When you apply smoothing you should select the first box. I think it says smooth groups or something like that. Leave the second one alone, since that causes some weird shadow affects on the objects.Udo.:-waveP.S.Select the box with " Auto Smooth ".You can see with my plane that around the windowsis smooth.

These sorts of problems can be seen in many 3d modellers, it's a generic boolean thing I must conclude.A couple of tips which often (not every time, and no promises this time!) work are these:When you have two objects which are to be the subject of a boolean operation of any kind, it's good if the faces, where the objects intersect, and therefore where they will act on each other, are triangles, and the more of them in that immediate area, the better the results will often be.It's also good if the two objects are completely enclosed spaces. Even if that means adding some temporary closing polys where there are apertures. Some boolean coding repsonds very well to that method.I've no idea why this works exactly in any detail, but it has saved my hide a few times down the years I am happy to report. I've had times when those two tricks could not help, but mostly they did!Hoping it'll work it's magic this time for you.

These sorts of problems can be seen in many 3d modellers, it's a generic boolean thing I must conclude.A couple of tips which often (not every time, and no promises this time!) work are these:When you have two objects which are to be the subject of a boolean operation of any kind, it's good if the faces, where the objects intersect, and therefore where they will act on each other, are triangles, and the more of them in that immediate area, the better the results will often be.It's also good if the two objects are completely enclosed spaces. Even if that means adding some temporary closing polys where there are apertures. Some boolean coding repsonds very well to that method.I've no idea why this works exactly in any detail, but it has saved my hide a few times down the years I am happy to report. I've had times when those two tricks could not help, but mostly they did!Hoping it'll work it's magic this time for you.(Sorry if this does show as second post, the first attempt seemed to just vanish without trace.)