Those use machines, but I read some just sanded them from a block.
I have viewed this video. It gives a nice explanation of the manufacturing process of 2-bladed airplane propellors. The manufacturing process is about the same as the manufacturing process of wooden shoes. So it is a traditional process of copying. This requires a big number of originals with different diameters and pitches. The same procedure has also been used for making windturbine propellors of Windcharger.
With modern milling machines, a totally different manufacturing process is possible for which the geometry is defined in a computer program and for which the final shape of the blade is made on a milling machine with several grades of freedom of the movement of the cutter. This results in a much more accurate geometry and a much smaller removal of material by sanding.
Back to the original question. Why you want to make a 3-bladed rotor completely out of wood? If I look at the total thickness of all sheets together, you use a lot of wood. If you make three separate wooden blades and connect the blades by a steel hub assembly with twisted spokes, the amount of wood you need is much less especially if you make blades with a constant chord and a constant blade angle. Those blades can be manufactured very fast in large quantities if you have rotating cutter with the shape of the back side of the airfoil in it. Wind tunnel test have shown that those rotors can have maximum Cp values of more than 0.4. The only thing you have to be alert for, is to prevent that the blade is too slender because this makes the blade sensible to flutter and you also can get a too high bending stress at the blade root. But you get acceptable blades for a 3-bladed rotor if the design tip speed ratio isn't chosen higher than 6.5 (see report KD 484). So why all this effort to glue the blades together at the centre? I think that the way you have done it is okay and that the stress in the glue is sufficiently low if you use epoxy glue of good quality.
