anyone stumbling on this video, his demonstration is wrong. This gentleman's video is a much better tutorial: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-OPGkLtgLCrs.html Burnishing should be done before the diamond is added. The whole point of burnishing is to work harden the copper surface so the diamond does not embed itself all the way into the soft copper. The diamond need to be stuck in the copper but sticking out enough to cut your work without leaving copper streaks in that work.
you can also use an agate burnisher, (much cheaper than a Norbide stick) which is fine, because it is still quite a bit harder than copper and will still burnish the copper..
Thanks for going into the details as you did. Question: I noticed you changed the speed a few times. Being a spinning circle the actual speed is low towards the center and increases towards the edge I would think you could use a higher rpm when your pressing in the central zone then lower your rpm's as you work towards the edge. I guess the question is just how much speed matters, maybe not that much? If a faceting machine were like a belt sander then it would all be the same.
Better to separate the grit are still harder then thenbearing so it could in theory embed onto the lap as well as the bearing but make sure your lap should be softer then the mateeial thay you are gonna lap and the charging tool should be harder then the lap plate or as hard or even harder them the lapping compound
