Need help how to use tool to find a plane

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luggw1
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Need help how to use tool to find a plane

Post by luggw1 »

Code: Select all

OS: KDE Flatpak runtime (XFCE/xfce)
Word size of FreeCAD: 64-bit
Version: 0.20.1.29410 (Git)
Build type: Release
Branch: (HEAD detached at 0.20.1)
Hash: f5d13554ecc7a456fb6e970568ae5c74ba727563
Python 3.9.9, Qt 5.15.5, Coin 4.0.0, Vtk 8.2.0, OCC 7.6.2
Locale: English/United States (en_US)
Installed mods: 
  * Help 1.0.3
  * Assembly4 0.12.4
As I've stated in the past, I'm working on a model in HO scale (1/87) of a roundhouse for my model railroad. I've come to a point in the model where I need to model the roof of a section called the "Lean To" that has an odd shape and I could use some suggestions as to how to go about it. Here's a snapshot of the area I'm talking about.
LeanTo.png
LeanTo.png (88.79 KiB) Viewed 750 times
It's may be obvious, but this snapshot is of an assembly put together in the Assembly4 workbench. The parts were all modeled in separate files.

The red arrows show the vertical columns on the back wall the bottom plane of the roof should rest upon, the green arrow shows a point in the corner 200" above the floor at the peak of the roof and the orange line approximately traces the line at which I believe the plane would intersect the four back walls of the stalls and the side wall of the fifth stall.

My question is what tools in FreeCAD would be best suited to establishing this plane, perhaps as a datum plane(?) and then building a roof structure off of it? The structure needn't be much more that a hollow wedge, but the shape needs to be correct to fit into the nooks at the walls and to get the slope correct.

Any help will be greatly appreciated.
Bill Lugg
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papyblaise
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Re: Need help how to use tool to find a plane

Post by papyblaise »

make a rectangle at the profile of the roof along each panel of the round wall, another above the straight walls, then a loft
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luggw1
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Re: Need help how to use tool to find a plane

Post by luggw1 »

papyblaise wrote: Mon Jan 30, 2023 5:31 pm make a rectangle at the profile of the roof along each panel of the round wall, another above the straight walls, then a loft
I've given some thought to your suggestion and, with all due respect, I don't think it's going to work.

You see the only knowns are the straight walls (refer to the red arrows), the short wall with the sloped top and the point in the corner I mentioned 200" from the floor (green arrow). The orange line is my approximation, but not a known. The goal is to establish a plane that rests on the straight wall and the short sloped top wall and (hopefully) passes through the 200" high point at the corner. Then I would be able to find its intersection with the sidewall (facing the viewer) the the backs of the four stalls. My question is how to establish that plane and turn the intersection into something I can use to model the roof.

Hopefully, that clarifies the situation a bit.

Bill Lugg
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onekk
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Re: Need help how to use tool to find a plane

Post by onekk »

Hello.

The point is that you are using an assembly tool and you have to find where things go relatively one to another in 3d space.

you don't have a unique solid on which as example you could make a slice and then use this data as you want so it is not properly a CAD task.

One "quick" and dirty way is to:

- Set view from top.
- Take and note down some 3d coordinate.
- Make a wire from them
- Make eventually a face.
- Check if everything is correct.

based on points you could place other solids as you have coordinates.

But I could be wrong and someone could have better ideas, or have a better workflow.

Regards
Carlo D
GitHub page: https://github.com/onekk/freecad-doc.
- In deep articles on FreeCAD.
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papyblaise
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Re: Need help how to use tool to find a plane

Post by papyblaise »

the profile of the roof along the high facade, a sweep of this profile with the edge of the low wall, a Boolean subtraction with the rotunda
Attachments
arena.FCStd
(37 KiB) Downloaded 11 times
arena.JPG
arena.JPG (43.77 KiB) Viewed 479 times
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luggw1
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Re: Need help how to use tool to find a plane

Post by luggw1 »

Well, after some consideration of the suggestions offered, the attached file (LeanToRoof.FCStd) is what I came up with as a solution to the problem. Thanks for the assistance.

Now I'm having one additional problem I can't figure out. I've made a simple copy of the roof and am endeavoring to cut it into printable chunks. I also want to hollow the chunks using the thickness tool in the Part Workbench. I attempted to do that in the attached file without success. It doesn't seem to add the thickness I desire, but it adds a strange spurious solid bit. If I check the Intersection checkbox, it adds the thickness I want, but to the outside, making the part too big.

Am I expecting the tool to do something it can't do, or is there a setting I'm missing?

Thanks
Bill Lugg
Attachments
RHMaster.FCStd
(24.23 KiB) Downloaded 8 times
LeanToRoof.FCStd
(226.2 KiB) Downloaded 8 times
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