Spacer for Delrin V-wheels

My Mini Kossel uses machined Delrin wheels that run in the slots of 1515 extrusion. These wheels each hold two 623zz bearings, but it is impossible to grip them tightly on the shaft because they are supported only on one side. Tightening the nuts applies shear to the bearings, which can ruin them. This spacer goes between the pair of bearings and holds them apart so that you can tighten up the nuts on either side; the inner races then bind firmly between the nuts and spacers, while the outer rac