Additive Sweep with Subtractive cylinders

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Aurawin
Posts: 10
Joined: Mon Oct 21, 2019 3:55 pm

Additive Sweep with Subtractive cylinders

Post by Aurawin » Mon Nov 18, 2019 4:13 pm

There is a problem with the subtractive nature of cylinders when the cylinder's center is at the start of a sweep.
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Screenshot from 2019-11-18 09-49-29.png (47.52 KiB) Viewed 306 times
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Screenshot from 2019-11-18 09-55-16.png (13.09 KiB) Viewed 306 times
Screenshot from 2019-11-18 09-57-15.png
Screenshot from 2019-11-18 09-57-15.png (23.84 KiB) Viewed 306 times
If I move the last cylinder's z off the plane - even by 1nm the render if perfect. When the item is moved from the y-axis it needs to be positioned to where the entire item is no longer intersecting with the start of the sweep - which I find strange.

Offsetting the position of the subtractive does workaround the issue but it should not require me to introduce fake tolerances to get the part to render properly.
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openBrain
Posts: 3049
Joined: Fri Nov 09, 2018 5:38 pm

Re: Additive Sweep with Subtractive cylinders

Post by openBrain » Mon Nov 18, 2019 5:41 pm

Yep. seamlines create some problems. Yours is one of them. :)
There isn't much doable at FreeCAD code level because this is induced by the third party geometric kernel (openCascade). ATM, using workarounds such as slight moves is required.
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