Different Sizes of Drill Bits Explained

assortment of drill bits

For just about every conceivable job requiring a bored hole into brick, wood, light metal, tile or glass, drill bits of differing size and shape are essential for the task. When used with either a power drill or a drill press, the different kinds of drill bits offer a solution to any drilling need. Carpenters, contractors and do-it-yourself enthusiasts alike benefit from having an assortment of drill bits at their disposal. As you will learn, there are numerous types of drill bits, each with their own specific use, and each type comes in many sizes.

1. Drill Bit Set

A standard drill bit set consists of several twist bits in consecutive sizes, ranging from 1/16 of an inch up to 1/2 inch in size. A twist bit is your standard drill bit: cylindrical in shape in a double helix pattern with a sharp, pointed tip. Twist bits are the most common type of bit employed to drill holes of varying sizes into wood mainly. They can also be used for less dense materials like PVC or drywall.

A drill bit set provides you with the basic sizes that are most commonly used, and they work well with power drills. Twist bits have a cylindrical shank that fits straight into the chuck of the drill. While there are bigger twist bits, they are often used for specialty applications. There are different types of drill bits you can use to drill bigger holes.

2. Paddle Bits

paddle bits

Paddle bits are flat, square-ended bits with a pointed tip jutting out the bottom. They resemble a paddle with a sharp point attached to the end of it. They are used to drill larger holes in wood, usually after a pilot hole has been drilled with a twist bit. Paddle bits generally range in size from about one inch up to two or 2 1/2 inches. Holes larger than that typically require a sturdier bit.

3. Hole Saws

Despite their name, hole saws are bits that can fit into the chuck of a power drill or a drill press. They are shorter, but broader hollow cylinders with a bottom edge covered in teeth. Whereas paddle bits bore out the wood when making larger holes, hole saws simply cut around it, making the hole while leaving you with a circular piece of wood. Hole saws can get quite big, up to four inches in diameter or more, but the bigger bits usually require a drill press.

4. Forstner Bit

forstner bit

This type of bit is used when you don’t want to go through the wood, just into it. Its shank is cylindrical like a twist bit until you get to the working end where it flairs out into a short but wide cutting area. You could say it resembles a flat, wavy-capped mushroom. Forstner bits are ideal for setting holes to a particular depth in wood rather than drilling through them. They leave a flat bottom in the wood that is cleanly cut.

5. Countersink Bit

A countersink bit can look like a twist bit until halfway up the shaft where it tapers out, looking like a top with a standard drill bit right through the middle. The other type is just the top-like bit with its own shank. Either way, it is meant to bore a concave conical shape around the hole you drill so inset screws sink below the wood’s surface.

There are other bits for masonry, tile, glass and steel, but they are essentially the same as twist bits. They differ in the materials used for the cutting edge.