Spool holder with printed ball bearing body and 6mm airsoft BB pellets

thingiverse

Can handle 1kg or smaller spools up to 75mm wide(from center of the edges of the spool). The bars and spool holder print at .2-.3 mm thick layers, the bearing inner and outer body with no larger than .15mm layers (first layer can be thicker if need be). You will need 4x of each of the bearing pieces so you can make 4 bearings total. If printing them all on one bed, use the complete one object at a time function so you get much better seams. You need the two 91mm bars and one of the spool holders. The 91mm bars might need to be scale in terms of size of the pentagon (don't scale the length if you do) depending on your printers tolerances. I have a .1mm tolerance for the fit of the rods into the spool holder and bearing holes. The holes on the spool holder and the 91mm bars have no tolerance, so it is a tight fit and might require some sanding or scraping. Scaling the two coordinates that are the face of the pentagons to 98 or 99% will help if you need a small tolerance and don't want to do any post other than some stringing and/or zit removal. Finally, to make the bearings, simply take the inner body and outer body, and place 8x 6mm airsoft BB pellets into the slot for each of the bearings. I like to have the slots on opposite sides so that I need to force the pellets in a little harder and have no chance of the BB's falling out while in operation. Credit to StreetPiet for the ball bearing design, I modified them to have the guides on the outer body for the edges of the spools as well.