This is a helical version of Ed Lenz' Lenz2 turbine blade. His homepage is here http://www.windstuffnow.com/main/lenz2_turbine.htm Dimensions: this should give a 120mm diameter, 160mm height windmill. 2013-06-09: Hey look, I made a larger one - http://www.thingiverse.com/thing:99132 31-5-2013: I managed to print the last layer last week and the turbine is now spinning in the wind. I started thinking about making a larger version of this that i can still print on the 200mm print bed. The larger version that i am working on is going to be mounted on a electric bicycle brushless 3 phase hub motor of about 200 Watts. It will also use aluminium arms (20×2mm flat) instead of the plastic ones. The new thing id will follow later. 18-05-2013: Crud, broke the pulley on my 3D printer, posted the picture of it on a wooden stick on the back of my shed. It only has 2 layers now, 3rd one later when I fix the printer. 18-05-2013: Just uploaded a double bearing holder so I can mount it on a 44x44mm wooden pole. The bearings I am using have a 32mm outer diameter. They are not really the correct size for a 12cm diameter windmill. I'm planning a larger one for later. The bearing holder doesn't print very well, word of caution. I've also reuploaded the single blades for 30 and 40 degrees which now have a 1 degree resolution. Same thing, looks nicer, takes longer to slice. Also turns out you can print 3 single blades and a hub on a single 20x20 bed. When printing on scale 1:1 you can apparently print these without support which makes them look a lot prettier. Printing a single blade at 0.3mm height takes about 1 hour 45 minutes here. Printing 3 at once with hub is about 4 hours. Seems like a good deal. 16-05-2013: Uploaded a hex center hub to mount the single blades on. I'll probably add a hex nut cage on it for easier assembly. Perhaps nut cages on the blade mounting hole would make sense too. 15-05-2013: I just uploaded a new single blade with mounting hole which can be mounted on a central. That way you can mount 3 of these for a single 1/3 rotation (40 degrees of 120) 53,3mm high helical form. This allows for making a larger version(s) with the limitation that 3D printers have in build volume. With repetier host you can easily scale a single blade by a factor of 3 to get a 160mm high single blade. That would result in a 480mm high windmill! Still working on the central hub, still evaluating CAD programs to do my bidding. 14-05-2013: I'll be adding seperate blades with different heights and a hub carrier so it's easier to print larger versions with the restricted print bed size. Should have this done this week. I don't recommend printing the entire helix with supports, as these will overlap with the next blade. (That won't be a issue with seperate blades) The model is a bit too complicated for Sketchup, which it also imports every dimension multiplied by 25,4. That means it is doing the unit conversion wrong. That is a issue with the STL importer for Sketchup. These STL files are hole free and should go through Slic3r without warnings.Single Blade If you print the single blade you need 3 blades to make a single level. I've only left the 53,3mm 40 degree turn blade for now. You need to mount these on a central hub with a M3 screw+nut. The central hub is not here yet. That is forthcoming. Layer assembly You can use super glue to glue the layers together. I've added the entire helix as well so people can modify it to print 1/2 height 60 degrees rotation too. The lower height model slices well as it is far less complicated over the entire helix. It also allows for easier printing.