I've done some stress testing on the PVC, Dan. Put in the freezer at -18C (never gets that cold in here), and start bending it again. No problems. Whe nhitting it with a hammer -and still takes effort-, pieces will shatter from it.
I couldn't break the first protype blade I made, which was only 2,3 mm. This one is 3,2mm thick I believe. It's like breaking a CD-ROM. You can't! (unless you go back/forth all the way to the end).
I'm carefull with it, though.
It was just one blow of wind this time, which was harder than the average that day, otherwise I wouldn't have put the mill outside. With load, the windmill will go a lot slower anyway.
And yes, I will use different wood now, probably unlayered stuff, although I've been thinking of some metal too, that could be bended so the blades are position on a nice angle, and I could attach it with more screws then. But I have no idea where to do that.
Sponge