I'm building a strat style guitar and forgot to route out the nut slot when the neck was square. What is the best way to hog it out accurately after the fact? I started it with a chisel and it was coming out well but the chisel is just a little smaller than the nut. Too close to go up to the next size chisel but to far to hammer it in. My file is too wide for the slot. I'm thinking my only choice is to hold the chisel side ways and try to widen the wall as if the side was the bottom of the slot. Anyone have a better idea?