Filament Spool Holder with bearing

Hi,
yet another spool holder. This one is mounted directly to the frame of my Sparkcube 3D Printer. If you have a simmilar frame design (using cubic mounted 20x20 type B Aluminium profiles) you can use this spoolholder as well.
The fixation is done using M4 DIN912 screews and the fitting groove nuts. The appropriate spaces left for inserting the nuts is only for the use with cheap M4 groove nuts.
The bearing used is a radial ball bearing with a diameter of 19 mm.
If you need more infor