... livestock-powered principle1. grindstones introductionThe principle of livestock-powered was inspired by a fram tool- grindstones. Grindstones also called roller,a main ... tool that use for milling rice and dough. Consisting of by millstone's , stone roller and grind box. This farm ... meters ,so according to donkey,s move shall be caculated by diameter about 4 meeers . Circumference formula C=2∏R get ...