The original inner cones were threaded onto the wheel spindle, and these have been obsolete for very many years. If you look in Technicalities there is a drawing for a modified spindle to take off-the-peg bearings, ( RMS5 ).The new spindle incorporates shoulders to act as a bearing stop, and the inners of the bearings are tightened onto them. The Nottingham Engineering Products mentioned by Orgasmatron is the same firm as Rollerball Bearings, that I have detailed previously on this website.
Brian
