It's All About H2O
Some people will tell you that drilling crisp, accurate holes in the harder grades of stainless steel is pretty darn problematic if not impossible. They’ll tell you that you need to have extra-sharp, extra-hard, extra-expensive drill bits. And even then, they’ll say there are no guarantees. Which is quite discouraging, truth to tell, particularly if you know what it’s like to crank up a weekend project on a nice Saturday morning only to find out that you’ve already broken a very pricey and necessary chunk of equipment, a development that means yet another time-consuming, wallet-hammering trip to the chandlery or hardware store.
All of which is a pile of baloney, of course. Drilling holes even in exceptionally hard stainless is fairly easy, even if you have comparatively simple, low-tech tools. The key is keeping the production of friction-generated heat to a minimum, either with cooling pastes and liquids or—believe it or not—plain ol’ water.
Here’s how. Start by using a center punch and a hammer or mallet to mark the spot where you need to cut the hole—let’s say, for argument’s sake, you are shooting for a 1/2-incher. Then use a bit that’s considerably smaller than the hole you want to ultimately cut—a 1/8-inch or a 5/32-inch bit would constitute a pretty good bet in this case—and start cutting with your drill at approximately half speed, with medium pressure. The point here is to apply enough revs and pressure to prevent binding but not so much that you produce temperatures that nix the bit’s temper or hardness.
Here’s the trick, however. Once your bit’s made an entry and a few cuttings have been swept aside, dip the bit in a cup of water to cool it off and continue doing so every 10 to 15 seconds until you’ve finished the hole. Water’s the coolest coolant in this kind of situation because it’s easier to work with and clean up than cutting oil or paste. Moreover, you’re most likely going to be using a middle-of-the-road, black-oxide-coated bit on a task like this, not a rarefied, high-speed tool that’s seriously pricey, so repeatedly dousing the thing in water is no big deal.
Once you’ve completed your pilot hole, simply switch to the 1/2-inch bit and keep on keepin’ on, while dipping the bit periodically as before, until you’ve cut the hole you wanted to cut in the first place.
Capt. Bill Pike is deputy editor of our sister publication Power & Motoryacht magazine.