Boolean difference removes wrong part

I have a cube that is scaled about 10 times on the Z axis. I added a plane, rotated it 45 degrees on the Y axis, and placed it just below the top of the cube. I applied a boolean difference modifier to the cube, and it cut off the bottom. How can I invert the boolean operation to cut off the top of the cube instead? The plane should be deleted after the cutting.

• it depends on the face normals, flip the plane 180° and try again Mar 25, 2015 at 23:34
• You can flip normals on the plane to fix that. Mar 25, 2015 at 23:34
• – user1853
Apr 26, 2016 at 18:42

The Boolean modifier calculations depends on the face normals to decide what's inside and outside ; for a simple plane case the face normal is the local z_axis so it's enough to flip the plane 180°

for other case :

• enter edit mode hit Ctrl+N
• check inside option on the tools panel
• Also note that you can use Ctrl Shift N to enable the inside option without an extra step
– gandalf3
Jul 10, 2015 at 18:52

you can use a different kind of operation on the boolean modifier for different results: