Bver tried to cut something with a pair of dull scissors? How about shaving with an old razor? Cutting or trimming with anything that isn't as sharp as it's meant to be is no fun-and the same goes for those drill bits we're constantly wearing down. Once a bit loses its cutting edge, the job it's intended to do becomes much harder to accomplish, and nobody enjoys spending the extra time (and labor) it takes trying to work a drill through material with a dull bit. I know I don't.
Up until recently, though, my collection of drill bit sets was so large that I had duplicates and often triplicates of all the bit sizes I commonly used because my older bits were worn out, and in some cases the tips had broken off. Now, the quality (actually, the lack thereof) of the bits themselves played a big part in that, but I could have saved all the time I'd spent buying new bits or even complete sets by spending that money on a Drill Doctor sharpening machine.
Like many of you, I'd heard about the Drill Doctor but never bothered to check it out (had I long ago, I'd probably have a lot more room in my toolbox). Whether it was disbelief it really worked or just fear it was too expensive, I can't really say, but after using it just once and seeing what a number it can do on the dullest of dull bits, I'm just sorry it took this long to see the light. By no means am I spokesperson for Drill Doctor or its manufacturer (I paid for the damn thing!), so I'm not regurgitating their catalog or instruction sheet verbatim. However, when I discover a tool or aid that I feel will be beneficial to others, well, what's the point in keeping it a secret? For me, there's nothing quite as frustrating as a drill that won't drill, so next to having the right power tool (cordless, press, etc.) in proper working order, having truly sharp bits is something every DIY enthusiast ought to have access to.
Along with being a Drill Doctor freshman, I'm also a relative newbie when it comes to drill bit particulars. While I'm pretty comfortable with the difference between metal, masonry, and wood bits, until just recently I wasn't that familiar with varying types of each bit-just which ones worked and which didn't. After becoming acquainted with my new sharpening device, I learned the difference between standard twist bits and split-tips, 118-degree and 135-degree tips, and different materials and coatings that bits utilize for specific uses (some examples are shown in the photos). For instance, the titanium nitride-coated bits (gold in color typically) are designed to cut faster/easier, and the coating actually acts as a self-lubricator; carbon steel bits are specially ground for cutting wood. I'm sure I've ruined a number of the latter bits attempting to drill through metal in the past-until now.
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With the exception of working with bed wood (or any other possible wood related to a truck project), two out of the three bits pictured here, don't typically concern us. To the left of the masonry and flat wood bits is the most common type: the standard HSS (high-speed steel) metal bit. Now, even though we won't be dealing with masonry bits here, the Drill Doctor is capable of sharpening these types as well. | 
My lazy man's tool-the convenient UniBit. They're not real cheap price-wise, but considering what they can do, they're worth the money to me. However, if you damage the pilot tip beyond needing basic sharpening, they're not useless, but they're really only good for enlarging existing holes. |