DIY Impact Mill/Rock Crusher - Crush Anything (Gold Ore, Circuit .Oct 11, 2015 . I built an impact mill that will crush a 4" rock into powder in under 1 second. This rock crusher is also known as a chain or a flail mill. I also run some a.crusher for gold mining,HOW TO BUILD A ROCK CRUSHER !!! Impact Mill For Gold Ore .Aug 26, 2013 . Watch as The Good Doctor ( ask Jeff Williams ) shows How we Built our Rock Crusher ( Impact Mill ) to pulverize Gold Ore down to 100 mesh to run over a s.