1. First, take out the twist drill bit and mark the places where the twist drill bit needs polishing with a marker. See the figure below for details.
2. Next, start the grinder and clean the surface of the grinding wheel with a blade, as shown in the figure.
3. Put the twist drill bit on the edge of the grinding wheel for grinding, and pay attention to safety, as shown in the figure.
4. Finally, you can polish the twist drill, as shown in the figure.