This process may look tedious, but to drill a hole in your stainless steel countertop is rather simple if you have the right tools.
The key is to use 135 degree split point High Speed Drills – they can be purchased at most hardware stores, Home Depot, Lowes, etc. Just verify that they are 135 degree split point. Cobalt or special coatings are not necessary, but always use oil to keep the bit cool, otherwise it will burn up (melt down). Place a few drops on the area and/or drill bit as you work your way through the process, adding drops occasionally to keep the area cool.
CAUTION: Always use safety glasses or goggles to protect your eyes
1) Start with a 1/8″ drill (short double ended drills do not tend to break as easy)
2) Step up to a +/_ 3/16″ drill bit.
CAUTION: If you step up too quickly early on, the drill bit may tend to “grab” and your drill will bind.
Speed is not your friend. Use a pulse pressure rather than just laying on the drill all at once. You will get better results and the bit will not build up as much heat. If the bit turns black, change to another one as it will continue to “melt” the cutting edge if you continue, causing a hardened surface (harder to drill through)
4) Continue stepping up until you reach your desired hole size. As your pilot hole gets bigger, you can step up quicker to larger drill bits.
5) If the hole is quite large, i.e. over 1/2″, you can use a step drill bit (Unibit), but you must first start with steps 1 & 2 for proper pilot hole clearance. Again, use oil to keep things cool, and use the pulse method.
6) Debur the hole with aluminum oxide sand paper or a file if necessary.
CAUTION: The chips can be hot and sharp, so be careful as you swipe the area with your hand (use gloves or a rag if needed)
Note: If you have a wood backer already installed, it will not affect the drill bits.
The entire process will take about 10 minutes or so per hole if you have good sharp bits.