Parametric replacement fan blades

Inspired by http://www.thingiverse.com/thing:186979 to try and fix my many broken fans, I was rather disappointed to note that those fan blades were not customizable, and were too big for the 40x40x10 fans I have.

So, I redesigned it in OpenSCAD, with a twist -- the blades are parabolic curves (I might work on trying a NACA airfoil blade profile instead), and have winglets to try to avoid a backflow of air.

I haven't tested it yet, and the dimensions I've stuffed into the file are guesstimations based on what I think the fan size is. I'll fine-tune it when I get back to the printer.

Sources are kept up to date here: https://github.com/hyperair/fan-blades

Update: winglets didn't seem to help it much -- I reduced the blade pitch and number of blades, and added a bit of linearity to the parabolic curve. It seems to give about as much airflow as the OEM fan blades now.

Update: Fixed an off-by-one issue in a loop causing the blade to end just above the bed. Thanks to Kevin` o