Duplo rotating parts, rotors for helicopter / Duplo Drehteile, Rotoren für Hubschrauber

Here is a collection of rotors for duplo. A big one for a helicopter as well as two small ones for a turntable ladder, crane etc. One of the small ones has rounded edges at the upper part, so that it won’t collide with knobs of neighbouring bricks.

You will need a FR4-ZZ Miniature Flange Ball Bearing with inner diameter d = 6.35 mm / 0.25 inch, outer diameter D = 15.88 mm / 0.625 inch and a height B = 4.98 mm / 0.196 inch. You can get them for about 2€on ebay or so. If needed you can glue the bearings into the parts, especially the inner hole to the knob of the Rotor-bottom-part.

No support needed because of the chamfers in the lower part. Where the bearings have to be put in, perhaps some filament will hang down, but this can easily be removed.
I printed with a 0.4 mm nozzle using 0.35 mm for slicing. Perhaps different slicers or nozzle diameters will produce different wall thicknesses. So it could happen the parts won't fit that good with the other duplo parts. I hope this will not happen!