I've been lurking for a couple years and have an ECM with PVC blades limping around and around. It's just for fun, no furling, but it actually generates
some power. I've begun to realize that, at some point, I've got to make/buy some
real blades and get the RPM's up where they belong. The existing blades are 32" each for an overall diameter (with hub) of about 68". I believe this is probably too big for the speed the ECM needs.
I (sort of) get the blade carving thing for the Dan's and Hugh's blades, but I'm intrigued by the GOE222 profile.
I think I may have come up with an idea that might make carving the profile
fairly easy.
I'm sure you all will tell me if I'm right, half-right, or nuts.
Here's the idea - based on a finished 2x4 blank...
GOE222.pdf (14.58 kB - downloaded 1218 times.)
I've got way too many stations listed for a 2x4, I know, but I imagine it could be scaled up and then they might be useful. I did it in inches 'cause that's how I started. I suppose someone smarter than I could put these numbers in a spreadsheet (whatever that is) and make it automatical, but that's out of my league.
I plan on trying this on a cedar 2x4x96 and kerfing the whole length. I'm lazy, so I'll cut the kerfed blank into my finished lengths and fill the kerfs with glue or something for the area where the blades attach to the hub. One board should make balancing easier (I think), and will mean only however many passes per side rather than 3X. I'm going to start with ~32" blades because I can always make them shorter. I expect I'll end up at 24" or thereabouts.
I'll post pics of the carnage when I've finished...
,,,or given up.