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<p>There are many ways to drill a hole in something. But the most common is drilling. Manufacturers offer many types, shapes, materials, sizes of tools. Drilling usually is done with a powered drill which cuts the material by drill bit rotation. You can drill soft materials with most any drill bit, but hard materials require specially designed tools. Forstener bits, big diameter core bits and other should be used with a drill press. Others are good enough to use with hand or even hand-powered drills. </p> <p>Any master working with a sheet metal, boxes or thin mild metal has a Step drill bit (Unibit). 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. With the tool you need one tool for a variety of jobs instead of many twist drills with various diameters. The one thing that you should avoid using step drill bits on is wood because they are known to split the wood. </p> <p>You need longer bit to cut deeper hole, but they may wander or may have an inaccurate location due to their flexibility. Usually bits are available in a standard lengths: short length, most common Jobber-length, and long bits. Flutes are two or more spiral grooves that run the length of the drill body. They need to curl the chip for easier removal, remove them from the cutting edge, help the lubricant flow down to the cutting edge. </p> <p>Drill bit coatings are intended to lessen friction, wear, and prevent rust. ZiN - Zirconium nitride film adds the strength, decreases friction and improve heat removal. Titanium coating is strong, adds corrosion resistance. Titanium also is heat-resistant and has an excellent fatigue limit. </p> <p>The general purpose drill points are usually 118°. They work well for cutting into copper, aluminum, and mild steel, whereas the 135° drill point is good for stainless steel, hardened steel and another tough materials. 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. </p>
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