infill Density | Behavior | |---------------|----------| | 0–10% | Maximum flexibility, almost no internal structure | | 15–20% | Flexible with some bounce-back | | 30–40% | Semi-rigid, good for protective cases | | 50%+ | Fairly rigid, but still impact-resistant | | 100% | Solid, minimal flex — like a hard rubber |

Gyroid infill is the best pattern for TPU because it provides uniform flexibility in all directions. Grid and line infill create directional stiffness, meaning the part will flex differently depending on which way you bend it. Gyroid avoids this entirely.

Common TPU Failures and Fixes

1. Filament Grinding

What it looks like: The drive gear chews into the filament, creating a flat spot or notch, and extrusion stops.

Cause: Printing too fast or with too much retraction. The drive gear cannot push the flexible filament fast enough and grinds against it instead.

Fix: Reduce print speed by 10 mm/s. Reduce retraction distance to 1 mm or disable it. Loosen the extruder tension slightly if your printer has an adjustable idler.

2. Filament Wrapping Around the Drive Gear

What it looks like: The filament escapes the path between the drive gear and the PTFE tube, wrapping around the gear.

Cause: A gap in the filament path near the extruder. Flexible filament will find any gap and exploit it.

Fix: Ensure there are no gaps between the drive gear and the PTFE tube inlet. On Bowden setups, push the PTFE tube firmly into the coupler and cut it flat. Some users print small guide pieces to close gaps in their extruder assembly.

3. Stringing

What it looks like: Thin threads of TPU between separate parts of the model.

Cause: TPU is naturally stringy because of its elastic properties. The filament stretches instead of breaking cleanly during travel moves.

Fix: Enable combing mode to keep travel moves within the print boundary. If using retraction, keep it at 0.5–1 mm on direct drive. Increase travel speed to 150 mm/s so the nozzle moves quickly between points. Lower the nozzle temperature by 5°C.

4. Under-Extrusion and Gaps

What it looks like: Thin walls, visible gaps between lines, poor layer adhesion.

Cause: The filament is compressing in the path rather than extruding consistently. This is worse on Bowden setups.

Fix: Slow down the print speed. Increase the flow rate by 5–10%. Make sure your nozzle temperature is high enough — under-extrusion at the right speed usually means the filament is not melting fast enough.

5. Elephant Foot

What it looks like: The first layer is wider than the rest of the print, creating a bulge at the base.

Cause: The nozzle is too close to the bed, or bed temperature is too high, causing the soft first layer to squish outward.

Fix: Raise the Z offset slightly. Lower the bed temperature to 50°C. Reduce the initial layer flow to 95%.

Best TPU Brands in 2026

Here are the top TPU filaments based on printability, flexibility, and consistency:

| Brand | Product | Shore A | Price (1 kg) | Notes | |-------|---------|---------|-------------|-------| | NinjaTek | NinjaFlex | 85A | ~$46 | The original, very flexible, premium | | Overture | TPU 95A | 95A | ~$22 | Excellent value, consistent quality | | Polymaker | PolyFlex TPU95 | 95A | ~$30 | Tight tolerance, works on most printers | | SainSmart | TPU | 95A | ~$26 | Budget pick, reliable | | eSUN | eTPU-95A | 95A | ~$25 | Good all-around, widely available | | Bambu Lab | TPU 95A HF | 95A | ~$30 | Optimized for Bambu printers |

For most people, Overture TPU 95A offers the best combination of price and printability. If you want maximum flexibility for artistic or wearable projects, NinjaTek NinjaFlex at 85A is the gold standard, but it demands a direct drive extruder and very slow speeds.

Overture's TPU printing guide has a solid walkthrough of their recommended settings for different printer types.

TPU Storage and Drying

TPU is hygroscopic — it absorbs moisture from the air. Wet TPU causes:

• Popping and sizzling sounds during printing
• Visible bubbles in the extruded lines
• Poor surface quality and rough texture
• Reduced layer adhesion

Drying temperatures: Dry TPU at 50–55°C for 4–6 hours. A dedicated filament dryer works best, but an oven set to its lowest temperature with the door cracked open can work in a pinch.

Storage: Keep TPU in a sealed bag with desiccant when not in use. Better yet, print directly from a dry box. TPU absorbs moisture faster than PLA, so leaving it out overnight in a humid environment can noticeably affect print quality.

Practical TPU Projects

If you are wondering what to print with TPU, here are some practical applications:

• Phone cases: Flexible, shock-absorbing, custom-fit
• Watch bands: Comfortable and durable
• Gaskets and seals: Replace worn rubber parts
• Vibration dampeners: Printer feet, motor mounts
• Drone bumpers: Absorb crash impacts
• Hinges: Living hinges that flex thousands of times
• Grips: Tool handles, controller grips
• Shoe insoles: Custom orthotics (consult a professional for medical use)

Search for TPU-compatible models on 3DSearch to find designs optimized for flexible filament across all major model repositories.

Advanced Tips

Printing TPU Fast (Direct Drive Only)

Once you are comfortable with the basics, you can push direct drive TPU speeds higher:

1. Use a hardened steel or CHT nozzle for better flow
2. Increase nozzle temperature to 235–240°C
3. Gradually increase speed to 40–50 mm/s
4. Monitor for under-extrusion and back off if it appears

Some users on high-flow printers like the Bambu Lab X1 Carbon report successful TPU prints at 60+ mm/s, but this is not typical and requires careful tuning.

Multi-Material with TPU

Combining TPU with PLA or PETG in a single print opens up interesting possibilities — rigid structures with flexible joints, for example. The Bambu Lab AMS and Prusa MMU3 both support TPU, though multi-material TPU printing requires careful retraction tuning to avoid jams at the toolchange point.

Final Thoughts

TPU printing is not as intimidating as it seems. The rules are simple: use a direct drive extruder if possible, print slow, keep retraction minimal, and choose the right Shore A hardness for your project. Start with 95A TPU at 25 mm/s, get a successful print, and then adjust from there.

The flexibility that TPU offers opens up an entire category of prints that rigid filaments simply cannot achieve. Once you have it dialed in, you will find yourself reaching for TPU far more often than you expected.

Find flexible-ready models at 3DSearch and start experimenting.

Happy printing!