Cutting a hole in SS sink.

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What's the best way to do it?  I'm putting in a Costco RO system.  I've seen where some in newsgroups recommend doing it with a Greenlee punch but the drawback is it leaves the surrounding metal a little 'wavy' from the stress of the punch.I saw a Culligan guy do it with a drill of some sort on my parents sink many years ago.  I think I'll do that but not sure what kind of hole saw or if I need to use something else.Thank yee!
Reply:Hmmmm, this may get me contradicted but here's what I would try if I had it to do:  I have an abrasive 1 1/4 inch holesaw that I bought at a ceramic tile supply for boring holes in the tile for faucet stems.  Cost me $18, I think.  There should also be smaller sizes available.  You will need to change out the pilot bit because it comes with a masonry bit in it.  I think that would allow you to cut SS without snagging in the thin material.  But I would also use some rubber-footed woodworker's clamps to secure a hardwood block under the spot, then carefully drill your pilot hole, beginning with a small bit (1/8th" or so) & work up to the required 1/4" pilot.  It might even be worth clamping a block on both sides, but use oak or a hardwood equivalent.  This helps protect the adjacent surface from warping or tearing.  If you use two blocks, ditch the rubber-foot clamps & go to all steel.  And of course, pre-bore the top block with a regular holesaw as the abrasive will just clog & smoke on wood.  Be aware that an abrasive bit will likely be a little bit inexact in actual diameter. You might want to do a test hole on some sheet metal scrap;  I probably would.
Reply:Cutter is quite right.Carbide Grit holesaws will go through stainless more reliably than anything else. We used to use these a lot on catering equipment. Stainless steel can be pretty unpredictable to cut, some stuff will cut ok with standard HSS holesaws ( the type with teeth ) others will strip the teeth off in a few seconds.Grit blades will cope with any type.A couple of tips;Spray water on the blade as you are cutting. This will stop heat build up "blueing" the steel around the cut.Re grind the pilot drill with a VERY shallow point - almost flat. That way it is less likely to spiral into the sheet when it breaks through. Hope this is some help.I'm not very clever,But I can lift heavy things.
Reply:Originally posted by one_rod Re grind the pilot drill with a VERY shallow point - almost flat. That way it is less likely to spiral into the sheet when it breaks through.
Reply:Everybody is on the right track here - definitely use an abrasive hole saw.I just had new engineered quartz countertops with an undermount stainless sink installed in my kitchen.  All three holes for faucet/sprayer combo, soap dispenser and Instant Hot water were drilled through the countertop and sink flange together after installation.  Engineered quartz is 93% quartz and 7% resin, 1 1/4" thick and 70% the hardness of a diamond, so it required a 1 1/4" diamond abrasive hole saw, some water as a lubricant,  and patience.  I have to admit, I didn't do it myself, just watched my contractor drill it.  I did all the plumbing and hookup afterward.The hole may be slightly oversized as Cutter pointed out , but the flanges on the faucets, soap dispenser, etc. will cover that.  The soap dispenser plastic  bottle neck was a bit small to stay centered in the hole, however a few wraps of adhesive aluminum tape around it resulted in a snug fit. Attached Images
Reply:Originally posted by Doggus Thanks for the tips everyone.  One_rod, not sure what you meant by this...sorry, I'm with stupid.
Reply:You can use any bi-metal hole saw to cut through stainless steel. The thickness you are cutting through will be very easy. Use a little oil with the cutter. I have cut many holes through stainless steel from 20g. up to 1/8" thick. You will need a 1/4" pilot hole first.J P Streets Welding LLC
Reply:We use diamond hole saws to drill through SS sinks(and tile,and granite countertops) sometimes. I had a couple of used SS commercial sinks that I put in my garage and the holes weren't quite big enough and I used my plasma cutter to enlarge them. I wouldn't do this on  my kitchen sink though. It worked pretty well,turned em a little blue around the hole.DavidDavid