Invalid geometry

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kisolre
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Re: Invalid geometry

Post by kisolre »

perot wrote: Sun Jan 23, 2022 7:26 pm I also noticed another way of avoiding the problem,
Just avoid unnecessary refinements. Setting Refine=False to the last cut does not generate the error.
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thomas-neemann
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Re: Invalid geometry

Post by thomas-neemann »

perot wrote: Sun Jan 23, 2022 4:00 pm What's wrong with this exceeding simple geometry?
Hi Peter

another workaround. export as scg and import
problem-Cut001.csg
(641 Bytes) Downloaded 17 times
Gruß Dipl.-Ing. (FH) Thomas Neemann

https://www.youtube.com/@thomasneemann5 ... ry=freecad
perot
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Re: Invalid geometry

Post by perot »

heda wrote: Sun Jan 23, 2022 6:19 pm you probably do not need to remodel as such, your model starts working when the angle is 94 and above.
You were faster than me.

The source of that number is clear: At 93.82° the seam is exactly at the location where the cut happens. Beyond that it is cut away, along with the problem.

I indeed now rotated the base part in my full model (it is actually a revolved sketch) by 180°, and magically everything is fine. I'd still like to know why.

Cheers Peter
kisolre
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Re: Invalid geometry

Post by kisolre »

perot wrote: Sun Jan 23, 2022 8:27 pm I'd still like to know why.
And for the third time I will repeat that: OCC does not properly refine shapes every time. There were probably tree recent examples with such cylindrical surfaces where Refine=True creates bad geometry. Not sure if FreeCAD devs can do something to fix that.
perot
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Re: Invalid geometry

Post by perot »

kisolre wrote: Sun Jan 23, 2022 10:35 pm
perot wrote: Sun Jan 23, 2022 8:27 pm I'd still like to know why.
And for the third time I will repeat that: OCC does not properly refine shapes every time.
You're obviously not a particularly curious person. I am. For me, this does not answer my question.

Cheers Peter
kisolre
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Re: Invalid geometry

Post by kisolre »

perot wrote: Mon Jan 24, 2022 2:59 pm You're obviously not a particularly curious person. I am. For me, this does not answer my question.
How can I be curious about the things that I already know when no contradictory information is provided?
Do you know what Refining does? I suspect not. Do you want to to know and how does that affect your model? Is this not the point of the OP?
When refining OCC kernel tries to match adjacent faces which lay on the same geometric surface and describe them as one. And fails to properly do so. There were a number of recent topics where that fails with the parts of the same starting cylindrical surface. I don't know if FreeCAD can do something about that except to file bug reports to OCC (a lengthy and not easy process) and hope this will get fixed in the future.
domad
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Re: Invalid geometry

Post by domad »

Hi perot, greetings to the Community!
No problem found, except if I exaggerate in the size of the bevel, in the attached image the bevel is 10mm in diameter and 5mm in depth.
I have no problems even with bevels of equal length.
Attachments
problem.FCStd
(48.61 KiB) Downloaded 17 times
Invalid_geometry_no_problem.png
Invalid_geometry_no_problem.png (220.72 KiB) Viewed 727 times
TheMarkster
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Re: Invalid geometry

Post by TheMarkster »

domad wrote: Mon Jan 24, 2022 5:12 pm Hi perot, greetings to the Community!
No problem found, except if I exaggerate in the size of the bevel, in the attached image the bevel is 10mm in diameter and 5mm in depth.
I have no problems even with bevels of equal length.
The original issue was without any chamfer. The chamfer is a way to fix the issue. In my experiments only when the chamfer is too small does it not work (less than 0.011 mm). But I think setting refine to false is a better solution because it does not modify the geometry, unless of course, you actually want the chamfer.
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