I think we're basically agreeing with each other!
To come back to the OP, Madge asked about whether a 40 micron lapping film was too fine for what she needed, but that is only equivalent to a p360 oilstone, which is not really engineering levels of fineness anyway....
My preferred method for flattening is to use standard aluminium oxide paper on a flat machine table and use that with a bit of oil. Starting at p60 and working up from there is pretty quick and saves the stones. I'm nervous about using the side of the wheel as I got told horror stories when I was training....
To come back to the OP, Madge asked about whether a 40 micron lapping film was too fine for what she needed, but that is only equivalent to a p360 oilstone, which is not really engineering levels of fineness anyway....
My preferred method for flattening is to use standard aluminium oxide paper on a flat machine table and use that with a bit of oil. Starting at p60 and working up from there is pretty quick and saves the stones. I'm nervous about using the side of the wheel as I got told horror stories when I was training....