Watch Shakky's video of my map at 3.50 mins, the cube goes through the grate texture, how do i stop this from happening.
http://www.youtube.com/watch?feature=player_embedded&v=hcF-YnONjTc

move the grating further away from the surface;
make the grating thicker

Those are the best two ways to make it harder. But yeah; gratings are glitchy. Try to avoid them were possible.

I think i will avoid them. I did place the portal surface further away, it did stop the cube from going through, but this caused another problem, the cube stayed in the gap, allowing the player to smuggle the cube through another portable surface.

Dont use Nodraw "under" the grate
That should work