Fillet on a solid fails

Hello everyone, I am trying to make a fillet on the highlighted edge in the image. I attach the BREP file. I try with fillet of 1 mm.
Any ideas what is wrong on my site? Is it just a limitation of the fillet that this case cannot be handled? I tried in solidworks and parasolid makes expected fillet there.

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Mikhail Sazonov's picture

Fillet is built on this edge using the following draw commands:

restore test.brep a
explode a e
fillet r a 1 a_12

The operation does not report any errors. However, the result shape is invalid (see the attached picture). Please feel free to report a bug on OCCT bug tracker.

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Kostadin Vrantzaliev's picture

Thank you for this investigation. It is strange that this example is very typical especially for mechanical parts. I will report it.

baverman's picture

As for 2024 a general trick is to make sure a fillet could continue with same geometry. For your case box should be a little bit larger and cut/split to needed dimensions later. image1: fillet with a lager box, image2: part with final dimensions.

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Kostadin Vrantzaliev's picture

I see your point, but if you take any other packages based on Parasolid, there is no such issue - the fillet works perfectly without making the other shape larger.

baverman's picture

I'm not a dev :) I've just searched for fillet issues and saw your topic for which I know a workaround. I agree OCCT has rough edges around filleting (sorry for pun) and it could be extremely annoying. But there is no other powerful BREP kernel allowing to use cad-as-code approach. Personally I think this very filleting case is quite hard to fix, I bet parasolid devs had hard times to make it work.

Kostadin Vrantzaliev's picture

I totally agree for all that you say.