Intersection of 2 protrusions [SOLVED]

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chesss
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Joined: Thu May 28, 2020 3:48 pm

Intersection of 2 protrusions [SOLVED]

Post by chesss »

Hello,

I'm using FreeCAD 0.18 on Linux.

I made a sketch in the plan XY and protrusion in the direction Z
I made a sketch in the plan XZ and protrusion in the direction Y (see the screen capture)

The 2 sketches are working fine (no error).
The 2 protrusions are fine too.

When I make a boolean intersection of these two parts,
there is no error,
but the result called "common" is empty.

Please is it a known bug or I am I doing something wrong ?
Attachments
FreeCADcommon.png
FreeCADcommon.png (146.38 KiB) Viewed 1885 times
Last edited by chesss on Thu May 28, 2020 7:08 pm, edited 2 times in total.
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microelly2
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Re: Intersection of 2 protrusions that should not be empty

Post by microelly2 »

Welcome to the forum.
Can you upload the file?
Sometimes there are errors if the parts have faces in the same plane.
Maybe this is the reason.
openBrain
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Re: Intersection of 2 protrusions that should not be empty

Post by openBrain »

Hi, Welcome

As @microelly2 said, I think there are coplanar faces between the 2 solids. This is known to lead to errors in boolean operations.
chesss
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Re: Intersection of 2 protrusions that should not be empty

Post by chesss »

Thank you very much for your help.
I didn't find any coplanar faces.
I uploaded the file.
Attachments
FrontBase0.FCStd
Protrusion intersection error
(20.72 KiB) Downloaded 67 times
openBrain
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Re: Intersection of 2 protrusions that should not be empty

Post by openBrain »

Just forcing a full recompute makes it OK here (right-click model name 'FrontBase0' in the TreeView, click 'Mark to recompute', press 'F5'). ;)
chesss
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Re: Intersection of 2 protrusions that should not be empty

Post by chesss »

In case of the boolean "cut" would work better than the "intersection", i reversed the sketch and cut.
It's better but one zone that shoud have been cut is still here.

Recompute doesn't work here (neither with intersection or cut).

It looks like a Bug.
Attachments
FreeCADcommon2cut.png
FreeCADcommon2cut.png (156.7 KiB) Viewed 1844 times
FrontBase1cut.FCStd
(74.35 KiB) Downloaded 68 times
Last edited by chesss on Thu May 28, 2020 5:54 pm, edited 1 time in total.
openBrain
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Re: Intersection of 2 protrusions that should not be empty

Post by openBrain »

It's visible why on your screenshot. A cut line is perfectly aligned with a seam line. This sometimes can lead to problems similarly to coplanar faces.
drmacro
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Re: Intersection of 2 protrusions that should not be empty

Post by drmacro »

Coplaner issue. :(

I moved SketchXZ .1mm and all is good:
FrontBase_mac.png
FrontBase_mac.png (80.33 KiB) Viewed 1844 times
Attachments
FrontBase1cut_mac.FCStd
(58.76 KiB) Downloaded 62 times
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
chesss
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Re: Intersection of 2 protrusions that should not be empty

Post by chesss »

OK, I new for coplanar faces, but I never had any problem with lines.

Thank you very much it works now.
drmacro
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Re: Intersection of 2 protrusions that should not be empty

Post by drmacro »

chesss wrote: Thu May 28, 2020 7:05 pm OK, I new for coplanar faces, but I never had any problem with lines.

Thank you very much it works now.
Well, basically any sketch that creates or geometry that ends up coplaner can cause the issue.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
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