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Bit Drilling- An Intro

In the production industry it seems there is a lot of just about everything. Certainly, any of us that has bumped into the industry more than a time or two knows there are quite a bit more than a lot of drill bits to choose from. Contrary to some opinion, though, the numerousness of these accessories is not meant to confound us, but rather to compliment our applications and improve our results.In fact, there is a drill bit specifically designed for just about every hole-type and every working material under the sun – this means that for each project or each application you endeavor, you might feasibly require a different drill bit. From metal and ceramics to glass, plastic, marble, wood, and many et ceteras, there’s a drill bit for that. So, let me provide for you the most basic of drill bit basics.


First, although there are hundreds of different bits and different ways to use them, virtually all drill bits are talked about with the same vocabulary. In other words, they’re mostly made up of the same parts:

The Tip:

Moving from front to back, most all drill bits begin with a tip. This is exactly what it sounds like, a tip, usually with a sharp edge or point that begins the working half of the bit. The tip is, more or less, the spearhead of a drill bit and will often act as a self-centering characteristic.

The Lip:

Next down the line are the lips of the bit which are the usually spiraling cutting edge(s). The bit’s lip angle usually determines the temperament or overall aggressiveness of the drilling action.

The Flute:

The grooves spiraling beneath the lips are the flutes of the bit which act as channels for material ejection. As the bit penetrates deeper into a material excess material is forced out through the flutes as the hole is drilled. The bigger the flute, the faster a bit can expel material and therefore drill.

The Spiral:

The spiral of the bit is made up of its lips and flutes and refers to the rate of twist within the working half of the bit. This, as aforementioned, controls the rate of material removal while drilling, and the quality of the subsequent hole.

The Shank:

Lastly, is the bit shank. This is the piece of the bit that fits into your drill chuck. The shank is probably the most boring (as in uninteresting, not to be confused with actually boring a hole) part of a drill bit. It is, however, no less important to your drilling performance. The shank is mostly smooth and roundish and may also contain design features meant to more snugly keep it in your chuck.Each pieces of any given drill bit contributes to the general behavior of the bit. In other words, bits designed for precision work will have a different tip and lip angle than bits designed for more aggressive drilling. Similarly, bits designed for ceramics will structurally differ from those designed for wood or metal.


The above vocabulary gives us another way to discuss and identify our drill bits – measurement. If you’ll remember from geometry, the diameter is the length (through the middle) of one end of a circle to the other. In other words, if you were to cut a hamburger in half, the length of the flat side of your now halfed hamburger would be its diameter.

Shank Diameter and Bit Diameter:

So, the shank diameter is simply the measurement of the end of the shank. Your bit diameter, then, is the measurement of the opposite end of the drill bit – the less boring part, the tip.

Flute Length and Overall Length:

The flute length is the length of the working half of the bit which excludes the shank. The overall length, then, refers to the length of the entire piece – shank and flute included.

Rate of Spiral:

The rate of spiral refers to width of the lips and flutes, or, the amount of vertical space the flute takes up between each lip and the lip takes up between each flute. This may also include the depth of a bit’s lips and flutes.Of course, there are many more types of measurement that are specific to the design of more complicated bits – but, for the sake of basics, this provides a general groundwork that can be built upon as your experience grows.