TPU 3D Printing: What Flexible Parts Are Good For
Feet, grips, straps and strain reliefs: the parts that should bend instead of crack, and the ones that should not be TPU at all.
TPU is the plastic to use when a part has to bend, squash or grip instead of holding its shape. It is a flexible material with roughly the firmness of hard rubber, and it stretches to several times its own length before it breaks. That makes it right for feet, bumpers, grips, straps and strain reliefs, and wrong for anything that has to stay stiff. Pick the job and see whether it is a TPU part.
What does the part have to do?
TPU for this?
Yes, ideal
Soft feet stop a stand or box sliding and protect the surface under it. Make them slightly larger than the hole they press into so they stay put.
Solid or nearly solid feet are firm; a little hollow inside makes them squash more.
TPU 90A against PLA Basic
Stretch before breaking
Knock along the layers
Knock across the layers
Bambu Lab’s data sheets: TPU 90A V1.0, PLA Basic V3.0. TPU has no heat-deflection figure; it bends rather than holding a rigid shape.
The number that explains it
TPU does not crack where a rigid plastic would. It bends, and comes back.
Against PLAPLA Basic stretches about 12% before it breaks. TPU 90A stretches about 650%, according to Bambu Lab’s data sheets.
What TPU is good for
- Feet and bumpers
- Non-slip feet for stands, boxes and lamps, and corner bumpers that protect walls and furniture.
- Grips and sleeves
- Handles, tool grips and sleeves that add a soft, sure hold to a rigid part.
- Strain reliefs
- The flexible boot where a cable meets a plug or a case, which bends thousands of times.
- Straps and loops
- Bands, loops and tethers that flex every day and stretch instead of snapping.
- Light seals
- Dust covers, splash guards and soft gaskets. Not for pressure, fuel or hot water.
Designing for TPU
- Thickness sets the feel
- Thin walls are soft and squashy; thick ones feel like a hard rubber wheel. The same file can feel very different at 1 mm and 3 mm.
- Infill sets the squish
- A solid TPU part is firm. Leaving some space inside makes it softer, which suits feet and grips.
- Undersize a fit
- A sleeve or plug that should grip needs to be a few tenths of a millimetre smaller than what it fits, so it stretches on.
- Avoid fine detail
- TPU prints slowly and soft walls blur small features. Keep text and edges bold.
The best TPU products are often half of something: a rigid stand in PLA with TPU feet, a PETG-CF mount with a TPU pad. Upload each part as its own file, pick the plastic for each, and build them into one product: the parts are fitted together before packing, with no assembly charge. For choosing the rigid half, see picking a plastic by the job, and for every material side by side, the heat and impact chart.
Ordering TPU parts
TPU prints much more slowly than PLA, so it is priced from its own slice: when you choose TPU for a part, the file is re-sliced in TPU and the price updates once that finishes. It costs a little more per gram than PLA as well. There are fewer colours of TPU on the rack than of PLA, so check the colour list when you order.
FAQ
Parts that have to flex, squash or grip: feet and bumpers, grips and sleeves, cable strain reliefs, straps and bands, and light dust or splash seals.
Tougher, not stiffer. In Bambu Lab’s data, TPU 90A takes several times the impact of PLA and stretches about 650% before breaking, against PLA’s 12%. But it bends under load, so it cannot hold a rigid shape.
The 90A is its Shore hardness: about as firm as hard rubber. Thin TPU walls are soft; thick ones are firm. Wall thickness and infill decide how a part feels.
It prints much more slowly, so a TPU part uses more printer time, and it costs a little more per gram.
Rigid where it holds, soft where it touches.
Build the TPU feet, grips or bumpers into one product with the rigid part they fit, choose assembly, and we fit them together before it ships, for $1 a part.
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