Creating planarsrf from 2 concentric curves

Hi Everyone,

I am trying to create a surface out of two concentric circles. I want this surface to be between the two circles. Sometimes it works, and other times it doesn’t. Actually, I don’t understand what is the difference between the two and why not always I am able to create the surface between the two. I am sure that I am missing something here. I have read other posts but still cannot solve it. These are two images for both cases:

Thank you so much for your guidance to solve this issue.

Might help if you upload a file with both cases (not working & working) curves in it.

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It’s a good idea. I uploaded a rhino file of these concentric circles. Please zoom in on the origin as these structures are small, at the scale of micrometers (µm).
Planarsrf for Concentric Circles.3dm (1013.7 KB)

Hi @Sam24
Those curves are at the same size as your file tolerance settings, which will not work. You tolerance should be set to at least 1/10 of your smallest feature, in this case that would be 0.0001mm. Then it will work. If you are often working on features this small, it might be a good idea to make your own template file with the tolerance cranked up. Beware that such tight tolerances will increase file complexity on larger objects. What are you modeling that requires features THAT small? :grimacing:
HTH, Jakob

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You can also model directly in microns to avoid having to use such tight tolerances…


Hi @Normand
Thanks a lot! This solved my problem. Much appreciated. These designs are to be created by stereolithography. That’s why I am working with such small scales!

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