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Why does this mirrored loft, when thickened, have strange geometry on one side?
rehevkor5
Member Posts: 13 ✭
To view the relevant surface directly in Onshape, open this part studio then click "Comments" in the left bar, and in the first comment, click the link to "Face of Thicken 2". I have colored the relevant face differently than the rest of the part so that it stands out.
I spent a lot of time figuring out how to get the sketch & loft tools (boundary surface for the most part wasn't capable enough) to model this smooth surface (it wasn't easy, repeatedly had to backtrack!). Then I mirrored it and applied some changes that were specific to each side. Finally, I used "Thicken", although due to curvature and/or corners some of the surfaces could not thicken and I had to manually enclose things using boundary surfaces.
It was only later, after running interference detection with another part, that I realized one half of the thickened loft is different than the other half. Specifically, one of the inner surfaces created by the loft has unexpectedly strange curvature. This is surprising, given that the loft was mirrored.
Here is a view of the problematic surface:
And here is a section plane from the perspective of the "back" plane, showing that the inner surface of the "thicken" on the left side has an unexpected shape that doesn't match the original surface, and is different from the shape of the right side:
Hoping someone might have an idea about it, thanks for looking!
I spent a lot of time figuring out how to get the sketch & loft tools (boundary surface for the most part wasn't capable enough) to model this smooth surface (it wasn't easy, repeatedly had to backtrack!). Then I mirrored it and applied some changes that were specific to each side. Finally, I used "Thicken", although due to curvature and/or corners some of the surfaces could not thicken and I had to manually enclose things using boundary surfaces.
It was only later, after running interference detection with another part, that I realized one half of the thickened loft is different than the other half. Specifically, one of the inner surfaces created by the loft has unexpectedly strange curvature. This is surprising, given that the loft was mirrored.
Here is a view of the problematic surface:
And here is a section plane from the perspective of the "back" plane, showing that the inner surface of the "thicken" on the left side has an unexpected shape that doesn't match the original surface, and is different from the shape of the right side:
Hoping someone might have an idea about it, thanks for looking!
0
Best Answer
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rehevkor5
Member Posts: 13 ✭
Thanks for looking!
Yes, I couldn't get the shape I wanted there, while achieving curvature continuity, so I gave up trying to achieve that.
Taking another look, I believe the bigger problem is that the minimum curvature radius is smaller than my thicken distance... I will need to make the curve bigger/longer if I want to fix that situation. Though I'm still not sure why the mirror turns out asymmetric.0
Answers
I think your problem ist primarily caused by the poor quality of the surface you try to thicken to.
Try to analyse your Surface and create smooth transitions.
Yes, I couldn't get the shape I wanted there, while achieving curvature continuity, so I gave up trying to achieve that.
Taking another look, I believe the bigger problem is that the minimum curvature radius is smaller than my thicken distance... I will need to make the curve bigger/longer if I want to fix that situation. Though I'm still not sure why the mirror turns out asymmetric.