Velleman Vertex K8400 Bearing Clamp with bigger hole
This bearing clamp is modified with a bigger hole for an experiment from somebody on the Velleman forum. The idea is to fit a plain shaft bearing (10mm outer, 8mm inner like the rods) into the bearing clamp so the distance between the bearing clamps can adjust, what causes less headaches for getting a smooth movement. You will need only one per axis. Follow the thread for more information :