My first scratch build from plans by AMA Plans Service. It is the "Old School" design and drawn by Larry Kruse. It's a design that is directed toward the new builder. The plans call for 1 1/4" dihedral at each wing tip. This is my problem How do I get the 1 1/4 inch dihedral. This may sound simple to some but to me it's driving me out of my mind. What is the best method to sand the center ribs to conform to this dihedral.

Thanks
Mikw