4/28/2023 0 Comments Drill bits for metalSo if you have a cordless drill, use this instead of a mains corded drill. Small bits often break when they snag or catch in the workpiece.A lip and spur (brad point) wood bit is best for drilling plastic. When drilling plastic, especially acrylic (Perspex), a sharp bit is essential to reduce friction and heat which will tend to melt the plastic and coat/clog the bit, further increasing friction. When drilling heavy or fixed objects, this is unnecessary. Otherwise if the bit jams while drilling, the workpiece can spin around uncontrollably. Make sure they are held in a vice or clamped securely with quick release or G clamps. Don't hold small workpieces while drilling.Wood or masonry bits don't need to be lubricated. Diamond drill bits can be lubricated with water. Kerosene or soapy water is suitable for lubricating softer metals such as aluminum or brass which have a more "sticky" swarf (the waste material which spirals out of the drill hole). Alternatively If using a power drill, keep a bottle capful of light oil nearby, and dip the tip of the drill bit every so often into it to cool it. If you're using a pillar drill, you can use an oil can or some form of "squirty" bottle to spread oil into the hole. Lubricate the bit and workpiece with light machine oil if drilling steel.This is essential with flat wood bits which don't have flutes (the helical slots on the sides). This prevents the power drill from being overloaded and the bit overheating. When drilling, back out of the hole every so often to remove material. It's practically essential to do this on smooth surfaces such as steel. Use a centre punch to make a dent in the material being drilled.In general, the larger the diameter of the drill bit, the lower the speed and vice versa The advantage of an electronic calipers is that the display can be read directly, switched between imperial (inch) and metric and the jaws can be zeroed to cope with any drift or wear. Alternatively an electronic calipers displays the result on an LCD scale which can be read directly. You can buy a purely mechanical vernier calipers, which has a vernier scale. Resolution is normally about 0.05 mm or 2 thousandths of an inch. You can also use it for measuring thickness of materials, internal hole diameters and general purpose measuring. You can roughly measure the diameter of a bit with a tape or ruler, but a vernier or electronic calipers is the proper tool for the job. So you can end up with a lot of unknown size bits in your collection. Unfortunately manufacturers insist on placing the marking near the end of the shank, so it can get worn off over time if a round profile shank slips in a chuck. Normally the size is stamped or engraved on the shank of a bit. The same goes for cutting this plastic with a jigsaw, use a slow speed. It's not such a big deal when drilling through thin plastic, but I've found that when drilling through thicker sheets and specifically acrylic (commonly known by the brand names "Plexiglass" or "Perspex"), this can be a problem. As shavings cool and get stuck in the flutes, or coat the bit, the problem gets worse and the bit can get stuck. If you drill fast, friction can rapidly cause plastic to melt, clogging the tip and flutes of the drill with melted shavings, especially if the bit is blunt. Some hole saws are only designed for drilling wood or plastic while other versions are made from HSS steel and suitable for drilling iron, steel and other metals in addition to wood. This has small teeth like a handsaw and the "blade" is in the form of a cylinder. Instead, drilling large holes can be accomplished with a hole saw. Drilling very large holes greater than 1 1/2 inches with a standard bit is impractical as you would need a drill with a huge amount of power and torque to overcome friction in order to drill through timber.
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