Use the hand scraper ground at 40 r neg 5 with the neg 5, same as for iron. and hold the handle vertically and pull scrape it. The picture is Ted, my assistant teacher at the Taiwanese research center I taught at. The pull scraper we made out of a aluminum shaft and we bolted a Biax blade to the end. Ted was showing off. PPI was 40 PPI. 20 PPI is good enough.