First of all make the slot for the hinge at an angle down, so it doesn't touch the top of the surface. meaning the hinge when inserted makes an angle downward. I make a groove in the leading edge of the surface and in the trailing edge of the stab (for the hinges center) so there is no gap at all between them, and I also use some covering to seal it. make sure the hinges center doesn't stick out of the top of the surface