There is also the cup burr. This is probably my most favorite way to get a nice finish on my ear wires. A cup burr, when used correctly, will round off the end of your wire. It is very important to use lubricant to make the cup burr more efficient. You can lubricate either the wire or the cup burr, as both works well. After using the cup burr, feel around with your fingers from all angles to see if there are any rough edges. If there are, you can continue to use the cup burr or use the file or sanding/polishing paper.