Hi,
Hand scraping is a useful technique to go from 0.01mm to 0.001mm, but any suggestion that you can remove as much as 0.1mm is a joke....you'll be there forever. Milling or grinding to within at least 0.01mmBut even then I assume I can only get ±0.02mm flatness using hand scraping,
is the answer, scrape if you think it will add anything but don't imagine you can remove any large volume of material.
Craig