Jeff, I conclude from your posts that you may not be planing to set the Robart hinges deep enough into the surfaces. When using them, (Remembering to coat the hinge pin areas with Vaseline) push the hinge deeper into the wood so that the two surfaces have no more gap than a CA hinge. - In the case of a tapered control surface and a square cut trailing edge, it means that the leading edge point of the surface touches the trailing edge by sinking the Robart hinge into both pieces, leaving only the hinge pin exposed.

Apply a strip of sealing material with an accordion fold to allow for the movement of the surface(s). - Heck, I use a 1" wide Ultracote or Monokote strip pre-folded lengthwise and applied in the gap from the bottom so it doesn't show from the top. This will give you good control authority at low speeds and along with a tight linkage and strong servos can push surface flutter out of your flight envelope.

quint