# Boolean Modifier Trouble

I'm having trouble with the Boolean difference modifier. It isn't cutting out some pieces of the mesh:

With the difference mesh hidden (note the lack of the rectangular cutouts)

All the normals are in order:

The modifier is not showing any errors or warnings. Paste all .blend link

In addition to any potential solutions I'm also interested in the description of situations when it happens and an explanation of the cause.

## 2 Answers

You can fix this problem by first triangulating the mesh you wish to carve holes into. The large ngons on the top and the bottom make it hard for blender to create these holes.

1. Go into Edit Mode, Tab

2. Select the mesh you wish triangulate, A or hover mouse of mesh and press L

3. Triangulate the mesh, CtrlT

You will notice that the error message under the modifier is now gone.

• I did not get the error message in the first place. – Michal Nov 5 '14 at 18:28
• @Michal, that's what I get when I open your blend file. What version of blender are you using? – Vader Nov 5 '14 at 18:29
• 2.67b. I'll try upgrading to the latest version – Michal Nov 5 '14 at 18:34
• @Michal that would be a good idea. – Vader Nov 5 '14 at 18:41
• Wow, upgrading eliminated the need for the problem as 2.72 has a good DXF importer! Triangulating indeed fixed the issue – Michal Nov 5 '14 at 19:13

Blender was throwing exceptions, you just have to check the System Console by going to Info > Window > Toggle System Console. To get rid of the exceptions I just selected the rectangles and separated them into another object. Then I applied the Boolean modifier for the cylinders, then added and applied one for the rectangles. This gives me this result:

• I'm looking for a way to automate this. In general if I separate by loose parts, add a modifier for each seperated part the problem persists – Michal Nov 5 '14 at 18:33
• @Michal You have to apply the first modifier, then the second. This works for me – BlendingJake Nov 5 '14 at 18:34