What is the best way to make a one and a quarter inch diameter hole in a stainless steel sink?

Answer 1

Arguably the "best" way is with a knockout, cabinet or chasis punch. Electricians us them to punch holes in electrical boxes and cabinets. They come in various sizes, and are simple mechanical types, or hydraulic ones. The main components are a punch, a die, and the operating shaft. The shaft is threaded, and after a pilot hole is drilled for the shaft of the tool, the punch is assempled (through the hole) and a wrench is used to tighten the punch until it cuts through the metal (in the case of the non-hydraulic kind). You may be able to rent or borrow one. It is kind of silly to buy one for a single hole, but they puppies are the bomb for punching out a big hole like is suggested. It might be possible to rent or borrow one for a short time. Stainless steel is notoriously tough. You'd damage a hole saw doing the job, probably. It is possible to use a jig saw to make the hole. With a bit of time and patience, it can work. A heavy metal "nibbler" might work, but you'd have to find some way to finish your work to clean up sharp edges. The jig sawed hole might need a bit of cleaning up, too. If a picture is worth a thousand words, use the link and have a look at one on the Greenlee web site.