>>212607959>why are the blade and the bow not of the same thickness?I just fucking explained to you, retard. You need the bow to be stiff, so it can tension the blade. You can't make a stiff part as narrow as the blade out of any non-exotic material, due to how area moments of inertia work. You need to place material as far as possible from the deflection axis to get stiffness, ergo you use a hollow tube for the bow.
The blade itself whips around like a wet noodle. It's not stiff at all in the plane normal axis.
The design of the metal saw is simple and elegant, but it necessitates a wider bow. You want a narrow blade, but it cannot be stiff because it's narrow. So you wrap a much stiffer, wider bow around the blade and tension it.