Making iron oxide fast?

I have looked up many ways to make iron oxide but they take several days to a week. i also found that when using a ball mill that the metal will start to oxidize if it becomes too fine. so if i wanted iron oxide then theoretically i could get a piece of iron and use a grinder on it and put all the particles in a jar with vinegar, water and a little salt and it would produce rust much faster due to the increase of exposed surface area. Can anyone verify this?