The 1.000 in dia main shaft rotates in two Barden, 25 mm (.9843) X 47 mm (1.8504), ABEC-7 bearings, with precision machined riveted aluminum cages. The ground shoulder at both ends of this shaft allow the main shaft assembly to be preloaded. Notice at the base of the front main shaft bearing housing how it is keyed to the base. It is also doweled pinned for easy re-location when assembling the unit.
