HelloI get strange lines when i do boolean subtraction for more then two objects, i itried to unit objects and subtract i still get those strange lines.....

What strange lines are you referring to?Could they be the original 2D geometry used to create the 3D model?

i draw 3 boxs 1 subtracted when i click boolean the diagonal line appears, is that normal?? thanks :) 

i solved it by using proboolean