914Pete, the bushing is cooper or brass from a hobby shop with a 1/4" inside diameter or you can make them out of delrin(3/8ths outside diameter x 1/4 inside diameter}. The deminsions for 4 of the aileron blocks is on page 49 of my plans and the one on each end of the wing is on page 50. This block is to fit the width of the last two ribs x 1 inch wide. The other blocks are tapered from 1 inch x 2 1/2 inch where they glue on the aileron rib down too 5/8ths x 1 inch. I hope I am explaning this corectly! Good luck. Scott in Iowa has drawings of these blocks and the delrin bushings.
On page 52 of my XL plans there is a better drawing. As far as bushings, I found some bronze bushings at Home Depot. They are 1/4" ID 3/8" OD and about 1" long. I'm putting two bushings in each block with the excess cut off.