After seeing the thread entitled 'Persistance pays off CNC Blades' by letERblow I've been inspired to make some wind turbine blades using this method. I'm using a milling machine I converted to CNC at the moment. Unfortunately it's a bit limited for doing blades since the Y axis is 140mm and X axis is only 350mm or so, hence I've had to do these 600mm blades in two parts.
Some photos...
I made an Excel spreadsheet to calculate the profile of the blades and output sets of points for each cross section along the blade by rotating/scaling a NACA 4412 airfoil. This is then imported directly into solidedge, making it extremely quick to experiment with the parameters in the spreadsheet and see the result in 3D. I then imported this 3D model into 'QuickCAM Pro' (I chose that program simply because they had it at school...) to generate the G-code to run the machine.
I'm currently using plywood, purely because that's what I've got lying around. How well will plywood blades hold up in practice? I've tried looking on this forum for this information but haven't been able to find much. As far as I can see the grain direction in plywood clearly isn't favorable, the blades I've made do have a fair bit of flex in them. I would like to make blades for my 3.2 meter diameter variable pitch wind turbine using plywood since it's cheap etc...if it is safe to do so.
