I been sharpening by hand since the 90’s .I also have a background in machining . Lynton McKenzie shows his method in a video. I basically use his example. I know my sharpening is correct because the tool runs straight, stays sharp a long time. As Lynton said optical flats are not needed to...
I sharpen the face first, jab it in wood to remove the burr, for the heel I use fine ceramic stone & strop on hard leather loaded with Tripoli or other polishing compound. I use these in Belgium style steel handles. I do this sharpening by hand. Good luck