Just as a point of possible interest, an old Materials Engineering book gives this information about Sugar Maple and Black Walnut with 12 percent moisture:
Density: Walnut = .55, Maple = .63 (heavier)
Bending (Modules of rupture): Walnut = 14600 PSI, Maple = 15800 PSI (stronger)
Max Crush Str (par to grain): Walnut = 7600 PSI, Maple = 7800 PSI
Hardness (load required to imbed a .444 dia ball to 1/2 it's diameter) Walnut (end) = 1370 Lb, (side) = 1050 Lb, Maple (end) = 2330 Lb, (side) =1840 Lb.
Max Shear Strength (parallel with grain): Walnut = 1010 PSI, Maple = 1450 PSI.
This data basically says that Maple is heavier, harder and stronger than Walnut.
As one who has worked with both, I would have to agree.
zonie