Moderator Post (s) for this thread: >Step drillbydoug seibert on 11/24/2009
Hi, Joe. Drilling stainless is very difficult. The only way to do it is to use cobalt (Not carbide) drills. Since these are expensive and not generally available in larger sizes, the plumbers have punches that they use for big holes in stainless. So the first thing to do is to go to or call some specialty plumbing supply houses to see if you can buy or rent the punch in the size that you need. The next thing is to go to an industrial tool supply house and buy a cobalt drill in the size you need for the lead screw on the punch. This is the tough part and using it is easy. Locate where you want the hole. Punch a center for your drill so it doesn't wander and drill a hole for the lead screw. Install the punch, preferably so the burr will be pulled to the bottom but it is OK if the burr goes to the top by putting the lead screw through the small hole and tightening the nut. Use a wrench to tighten the nut and punch a big hole in the stainless. If you had to pull the punch up because of clearance for the wrench or whatever, put a grindind stone on your high speed rotary tool (Dremel)and grind off the burrs being careful not to mark the rest of the sink.
Drilling and punching the hole takes less time than describing how to do it and I'm sure that you will understand when you see the punch tool. Ah but finding the punch tool, that will be the problem.