Metal Hole Punch Video
In this project, Tim wants to convert a copper bowl into a bathroom sink. The problem is there is no drain hole in the bowl. To get a perfectly round hole in a piece of metal, you will use a hole punch or knockout punch. Using a series of smaller to larger hole punches is the best way to make a large diameter hole.
First, drill a pilot hole at the center of the desired location. The pilot hole should be just larger than the bolt on your hole punch. Insert the bolt with the one side of the knockout punch through the hole and thread on the cutter side of the hole punch onto the bolt.
Use a wrench on the drawbolt to pull the cutter through the metal. Continue tightening until the cutter breaks through the metal. You can then, just lift the cutter through the hole.
The first hole should be larger then the bolt size on the next knockout punch. Repeat the process with the larger cutter. This will allow you to make the hole in the bottom of the bowl match the size required for your sink drain.