Should I include fillets on my 3d printed parts?


A fillet is like a rounded corner but on the inside of the corner.

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Does it make a difference (structurally) to use fillets on a 3d printed part?


Posted 2019-06-15T20:37:43.283

Reputation: 2 090



If your part needs structural support, then the word is: absolutely. Fillets provide the added support when you need it. If your part has a meeting line which is sharp - 90° (or perpendicular), there is a natural stress riser in your design. This is a weak spot where a crack can form. If strength is needed and the fillet won't interfere with the design, it's definitely something you should include with your part.


Posted 2019-06-15T20:37:43.283

Reputation: 2 271

2Chamfers (flat corner cuts) are a better option for printability, unless the corner is in the XY plane. – Trish – 2019-06-16T18:46:48.400

1@Trish - chamfers are not really any more printable than a fillet In my (admittedly limited) experiance, and they still leave two stress points. – SiHa – 2019-06-18T10:40:15.303


Please check out Makers Muse on fillets & chamfers.

– Trish – 2019-06-18T11:38:22.477

@SiHa Fillets are less printable than chamfers (depending on the printing plane), please read this answer.

– 0scar – 2019-11-15T08:03:00.743


Fillets in X-Y plane (i.e. between two vertical surfaces) work great for 3D prints and increase the strength a lot. They usually also improve the print quality, because the print head can keep a constant speed in the curve instead of slowing down to a sharp corner.

However fillets that extend in Z direction (i.e. between a vertical and a horizontal surface) suffer from layer artifacts. Sometimes they can look worse than a sharp corner would. While they do still increase the strength significantly, they are not as strong as similarly sized fillets in X-Y plane are.


Posted 2019-06-15T20:37:43.283

Reputation: 241

So the nozzle can keep it's speed around corners better, and X-Y fillets are better than Z fillets. Kewlio. – user77232 – 2019-06-16T16:13:44.630