سنگ فرز

Also known as sharpener, grinder

upright|thumb|The Knife-grinder by Goya shows a man using a portable grindstone. thumb|Two lumberjacks using a hand-powered grindstone to sharpen an axe during World War I A grindstone, also known as grinding stone, is a sharpening stone used for grinding or sharpening ferrous tools, used since ancient times. Tools are sharpened by the stone's abrasive qualities that remove material from the tool through friction in order to create a fine edge. Similar to sandpaper, each stone has a different grit that will result in sharper or duller tools. In Australia, Aboriginal peoples created grindi