How to print with TPU Filament?

TPU (thermoplastic polyurethane) is one of the most versatile filaments you can print with — flexible, food safe, wear-resistant, and available in multiple Shore hardness grades to suit different applications. It is also one of the trickiest to master. This guide covers everything you need to get reliable, high-quality results with Eolas Prints TPU flexible filament.

Understanding Shore Hardness

Before choosing your settings, it is essential to understand what Shore hardness means — because Eolas Prints makes three different TPU grades with meaningfully different printing requirements.

Product	Shore Hardness	Feel	Best For
TPU Flex D53	Shore D53	Soft — like a rubber eraser	Wearables, prosthetics, soft grips, skin-contact parts
TPU Flex 93A	Shore 93A	Medium-soft — like a car tyre	Phone cases, gaskets, seals, food-safe items, general flexible parts
TPU Flex D60 UV	Shore D60	Firmer — like a hard rubber heel	Outdoor parts, UV-exposed components, high-wear applications

The softer the grade, the more care is needed during printing. D53 is the most challenging; D60 UV is the most forgiving.

Recommended Print Settings

Parameter	D53 (soft)	93A (medium)	D60 UV (firm)
Nozzle temperature	220–230°C	220–235°C	225–240°C
Bed temperature	50–60°C	50–60°C	50–60°C
Print speed	10–20 mm/s	15–30 mm/s	20–40 mm/s
Retraction distance	0–0.5mm	0.5–1mm	1–2mm
Retraction speed	20–25 mm/s	25–30 mm/s	25–35 mm/s
Cooling fan	50–70%	50–80%	60–80%
Extruder	Direct drive only	Direct drive strongly recommended	Direct drive or short Bowden

The Most Important Rule: Print Slowly

TPU jams are almost always caused by printing too fast. Unlike rigid filaments, TPU is flexible — if the print head moves faster than the material can feed, the filament buckles in the extruder path rather than advancing into the nozzle. This causes a tangle above the drive gear that can be difficult to clear.

Start at the minimum speed for your grade. Once you have consistent extrusion with no jams or gaps, increase speed by 5 mm/s at a time until you find the reliable ceiling for your specific printer and extruder.

Direct Drive vs Bowden: What You Need to Know

Direct drive extruders are required for D53 and strongly recommended for 93A. The motor drives the filament directly into the hot end with minimal unsupported path length, which is what keeps flexible filament from buckling.

Bowden extruders are only reliable with the firmest grade, D60 UV — and even then, only with a short tube (under 400mm), tight PTFE fittings with no gaps, and speeds kept below 30 mm/s. Attempting D53 or 93A in a Bowden setup will result in jams in most cases.

Bambu Lab printers use a short-path direct drive system and handle TPU very well. However, the AMS (Automatic Material System) is not compatible with flexible TPU — load TPU from the external spool holder only. The AMS hub and PTFE path are too long and narrow for flexible filament.

Drying TPU Before Printing

TPU is highly hygroscopic — it absorbs moisture from the air rapidly, and printing wet TPU causes stringing, surface bubbling, popping sounds during extrusion, and weak layer adhesion. If your spool has been open for more than a few days, dry it before printing.

• Dry at 50–60°C for 4–8 hours in a filament dryer or low-temperature oven
• Do not exceed 65°C — soft TPU grades can deform at higher temperatures
• Store in a sealed container or dry box with desiccant between print sessions
• A filament dry box that feeds directly to the printer while printing is ideal for TPU

Bed Adhesion

TPU adheres well to most surfaces with a heated bed. PEI sheets work well — TPU grips firmly when hot and releases cleanly when cool. Glass with a thin layer of glue stick also works reliably. Avoid maximum bed temperatures above 60°C, which can make TPU bond too aggressively to PEI.

A brim (3–5mm) helps prevent corner lifting on larger parts. For very soft grades (D53), a raft can provide a more stable printing surface for the first layers.

Common Issues and Fixes

Clogging or Jamming

Almost always caused by printing too fast or by a gap in the filament path. Reduce speed to the minimum for your grade, disable retraction or reduce to 0.5mm, ensure all PTFE tube connections are tight with no gaps where flexible filament can buckle, and ensure you are using a direct drive extruder for soft grades.

Stringing

TPU strings more than rigid filaments. Reduce retraction distance (keep it under 1mm for 93A, under 0.5mm for D53), increase travel speed, enable combing mode in your slicer to avoid crossing perimeters during travel, and ensure the filament is dry. Increasing temperature slightly can also help with stringing if the material is running cold.

Surface Bubbling or Popping

This is wet filament. Dry at 50–60°C for 4–8 hours and retry.

Weak Layer Adhesion

Increase nozzle temperature by 5°C, reduce print speed, and reduce cooling fan slightly. TPU needs adequate heat for good layer bonding.

Post-Processing TPU

TPU is difficult to sand due to its flexibility, but can be trimmed cleanly with sharp scissors or a scalpel. It accepts flexible adhesives well — use TPU-compatible contact cement or flexible super glue for bonding parts. Standard acrylic paints work on TPU with a flexible primer applied first; avoid rigid paints which will crack when the part flexes.

Filament Storage

Store all TPU spools in sealed containers or resealable bags with silica gel desiccant. In humid climates, even a few hours of exposure can degrade print quality. A dry box that feeds directly to the printer during printing is the best long-term solution for frequent TPU users.

Eolas Prints TPU Range

• TPU Flex D53 — Shore D53, the softest grade. Skin safe, food safe. Ideal for wearables, prosthetics, orthopaedic supports, and soft-touch products. Direct drive only.
• TPU Flex 93A — Shore 93A, the most versatile grade. Food safe, skin safe. Ideal for phone cases, gaskets, seals, kitchen accessories, and functional flexible parts.
• TPU Flex D60 UV — Shore D60, UV-stabilised. The firmest and most outdoor-capable grade. Hydrolysis resistant, microbial resistant. Ideal for garden, marine, and automotive applications.
• TPU Transition — Shore 93A, gradient colour effect. Made sustainably from manufacturing offcuts. Ideal for artistic and decorative flexible prints.