ORIGINAL: Ttaylor63
Plane is an edge 540 1/4 scale. The manufactuer calls for 15 degrees on elevator, 25 for rudder. I just don't know how to convert.
I have drawn three gauges for the angles you need.
If you want, you could copy them in balsa or cardboard.
Note that the vortex of the angle must be in line with the hinge line.
For 15 degrees: 13/16" x 3"
For 20 degrees: 1-3/32" x 3"
For 25 degrees: 1-13/32" x 3"