In lieu of sealed bearings, a flanged washer in front of the bearing would suffice 'pressed' onto the bar being turned. An O-ring or felt seal against the bearing on backside of flanged washer, makes it complete.
Running on bearings is technically a pillow block, with less center height adjustment problems.
This was a common occurrence repairing feed roller shafts; bearings ran in steadies to circumvent turning a clean band on the roller itself. None of those would fit any spindle bore, unless a big turret lathe; inadequate bed lengths for that work.