Silverline 612120 Lip and Spur Drill Bits 3 mm Pack of 10
About this deal
Cobalt steel alloys are variations on high-speed steel that contain more cobalt. They hold their hardness at much higher temperatures and are used to drill stainless steel and other hard materials. The main disadvantage of cobalt steels is that they are more brittle than standard HSS.
Bits are commonly available in sizes from 8–50mm (0.3–2.0in) diameter. Sawtooth bits are available up to 100mm (4in) diameter. Another, different, bit also called an installer bit has a very long flexible shaft, typically up to 72 inches (1.8m) long, with a small twist bit at the end. The shaft is made of spring steel instead of hardened steel, so it can be flexed while drilling without breaking. This allows the bit to be curved inside walls, for example to drill through studs from a light switch box without needing to remove any material from the wall. These bits usually come with a set of special tools to aim and flex the bit to reach the desired location and angle, although the problem of seeing where the operator is drilling still remains. The diamond masonry mortar bit is a hybrid drill bit, designed to work as a combination router and drill bit. It consists of a steel shell, with the diamonds embedded in metal segments attached to the cutting edge. These drill bits are used at relatively low speeds.
Spurs First: Start with the spurs of the drill before moving to the point. It should only take a few strokes to properly sharpen the spurs when kept at the correct angle. The same is true when using a grinder.
These core drill bits are similar in appearance to reamers as they have no cutting point or means of starting a hole. They have 3 or 4 flutes which enhances the finish of the hole and ensures the bit cuts evenly. Core drill bits differ from reamers in the amount of material they are intended to remove. A reamer is only intended to enlarge a hole a slight amount which, depending on the reamers size, may be anything from 0.1 millimeter to perhaps a millimeter. A core drill bit may be used to double the size of a hole. Todd, Robert H.; Allen, Dell K.; Alting, Leo (1994), Manufacturing Processes Reference Guide, Industrial Press Inc., pp.43–48, ISBN 0-8311-3049-0.If you can’t drill the wood without pushing hard, return to the grinder until you achieve the desired results. 7. Use Your Drill to Test It