Drill Bit Types, Prices, and Purpose

This is the most basic tutorial on drill bits. To learn which ones to buy for your very first construction or hobby project, read on. For more advanced information, explore the links on this page.

An absolute beginner in construction who intends to make just a few holes at home, should buy a cheap drill bit set and not bother with anything else. A large drill bit set purchased online at a discount, like this Black & Decker 71-622 122 Piece Drill & Drive Bit Set, will set you back $25 and cover all your occasional drilling and driving needs for years to come. These drill bits are lowest grade possible, and can not withstand any kind of regular use. They are easy to break and lose their cutting edge very fast. Driving heads included in such sets are also not intended for tough jobs. But the benefit of having a set like this is that you have a tool handy for virtually any occasion, and if it breaks – oh well, it only cost you 20 cents apiece.

If your project involves a significant number of holes, you will need to purchase high grade drill bits specifically for the project – or several identical low-grade ones, which is also a viable option, especially if your virtuoso drilling style requires an unbroken drill bit for every other hole. The easiest way to find out exactly what you need to purchase is to drill a test hole with the bits that you have in your cheap drill set, and then note the marking on the bit that fits (it is written on the shank, hardware sales people will know what you need if you say “8 drill bit” or “#7 drill bit”). You can also take that bit to the nearest hardware store and demand a better version of it.

What you need to purchase depends on the type of material you intend to work with. The regular twist drill can handle most materials except masonry, but is primarily intended for metal. It is also ok for shallow holes in softer materials such as wood and plastic, but if you need to drill deeper than two diameters of the bit, it will get clogged. Bits specially designed for wood don’t have this problem, and are also easier to center. This type is called lip and spur drill bit, also known as the brad point bit or dowelling bit. For larger holes in wood, spade bits and Forstner bits are used. Another special type is called masonry drill bit and has a tungsten carbide tip which is very hard but not particularly sharp. It can withstand hammering reinforced concrete, but can not cut, so it can not be used on other materials. Glass drilling also requires special bits. If you have choice, always use diamond glass drill, not a carbide drill bit. If you need to enlarge an existing hole, use a core drill.

When working with hard materials such as steel and masonry, a drill sharpener such as Drill Doctor may come in handy. The simplest model Drill Doctor DD350X Drill Bit Sharpener is available online with a discount at about $50 and can save you quite a bit of frustration when your last drill bit breaks in your last but one hole on Sunday evening. It will eventually pay for itself, too.