Union fails

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Invictus
Posts: 4
Joined: Thu Feb 14, 2019 5:12 am

Union fails

Post by Invictus »

Hi,

I'm trying to create a transition from a rectangle to a circle. I lofted 4 solids from each corner of the rectangle to the circle, and began to make unions of the solids, but the last solid could not be added to the union. Instead, it appears to give me the difference of the solids. What am I doing wrong? Could someone please help? Thanks.
Before union
Before union
Solids.png (73.13 KiB) Viewed 799 times
After union
After union
Union.png (17.06 KiB) Viewed 799 times

OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13522 (Git)
Build type: Release
Branch: releases/FreeCAD-0-17
Hash: 3bb5ff4e70c0c526f2d9dd69b1004155b2f527f2
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/UnitedKingdom (en_GB)
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Flue5.FCStd
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microelly2
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Re: Union fails

Post by microelly2 »

Sometimes it helps to move one object a little bit (micrometer).
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easyw-fc
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Re: Union fails

Post by easyw-fc »

I made a boolean fragment and then created a solid from external faces
solid.PNG
solid.PNG (215.36 KiB) Viewed 788 times
Flue5-solid.FCStd
(163.14 KiB) Downloaded 27 times
Invictus
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Re: Union fails

Post by Invictus »

Thanks, easyw-fc it worked!
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NormandC
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Re: Union fails

Post by NormandC »

easyw-fc wrote: Thu Feb 14, 2019 8:39 am I made a boolean fragment and then created a solid from external faces
Unfortunately, the end shape is no longer parametric.

Invictus wrote: Thu Feb 14, 2019 5:26 am I lofted 4 solids from each corner of the rectangle to the circle
There's a much more efficient method: create only one Loft, and use Part Mirror to mirror it on two planes.

Invictus wrote: Thu Feb 14, 2019 5:26 am Instead, it appears to give me the difference of the solids. What am I doing wrong?
It's not the difference between the solids, the operation fails and produces only some of the faces. The problem is that the OCC kernel struggles to handle tangency between solids in Boolean operations. The lofts all end up with the same circular section at the top, causing tangency. The trick is to remove the tangency condition, which is easy here: make a single loft, and cut it along the XZ and YZ planes to keep only a 1/4 of it.

Boolean operations sometimes have trouble with solids that have co-planar faces, but they don't struggle as much as with tangency.

FC_Invictus_Flue5_01.png
FC_Invictus_Flue5_01.png (9.09 KiB) Viewed 717 times

Then mirror it, fuse it with the loft; mirror the fusion, and fuse again.

FC_Invictus_Flue5_02.png
FC_Invictus_Flue5_02.png (24.08 KiB) Viewed 717 times

Finally, set the Fusion001's Refine property to true to get rid of the residual edges on the top planar face.

FC_Invictus_Flue5_03.png
FC_Invictus_Flue5_03.png (22.6 KiB) Viewed 717 times

This results in a fully parametric model.
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meme2704
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Re: Union fails

Post by meme2704 »

My solution
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couronne du roi des fous.PNG
couronne du roi des fous.PNG (42.13 KiB) Viewed 706 times
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meme2704
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Re: Union fails

Post by meme2704 »

Even more crazy, model with bells with ball inside :lol:
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couronne du roi des fous1.FCStd
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couronne du roi des fous1.PNG (116.2 KiB) Viewed 688 times
freecad-heini-1
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Re: Union fails

Post by freecad-heini-1 »

meme2704 wrote: Sat Feb 16, 2019 10:41 am Even more crazy, model with bells with ball inside :lol:
Hellau (Mainz) and Alaf (Colone). Karneval.
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