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TPU 3D Printing Guide: Ordering Flexible Parts

By Dynafabs

TPU 3D printing guide: choose the right shore hardness, walls and infill for flexible parts like grips, seals and bumpers, and order them right first time.

What TPU is and why it's different

TPU (thermoplastic polyurethane) is the rubbery one in the 3D printing family. Where PLA, PETG and ASA give you rigid parts, TPU gives you parts that bend, squash and spring back: bumpers, grips, seals, feet, straps and protective covers. If a part needs to absorb a knock or grip a surface rather than simply hold its shape, TPU is usually the answer.

That flexibility is also what makes it fussy to print. A soft filament behaves a bit like pushing a wet noodle through a straw, so it has to be printed slowly and carefully. This guide covers how to choose the right TPU and how to design and order flexible parts that come out the way you expect.

Shore hardness: pick the right squish

Flexible filaments are rated on the Shore hardness scale. On the A scale, a lower number is softer and a higher number is firmer. A few common grades:

• 95A is the standard flexible grade. It feels roughly like a typical flexible phone case: bendy but not floppy. It's the most printable and suits most jobs, from grips and cable protectors to gaskets and bumpers.
• 90A to 85A is noticeably squishier, which is handy for vibration dampers and soft seals, but harder to print and not supported on every machine.
• Hard TPU (rated on the D scale, such as 64D to 68D) is tough, bendy plastic rather than rubber. It's great for clips and impact-resistant parts that need some give.

Overture's TPU guide and the PrintPal TPU wiki both describe 95A as the go-to starting point, with softer grades being much harder to feed. If you're not sure, ask for 95A and describe how soft you want the part to feel.

How print settings change how flexible a part feels

Here's the bit most people don't expect: the material sets the feel of the plastic, but the print settings set the feel of the part. The same 95A TPU can make a soft, squashy bumper or a fairly stiff block.

• Walls: more walls make a stiffer, tougher part. Two or three walls keep things flexible.
• Infill: low infill (often 15 to 25%) leaves room to compress. SlicerGuide's TPU settings suggests gyroid infill in that range to keep parts flexible. Solid infill makes a dense, firm part.
• Wall thickness in your design: a thin TPU strap bends easily, while a thick one barely moves. If you need a hinge or bend zone, make it thinner on purpose.

So when you order, tell us how the part should behave: "should squash easily under a thumb" or "should flex but hold its shape" is much more useful than a percentage. We'll pick walls and infill to match. Our layer height, infill and walls guide explains these settings in more detail.

Why TPU prints are slower (and sometimes cost more)

TPU has to be printed slowly. The guides above put typical 95A print speeds at around 20 to 40 mm/s, much slower than rigid filaments on a modern printer, because pushing too fast makes the soft filament buckle in the extruder. TPU also needs to be dried before printing, as moisture causes stringing and rough surfaces.

In practice that means a TPU part usually takes longer on the printer than the same part in PLA or PETG. If timing matters, mention your deadline when you request a quote.

Designing parts for TPU

A few design habits make flexible prints much more reliable:

• Avoid tiny, delicate details. Fine points and thin pins wobble as they print and can come out soft or stringy.
• Minimise overhangs and supports. Supports bond firmly to TPU and are harder to remove cleanly, so design parts that sit flat where you can. Our print orientation guide covers how orientation affects finish and strength.
• Allow for stretch in fits. A TPU sleeve or cover can be made slightly snug so it grips, which isn't possible with rigid plastic. For parts that mate with rigid ones, our tolerances and clearance guide is a good starting point.
• Expect a matte, slightly soft-edged finish. TPU doesn't take crisp, sharp corners in the way PLA does.

TPU or something else?

TPU isn't always the right flexible choice:

• If the part needs to be rigid but tough, PETG or a nylon may be better. See our material comparison guide.
• If it needs to survive heat or long sun exposure, check our outdoor materials guide and mention the conditions when you order.
• If you need a flexible part and a rigid part that fit together, it's often simplest to print them separately in TPU and PETG and assemble them.

FAQ

Is TPU waterproof? TPU itself doesn't absorb water once printed, but a printed part has layer lines, so a watertight seal depends on the design and settings. Tell us if the part needs to hold or keep out water.

Can you print soft TPU, like 85A? Softer grades are harder to print and not every machine supports them. Ask when you request a quote and describe the softness you need.

Can TPU be painted? It can be, but because it flexes, paint can crack. Choosing a coloured filament is usually more durable.

What's TPU good for? Bumpers, feet, grips, gaskets, cable protectors, straps and protective covers are all classic TPU jobs.

Order your flexible parts

Got a part that needs to bend, grip or cushion? Send us your file, tell us how soft it should feel and where it'll be used, and get your Dynafabs quote. We'll recommend the right TPU and settings for the job.

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