.Map :: MoHAA Mapping

Sometimes when i subtract brushes, suddenly huge new brushes appear. Then i delete them, but my question is how can i prefent this?

Don't use CSG subtract. Simply use the clipper (x) instead

ok

That probably happens because one or more faces are not on a grid line. Brush faces can get off the grid when you resize or rotate brushes. The csg cutter does not handle 1/2 unit cuts very well. Try using "Snap Points to Grid" under Selection, if you can. And, you should alway do your cutting on a new map and make a prefab out of the result--to prevent crashes.