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enter image description here

I want to cut the hole with the boolean modifier but it's not working. Anyone have any ideas why?

Also, how can I trim a part from the model.


Here is my blend file:

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  • $\begingroup$ your "cube" base object has mesh problems... booleand cannot work. It seems it was created applying a mirror modifier, but in a wron way, some face is overlapping... $\endgroup$ – m.ardito Oct 19 '16 at 15:50
  • $\begingroup$ so how to solve the problem? any other addon work to cut $\endgroup$ – atek Oct 19 '16 at 15:52
  • $\begingroup$ Hi! It looks like you're asking two questions here. Could I get you to choose which of your questions you want asked on this post? One question per post is generally preferred. It just makes answering the question easier, because there isn't any confusion about what is being asked. It's also better for the indexing of the site. Feel free to post whatever question you remove from here as a separate question so that you can get an answer to that also. $\endgroup$ – TARDIS Maker Nov 18 '16 at 20:09
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It's a common problem with Boolean operation in blender; it won't work if there's incomplete or bad geometry. The problem is, the boolean is a prime culprit for CREATING the bad geometry.

Ensure your meshes have no loose geometry, remove doubles and dissolve messy faces/unnecessary vertices. Really inspect both objects before using Booleans.

By turning on surface normal lines you can spot weird geometry a little easier, if the line isn't quite centred, something is probably wrong.

I've heard that combining the Boolean modify with a solidify modifier creates better geometry.

I've highlighted the areas of concern - there's probably more. Lots of unnecessary vertices. Two faces ontop of each other (pairs of blue lines) Face normal pointing out across the surface from the vertices. enter image description here

And inside the oval, you've got some faces that don't have normals, so they're a bit bonkers.. See second picture.

Everything should be neat shapes, quads or triangles preferably.

I feel for you, it's not nice when it happens.

enter image description here

Apart from manually dissolving bad faces, snapping unwanted vertices to existing vertices and then 'removing doubles', this post explains some of the problems with non-manifold geometry.

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  • $\begingroup$ i have added both the object solidify modifier and with the geometry of the top cylinder is just we import a new cylinder . If u go through my file u will better know whats the problem $\endgroup$ – atek Oct 19 '16 at 17:08
  • $\begingroup$ I just loaded it now, instantly, looking at the chair in Edit mode, I can see really bad geometry - lots of little black dots and polygons overlapping ontop of each other where I don't think they should be. You have some cleaning up to do. I've used this in the past, but can spot these problems by eye now. wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Modeling/… $\endgroup$ – GilesDMiddleton Oct 19 '16 at 17:15
  • $\begingroup$ @atek I've updated the answer with some images of what challenge faces you (pun intended). $\endgroup$ – GilesDMiddleton Oct 19 '16 at 17:26
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I was able to fix it but it wasn't simple.

Started by removing the non-manifold face (in the middle) and manually recreating the center so that there we no interior faces.

I also used the knife tool on the one end to clean up the messed up 'mirror'. this allowed me to recreate the end shape as I believe it was desired.

Now to get to your real question, the below image is what would have happened if you were able to do the boolean modifier as presented. A 'ring' would have been cut out where your cylinder was.enter image description here

I do not believe that this is what you intended and instead you meant to end up w/ something like the following: enter image description here

To create this whole, your cylinder needs to NOT be a 'real' cylinder (with thin walls and an empty center) but a full cylinder. When the boolean modifier is performed, you should then be able to remove the hole as desired.

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