Parametric marble roller bearing for cheap filament spindle (Q46620)

This is a derivative work of http://www.thingiverse.com/thing:4641 and http://www.thingiverse.com/thing:4885 . It is designed to be Makerbot printable. The idea is to have the roller bearing filled with marbles and have some board with the filament on top of it freely spinning. For the board you can use cardboard, press board or whatever is lying around. I used some of the wood left from the makerbot assembly. To increase resistance against tilts and asymmetries in the filement spindle it is desirable to print the parts as large as the build area of the printer allows. There are two variations of this thing: (1) marble_bearing_simple.stl: the simple approach with the same grooved ring below and above the marbles. Should print quite fast without problems on any 3d-printer. (2) lower_part.stl & upper_part.stl: the somewhat advanced version. To avoid the marbles rolling around evrywhere if you touch the spindle they are enclosed in the bearing. Both of the designs tolerate quite a lot of load on top of them, i wasn't able to destroy them by staying on them - so maybe they are also useful for rotating heavy things like plants, cabinets ... or a makerbot ;-) Each of the above variation requires in addition up to 12 marbles with 16mm diameter. The scad-file of variation (2) is parametric, so you can tune it for different marble sizes and different radius (e.g. if you have a larger build area). If you do not have marbles at hand you can also print them using marble.stl . This is a version with some minimal support to avoid the marble rolling around during the print. It might be possible to print them without any support if your printer is well adjusted.