I recently had my first experience with Hinge Point hinges. The biggest problem I had was alignment from one control surface to the other. I followed Robart's directions, but still had some stiffness due to misalignment. I discovered my own technique. I mark and drill one control surface first and then insert the hinges (not glued as yet). I draw a horizontal center line on the other surface and then use the hinges themselves, while in the first control surface, to mark the exact location of the mating hole. This worked much better than marking and drilling all holes at the same time.

Paul