Yes, bearings don't seem to come apart from cup so if I was to use my press I'd be applying pressure onto the bearing. Adaptors let you apply pressure onto the outer lip of the cup. So in practice a large washer should suffice (some install videos show this anyway). I'm making the equivalent of that out of thick brass sheet drilled to my press main shaft diameter.
Yes, bearings don't seem to come apart from cup so if I was to use my press I'd be applying pressure onto the bearing. Adaptors let you apply pressure onto the outer lip of the cup. So in practice a large washer should suffice (some install videos show this anyway). I'm making the equivalent of that out of thick brass sheet drilled to my press main shaft diameter.