I was asked about blades with one piece.
This blade model is 177mm hight so you´ll have total diameter 40cm fan with centerpiece.
-Blade is solid piece with leg.
-Spinner has center pole and 1.2mm skin.
If you scale its wise to do scaling to all three parts.
Now I have a some higher printer so this is getting exiting - I think I can reach between 60 and 70 cm fan with one print...
These are my first trial:
I sliced it vertical position with settings
0.4mm layer height, 2 perimeters and infill 10% (honeycomb 30°)
To get more solid base feet for size 400 I used 50 solid layers.
For my speeds cooling fan is clearly needed with PLA.
There is clearly some difficulties with printing a sharp trailing edge so I used file and some water resistant sand paper there. If you want to make it perfect also some filler/paint might be necessary - with those treatments I think it not necessary to print this with high resolution in vertical position - that make things so much faster.
I updated the spinner stl part. I got too much faults.
Also printed this with USB so some jaggered print). Hexagonal piece is solid with center holes etc are close to M5 size (without scaling of course).
Some day I will try all the diameter 645 blades and parts in a one print. Scale 1.612 gives blade height 285mm and propeller diameter about 645mm. For size645 80 solid layers on bottom might be good. With Slic3r 1.0.0RC2 select part and settings in UI right upper corner - there is option for solid layer number for selected part so you can separate solid layer height in different parts.
Scaling does not change the angle of attack so I suppose efficient RPM will go down. This design goal is to have slowest fan rotation, but might be wise to check the design some day - the blade root cord length seems quite narrow as a fan and might "leak" also the tip is not finalized... This might be that the design program was quite basic and restricted with propellers - It would be nice to have other efficient and quiet fan designs also.