TPU is the standard flexible filament for FDM printing. Shore hardness explained, direct drive requirement, specific print settings, and what it’s actually good for. If you’ve never printed flexible before, this is where to start.
TPU (thermoplastic polyurethane) is the flexible filament you reach for when a print needs to bend, compress, and return to shape. Where PLA and PETG are rigid, TPU behaves more like rubber. It’s impact-resistant, abrasion-resistant, and can handle repeated flex without cracking.
The practical catch: TPU needs a direct drive extruder to print reliably, it prints slowly, and it requires more dialling in than PLA. The flexibility that makes it useful is also what makes it want to buckle inside a Bowden tube. Get the setup right and it’s a capable material with applications PLA and PETG simply can’t cover.
Shore A is the hardness scale for flexible materials. Lower number means softer. The two most common TPU formulations for FDM printing are 95A and 87A.
95A TPU is firm enough that thin walls hold their shape, but the material flexes clearly under finger pressure. Most phone case STL files are designed with 95A in mind. It’s the easiest TPU to print and the right starting point for most applications.
87A TPU is noticeably softer and more rubber-like. Better for grips, wearables, and anti-vibration applications where you want genuine give. Harder to print because the extra softness makes it more prone to buckling between the drive gear and hot end. Requires slower speeds and a well-tuned extruder.
There are also harder formulations like 98A that print almost like rigid filament but with just enough flex to resist cracking on impact. Useful for parts that need to be tough rather than soft.
TPU needs a direct drive extruder. On a Bowden setup, the PTFE tube between the drive gear and the hot end gives the soft filament room to compress and buckle under extrusion pressure. The result is inconsistent flow, blobs, and eventually the drive gear grinding a groove into the filament.
Direct drive systems like those on the Bambu A1, A1 Mini, P1S, and X1C have the drive gear positioned directly above the hot end with no tube gap. The filament goes from gear to melt zone with no opportunity to flex sideways. This is why these printers handle TPU reliably where older Bowden printers like the original Ender 3 struggle.
If you’re running a Bowden printer and determined to print TPU: reduce speed to 15-20mm/s, disable retraction entirely, and accept that results will be inconsistent. Direct drive is the real fix.
Nozzle: 220-240°C. Start at 225°C for 95A. Softer formulations (87A) often benefit from 230-235°C for better flow.
Bed: 40-60°C. TPU sticks well to PEI sheets at 50°C without adhesive. Let the part cool fully before removing it. Hot TPU is very soft and will deform if pulled off early.
Speed: 20-30mm/s. This is the most important setting. TPU at high speed causes inconsistent flow, stringing, and layer separation. 25mm/s is a reliable working speed for 95A on a well-tuned direct drive system.
Retraction: 0.5-1.5mm for direct drive. Very low. TPU doesn’t need much retraction and over-retraction causes air gaps in the extrusion that show as holes in flexible walls.
Cooling: reduce fan speed or disable for the first 3-4 layers. TPU benefits from staying warm between layers for good adhesion, especially on the first few.
Layer height: 0.16-0.24mm. TPU doesn’t gain much from very fine layer heights. The flexibility of the material means fine layer lines are less visible in use anyway.
Phone cases are the most common TPU application. Impact absorption works because the flexible material deforms on impact and distributes the force rather than transmitting it directly to the glass. Standard PLA phone cases crack on drop because the rigid material has nowhere to go.
Gaskets and seals where TPU compresses to fill gaps and maintain contact. Dust covers, port protectors, and equipment enclosure seals all work well in TPU.
Grips and handles on tools, accessories, or props. TPU’s combination of texture, grip, and give makes it more functional than any rigid plastic for anything held in the hand.
Flexible joints and living hinges in assemblies. Cable guides, snap-fit clips that need to flex for assembly, and hinges where you want movement without a separate pin.
Anti-vibration pads under 3D printers, speakers, and equipment. TPU absorbs vibration that rigid feet transmit directly to the surface.
TPU is not a replacement for PLA or PETG in structural applications. It deforms under sustained load. A bracket printed in TPU will creep and deflect over time. Use it where flexibility is the point, not where rigidity is required.
Dry your filament before printing. TPU absorbs moisture and wet TPU produces bubbly, inconsistent extrusion that looks like the nozzle is spitting. Dry at 50°C for 4-6 hours in a filament dryer or food dehydrator before a print session. Store TPU in a sealed bag with desiccant.
Avoid supports where possible. TPU supports are very difficult to remove cleanly because the material stretches rather than breaking. Design files to print flat or orient them to minimise overhangs. If supports are unavoidable, use a different material for the support interface layer and set a large interface gap.
Print a purge line before the model. TPU needs 5-10cm of consistent extrusion to establish stable flow before it hits the actual model. Most slicers have a purge line option; use it.
Keep speed consistent throughout the print. Speed changes mid-print cause flow inconsistency with TPU. Set a uniform speed and leave it. Don’t use adaptive layer height features that change print speed dynamically.
We use eSUN TPU for flexible parts that require documented settings. Shore 95A, 225°C nozzle, 50°C bed, 25mm/s. It prints consistently across spools and doesn’t give surprises between batches, which matters when you’re verifying settings before publishing them.
eSUN TPU is available through the eSUN Official Store.
Disclosure: the eSUN link above is an affiliate link. If you purchase through it, we earn a small commission at no cost to you. We only recommend products we use ourselves.
Most OreKo models are designed for PLA. When flexibility or heat resistance matters for a specific application, product pages note the alternative material and updated settings.