Robo 3d R1 threaded rod stabilizer

thingiverse

This is the stabilizer I built for my Robo 3D R1. Since you're using Z rods that extend to the top of your case, this setup might not work as intended if you have a different model - in which case additional modifications would be necessary. The large hole accommodates a standard size skateboard bearing (608 dimensions). The smaller hole has an 8mm diameter. These pieces are press fit into place during printing, so minor adjustments may be required to get them fitted properly.