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Old 11th November 2018, 06:34 AM   #1
cpot
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Default Subtract a tube from a wall

Hello,

Sorry to ask so many questions, but the trial will not last long.

I want to cut a hole in the wall or at least make segments from the intersect of the tube and the wall.

I understood that the tube and the wall must be an 'Object', selecting all surface was not enough to do boolean operations. I created then 2 objects.

Then as one is not a closed object (wall), i have been advised to use "knife" which i did.

Then i go the second screenshot, not exactly what i expected :-)

Best,
Chris
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Old 11th November 2018, 10:55 AM   #2
Andy
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Default Re: Subtract a tube from a wall

There are many requirements for booleans to work correctly. Both objects must be fully enclosed 3D shapes with no holes, and all normals facing outwards. After hearing that you had to remove so many duplicate vertices, I suspect the main shape is not perfect for this.


Try selecting Tools->select-leaky surfaces and seeing if anything is selected. It may be too much to fix so I'd suggest making the shape you want and moving that into position to replace the 'wall' where you want the hole area.
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Old 11th November 2018, 01:23 PM   #3
cpot
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Default Re: Subtract a tube from a wall

Quote:
Originally Posted by Andy View Post
There are many requirements for booleans to work correctly. Both objects must be fully enclosed 3D shapes with no holes, and all normals facing outwards. After hearing that you had to remove so many duplicate vertices, I suspect the main shape is not perfect for this.


Try selecting Tools->select-leaky surfaces and seeing if anything is selected. It may be too much to fix so I'd suggest making the shape you want and moving that into position to replace the 'wall' where you want the hole area.
you are right ... 2026 surfaces with leaky edges (which means?) ... it means that a lot of functionalities will not work ? is there a rather quick fix ?

Will all my X-plane sketchup .obj export when ac3d re-imported will be the same ?

Best,
Chris
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Old 11th November 2018, 05:04 PM   #4
Andy
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Default Re: Subtract a tube from a wall

I can't say for sure, but it's possible that the stuff coming out of Sketchup is not perfectly optimized for use elsewhere.

Leaky means that you have holes or open edges e.g. polygons that are close to each other but their vertices aren't shared. Modeling with a leaky object is fine, unless you want to use Booleans (Booleans need 'solid' objects).

If the object you have looks like it should be non-leaky i.e. no obvious holes, you might try this:

Object->Optmize-vertices
Object->Optimize-surfaces

Then try Tools->Select-leaky-surfaces. If it says you have holes, you could try Object->fill-holes.

You can quickly check for normals being oriented by selecting everything and setting it to single sided ("1S" button). If you look around and see any holes, some surfaces are facing the wrong way. Surface->Unify-normals can fix this.

It all depends what the initial model is like.

Last edited by Andy; 11th November 2018 at 05:11 PM.
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Old 12th November 2018, 04:13 PM   #5
cpot
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Default Re: Subtract a tube from a wall

Quote:
Originally Posted by Andy View Post
I can't say for sure, but it's possible that the stuff coming out of Sketchup is not perfectly optimized for use elsewhere.

Leaky means that you have holes or open edges e.g. polygons that are close to each other but their vertices aren't shared. Modeling with a leaky object is fine, unless you want to use Booleans (Booleans need 'solid' objects).

If the object you have looks like it should be non-leaky i.e. no obvious holes, you might try this:

Object->Optmize-vertices
Object->Optimize-surfaces

Then try Tools->Select-leaky-surfaces. If it says you have holes, you could try Object->fill-holes.

You can quickly check for normals being oriented by selecting everything and setting it to single sided ("1S" button). If you look around and see any holes, some surfaces are facing the wrong way. Surface->Unify-normals can fix this.

It all depends what the initial model is like.
I am currently in a business trip but i will as soon as i come back. I join attached the ac file if some interest for you

Best,
Chris
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Last edited by cpot; 12th November 2018 at 04:23 PM.
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Old 13th November 2018, 04:29 PM   #6
cpot
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Default Re: Subtract a tube from a wall

Hi,

I tried all your suggestions without success.

Therefore i tried to simplify the problem by creating a tube and 'knife' it in a single surface of the wall. i obtained the attached result (not a hole in the wall)

Did i do something wrong ?

Best
Chris
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Old 14th November 2018, 04:22 AM   #7
Andy
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Default Re: Subtract a tube from a wall

try doing the knife with a cylinder (i.e. enclosed 3d shape), not a tube.

Last edited by Andy; 14th November 2018 at 04:25 AM.
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Old 17th November 2018, 03:36 PM   #8
cpot
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Default Re: Subtract a tube from a wall

Quote:
Originally Posted by Andy View Post
try doing the knife with a cylinder (i.e. enclosed 3d shape), not a tube.
Yes i have done it with a cylinder and i have a circle in the wall but can't cut the surface...
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Old 18th November 2018, 05:04 PM   #9
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Default Re: Subtract a tube from a wall

Select the surfaces inside the circle and delete them. Or, Surface->cut-away-object if you want to put them into a new object.
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Old 5th February 2019, 09:07 PM   #10
Glenn Petersen
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Default Re: Subtract a tube from a wall

Create a tube that is longer than the wall thickness and the circular size you want. Move the tube to intersect and go thru the wall.
Select Wall first.
Then shift-select the Tube.
Goto Object menus-
Goto to Boolean
Select "Subtract"

This should make a perfect hole in the wall. It will create triangular sections on the wall allow for the cutout sections- these will still be grouped with the wall.
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