I'm doing some booleans and encountered a curiosity. If you un-hide the Box Bottom object you can see what I'm doing. The file attached has the top un-booleaned. If you look at the various objects I've made, you can see I've got a bunch of rectangles then a polyline. I originally tried to loft them all into 1 solid, but that resulted in an object that wouldn't subtract from the box top and bottom. Then I just lofted the rectangles separately from the polyline, since I'm just using them for subtraction. I was able to subtract from the box bottom with the "Wing Subtractor" object which was created by lofting, but I can't subtract from the top. I then went back to the wires and extruded the wing subtractor and it's able to subtract from the box top no problem.

What's the reason that the booleans work in one case but not the other?

Thanks!

Dan