All blades have the same size, 36cm long, aerodynamically well shaped. But. The first weighs 120g, the second 125g… And the third one 210g… This is a small problem. So what are my options now? Making a new blade would be the last option, but do I have any other options?
I have no experience here but could you add weight to the others to make them heavier? Maybe tape strips that will have minimal aerodynamic impact? If not, maybe sand or shave down the heavier ones until they match?
I don't believe that the reason for this is density changes of the wood but more likely imprecise dimensions.
I can't really tell from the picture, but the lower blade seems slightly larger or maybe even thicker.
For example, the section marked in green at the heavy blade seems to be bigger than the blue marked section of the light blade. So I would suggest sand paper.
Could be. I'll try a mix of grinding and hollowing probably.
Drill a hole in the heaviest one then use putty to cover the hole back up. For the one that's just slightly heavier you could probably remove enough with sandpaper to even them out.
Sounds relativly easy and functionable, I'll try it in this way probably.
Uneven spacing to compensate for the weight difference?
Could recess on the underside of the lighter fins near the center of mass and add some weights to balance. I'm picturing those rim-weights they use for car tire balancing. Organic materials usually have these weird density variations.
You could rebuild with a more density-consistent wood, I'm picturing really light like balsa or really dense like red oak or something. Assuming these are from stock 2x lumber you should check the butt ends and try to match the ring thickness and minimize the knots in your lumber pick.
Idk about sanding/removing off 80g worth of material without affecting aerodynamics.
Can I ask your process for making these?
First: Thanks dir the information and ideas, maybe I'll try it in this way (still collecting ideas). Second: It's my first wheel, I cut the rough shapes out of a board and shaped it by filing, cutting and sanding.
Happy to help, although I have no clue what you're building.
Is this for a wind turbine?
Take some sand paper and grind a little off of the heavier ones? (No idea if that would ruin your aerodynamics too much)
Yes, I'll try a mix of grinding and hollowing probably.
Make the heaviest hollow?
Yeah, or cut a hole in the blade and fill it up with something lighter. I'll try it in this way probably.
Can you drill from the faces closest to the center of rotation on the heavy ones?