Hmmm....that's what I was afraid of. I like the approach of the holes on either side. I tried to do it with just the plunge cut but because of the radius of the cutting wheel the edges of the hole were tough. The two holes will eliminate that.Hole on either end- two plunge cuts with a Dremel cutoff wheel. Line up the cuts with the outer edges of the holes you drilled. Minimal deburring with a file. The metal cutting but will wander badly- and create a sharp and ragged slot that's hard to clean up and make right