Offset Surfaces with join Cone problem

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satefan
Posts: 13
Joined: Tue Nov 27, 2018 9:34 pm

Offset Surfaces with join Cone problem

Post by satefan »

OS: macOS 10.16
Word size of FreeCAD: 64-bit
Version: 0.20.29177 (Git)
Build type: Release
Branch: (HEAD detached at 0.20)
Hash: 68e337670e227889217652ddac593c93b5e8dc94
Python 3.9.13, Qt 5.12.9, Coin 4.0.0, Vtk 9.1.0, OCC 7.5.3
Locale: C/Default (C)
Installed mods:
* CurvedShapes 1.0.4
* Curves 0.5.4


Hello,

I am trying to create a cilinder shape (a loudspeaker) based on specific surfaces (created with the Surface Workbench based on a set of wires. I managed to create the surfaces needed and used 3D offset to apply thickness. When i join the 3 offsets, I get my basic shape for my loudspeaker.

As soon as I apply a boolean operation, joining the cilinder (Fusion011) with the Cone, i get very unexpected results. I attached the project.

Here is what I see before the boolean operation:
Screenshot 2022-11-24 at 18.57.42.png
Screenshot 2022-11-24 at 18.57.42.png (334.46 KiB) Viewed 621 times
Here is what i see after boolean operation:
Screenshot 2022-11-24 at 18.58.40.png
Screenshot 2022-11-24 at 18.58.40.png (332.07 KiB) Viewed 621 times
I have tried various strategies/orders, but I suspect there is a more fundamental problem.

Hope anyone can lend a hand here. Help is much appreciated.

Satefan
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Vincent B
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Re: Offset Surfaces with join Cone problem

Post by Vincent B »

This is a solution made with offset3D...but could be made with part design otherwise :roll:
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Capture.JPG
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Shalmeneser
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Re: Offset Surfaces with join Cone problem

Post by Shalmeneser »

Vincent B wrote: Thu Nov 24, 2022 8:51 pm This is a solution made with offset3D...but could be made with part design otherwise :roll:
Challenge accepted
Attachments
Capture du 2022-11-24 23-22-56.png
Capture du 2022-11-24 23-22-56.png (40.22 KiB) Viewed 542 times
Halo_Experiments6_SHALM.FCStd
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chrisb
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Re: Offset Surfaces with join Cone problem

Post by chrisb »

I would too recommend to start with a revolution, be it iin PartDesign or in Part workbench.

In case you are interested why the OP model fails: It is a so called coplanar issue. If you turn the Fusion and move the cone a bit, the union succeeds. This would of course require a different sequence of operations.
SnipScreenshot-297737.png
SnipScreenshot-297737.png (50.23 KiB) Viewed 514 times
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(925.12 KiB) Downloaded 11 times
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satefan
Posts: 13
Joined: Tue Nov 27, 2018 9:34 pm

Re: Offset Surfaces with join Cone problem

Post by satefan »

Thanks all for your help and insights.

The surfaces in the example I posted ensure the driver (tweeter) fits nicely in the hole and the surface of the cilinder will be a continuum. If i use a normal cilinder and put a hole in it, the tweeter (with a flat faceplate) will not fit nicely. That is why I did not go for the revolve option.

I will research the option for the coplanar issue. The cone has to be exactly at the back of the cilinder below the rear facing tweeter.

May come back here with a question or 2.

Thanks again!

Satefan
satefan
Posts: 13
Joined: Tue Nov 27, 2018 9:34 pm

Re: Offset Surfaces with join Cone problem

Post by satefan »

Reporting back here with good progress.

I recreated the cylinder, but got similar results. Either the cone was still misformed or Freecad crashed on my appearantly demanding compute requests. Especially doing Fillet made Freecad very unhappy.

During the hours of fiddling, i noticed (thanks to the input here) that the result of the join with the cone was dependant on the position and rotation of the cone. Long story short, i created the cylinder object and separate cylinders for the top and bottom, so i could apply a Fillet to them. When joining the main cylinder, the bottom and top and the cone, and rotating each with a specific degree around their own Z axis, I was able to avoid the co-planar issue and the join succeeded!
Screenshot 2022-11-26 at 19.21.54.png
Screenshot 2022-11-26 at 19.21.54.png (358.34 KiB) Viewed 349 times
Still lots to do to get to the end result, but I think there is light at the end of the (cylindrical) tunnel!

Thanks for your help and support!

Satefan
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