Toolsday: Drill Bits

Last week, I discussed a tool that could be used as a drill, so I figured I'd talk today about drill bits.


Drill Bits

It's important to remember that drill bits have two relevant dimensions. They have a diameter of hole they drill, and a depth of hole they are capable of drilling. Thicker drill bits are usually capable of drilling deeper holes. A good selection of drillbits has a wide variety, in very small increments. This set goes all the way from 1/16 inch to 11/32 inch in diameter, and from about 1 inch to 5 inches in length. (I'm not counting the "shank" portion of the bit, which is the part held by the drill itself.)

These are coated in titanium nitride, which is a long-wearing alloy that helps them staty sharp longer. I bought this set at Harbor Freight, which means they are not the best quality, but they didn't cost as much. They came in this nice metal index box, which stores all those drill bits in very little space. They are standard "twist" drill bits, meaning that they are best suited for metal or other solid materials. I wind up using them pretty often on wood, though they sometimes tear out some extra wood when starting holes, because of the grain. They give me the most versatility when drilling pilot holes for screws, though.

That's what I mostly use drill bits for. If I drive a screw or nail into wood without a pilot, quite often the screw will break, or the wood will split. Drilling a smaller hole first allows me to control where the fastener goes, and removes some of the material that the fastener would otherwise be pushing out of the way. It's important to leave enough material for the fastener to grip, though. That's where this kind of bit variety pays off. For instance, they say you should drill a 1/8 inch hole for a #8 screw, but having this variety lets me drill a 3/32 inch hole instead if the wood is softer.

I should talk more about the different kinds of drill bits I own and that exist. There are more than you might expect.

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2010.10.05 at 12:00am EDT