Boolean Subtraction

[chach]

You'll have to make sure that your source object's surface is closed, and, after you finish the boolean, collapse to editable mesh and go to sub obj > face > select all > unify normals to see what surface goemetry is really there. a faster way to do this test would be to apply a double-sided material so you can tell what faces exist no matter which way they're facing.

[Croglet]

No joy.
The object had a load of modifiers on it but I don't see how that should matter if its been collapsed.

[chach]

has it been collapsed, or, does it have a load of modifiers on it? when i say that the surface should be closed I mean that it should not have any holes or inverted normals on it; not just collapsed...but it should be collapsed too.
So, collapse it, delete stray vertices, unify normals, inspect the entire surface visually; then, collapse the other operand before the boolean too. Also, you'll want to manually align as many intersecting vertices as possible before the boolean. bottom line, you want o do everything possible to simplify both of the operands and their intersections before you apply the boolean.

[Croglet]

i see what you mean. The object has no modifiers but it is actually a rim with spokes so i guess it does have holes and it was quite an untidy mesh to begin with.
Back to the drawing board!

Thanks for the help though!

[chach]

the spokes can be OK, because the volume of the object is contained, but not if the mesh is too chaotic. something i've had luck with, when making & booleaning complex objects, applied to a spoked wheel is: create your base 'rim' object so that its faces define not only the perimeter & curvature of the rim, but so the faces accomodate the addition of the spokes as well. for instance, you might select every other vertice on the interior or the rim and rotate them together so that they rest on the edges that the spokes will be inserted into. Then, when you create your spokes, create them with an array (as cylinders - keeping the volumes closed,right?) , attach them to one-another so they're one object, then boolean them in all at once. this type of boolean optimization will increase the success rate of the boolean operation.
hope it helps.

[3rd Dimentia]

I avoid booleans like the plague. THEY'RE EVIL! EVIL I TELLS YA!. If I need to do anything like that, I generally use a shapemerge to cut holes and then build the geometry up from there. You have a lot more control that way.

[FatAssasin]

Booleans in general are pretty messy to deal with, and there has to be some preplanning involved to make sure your meshes are closed, like chach said.

But they are necessary some times. And the best way I've found to clean up the mesh afterwards is to convert the mesh to an editable poly and use the Vert Weld dialogue box to quickly get rid of most of the extra verts, and then use the Remove button on any extra edges and verts you don't want.

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