Need another way to set diehedral.

IF:
I level my inner and outer wings.
measurer 56 5/16" from the attach point/pivot out the bottom of the outer wing.
Raise the outer wing 4" at that point.

Will my wing have 4 degrees dihedral?

arcsin 4/56.3 = 4 deg. so you will have 4 deg per wing, or 8 deg total. This is of the outer wings. Not knowing what you're building and the length of inner and outer wings, I don't know what the average diehedral would be.

Another way to do this, so you aren't hunting around at that 56 inch point wondering what exactly 4" of lift looks like, is to cut a board at the 4 degree angle - maybe make it half of the 56.3" measurement and 2" high on the short side. Put that angled board on the wing panel to be lifted. Put a high-precision level on top of that. Then just shim up the outer wing panel until the level shows - level.

Another way to measure 4 degrees is to use the sine of 4 deg. which is .06975" and multiply that by the length of a long level, say 48" and that comes out to 3.348 or really close to 3 and 11/32. Make a shim to go under the end of the level and it will measure 4 degrees all day. I generally measure dihedral with the wings leveled to zero degrees of incidence. On my biplane (which has 2 deg. dihedral and 1.5 deg. of incidence) that means the fuselage is propped up to 1.5 deg. tail high. This really matters a lot with a swept wing.

Got no idea what you are building but with any design measurement accuracy suffers if you don't start with a zero deg X Y base line.

A degree board as Mr. Witherspoon describes works well too. You just have to know how to get the 4 degrees and know all other plains are at zero.

Back to your original question, 56 5/16" or 56.3125" x .06975=3.9147 or about .085"(less than 3/32") short of 4". Probably close enough as long as the rise measurment is taken from the same plain as the attach point.

get one of these
http://www.amazon.com/Magnetic-Angle.../dp/B0035MIQ6U

Thank for the tips. I had not found my digital level and I remembered the 56 5/16" = one degree for every one inch rise. Plus, I just wanted another way to double check my digital levels accuracy. I'll try them all before I drill my attach plates.

Thanks,
Bob