||09-17-2011 07:34 AM
Not sure I exactly understand what you mean, but having dealt with a couple of range hoods-
Most range hoods are flat on the top side, and are made to mount to a a flush flat surface. Above the stove, I suspect that there is a lip of cabinet edge across the front and two sides. This lip does not allow the range hood to sit flush against the bottom of the cabinets. Is this the "edge" you are describing? If so, you need to add some filler strips to the underside of the cabinet. Measure the depth of the recessed area, cut some wood scraps to the same thickness, and screw them in from the inside of the cabinet. That will present you with a flat surface, to which you can fasten the range hood.
If this is not your situation you may want to post some pictures.