You can make holes in a many ways. Yet drilling with a drill bit is most known. Bit comes in many sizes, shapes , etc. In order to make holes bits are usually attached to a power drill to cut through the workpiece by rotation. You can drill soft materials with most any drill bit, but hard materials require specially designed tools. Forstener bits, large diameter core bits and other should be used with a drill press. But most of tools can be used with a hand power drills.
Step drill bits are one of the more popular tools for drilling in soft and (or) thin sheet metal. They work at a faster speed to make relatively clean holes. Step drills come with just one single drill bit with progressively sized grooves and ridges. So you just need one tool for a variety of jobs. But you should avoid drill wood with unibit because the bits split the wood and the hole will be low-quality.
One major aspect of drill bit selection is the material makeup of the drill bit itself. Any material work good with the applications for which it is designed. Low carbon steel is soft and dulls quick when drilling hard metals, but they cut wood great. High carbon steels require less sharpening, and hold their effectiveness longer. High carbon tools also can easily cut woods. HSS is a type of carbon steel with more complex alloys and it can withstand higher temperatures. High speed drilling causes heating and temperatures can raise dramatically, but high speed steel can undergo it. Tungsten carbide alloys are tough, but brittle and more expensive. This material is used to drill hardened and stainless steel.
Longer bits can drill deeper holes, but they are more flexible, the drill may have an inaccurate location or wander from the intended axis. Usually bits are available in a standard lengths: short length, most common Jobber-length, and long bits. Two or more spiral grooves that run the length of the drill body are called flutes. They need to curl the chip for easier removal, remove them from the cutting edge, help the lubricant flow down to the cutting edge.
Grinding a conical point with a flat surface to create a linear chisel helps to reduce the thrust and improve the process of cutting and removing the chips. In modern automated drilling metalworking machines multi-faceted drill points are widely used. They require 50% less thrust, and generate 60% less heat.
The general purpose drill points are usually 118°. They are typically used for cutting into soft metals such as aluminum, whereas the 135° variant is best suited for hardened materials, such as stainless steel. A 135° drill is flatter than 118°, which means that more of its cutting lips engage with the material surface sooner to begin the full metal cutting action.