It’s not an official rule of hand-drill operation, but it’s one worth heeding anyway: When drilling a hole in something, don’t inadvertently drill a hole in the something behind or under the target something. Could make for an expensive mistake.
There are, however, tools designed to prevent such screw-ups. They’re called drill stops, and the set pictured here from Graham Tools (www.grahamtool.com) is a prime example. There are seven stops in this set (part #DSKIPB, $20) in standard drill sizes ranging from 1/8- to 1/2-inch. Each is simply a thick steel collar slotted on one side, with an Allen pinch bolt spanning the slot; the kit also includes the three Allen wrenches that fit the pinch bolts. After you determine the diameter and depth of the hole you are about to drill, choose the stop that fits the bit, position it on the bit according to your depth measurement and tighten the Allen screw to cinch the stop in place. Then just drill to your heart’s content without having to worry about poking an unwanted hole in that other, uh, “something.”
I own a less-expensive drill-stop set and have seen several lower-priced examples on the market, but I like the fit and feel of these. I’ve used them to drill quite a few depth-sensitive holes for numerous projects, and they’ve never failed to prevent me from accidentally ventilating an important component.
