Long drill bits, often called extension bits, are drill bits that have been attached to longer than standard shafts. Tools fitted with this kind of bit allow the user to reach into tighter areas. Such bits are generally available in the same types as standard bits. Commonly used long drill bit types include screwdriver bits, tile bits, twist bits, masonry bits and flat bits. Hole saws are also often used with an extension bit.
Screwdriver bits and twist bits are the two types of long drill bits generally used by homeowners and casual users. A screwdriver bit, as the name implies, is used to sink screws, bolts and other threaded fasteners. The bit can be made to fit a number of different head types, including standard or slotted, Phillips, and both hex-hole and hex-head.
A twist bit is the type of bit most commonly used to drill a small hole in drywall, wood, plastic or metal prior to inserting a fastener. This type of long drill bit comes in a variety of sizes that create different sizes of holes. They are also available in different materials to accommodate different substrates.
Specialty bits also are available for drilling into specific types of substrates. Masonry long drill bits, for instance, would be used to drill into stone or brick. Likewise, a tile bit would be used to drill into ceramic, porcelain or terra cotta tile. These bits are specially formed and tempered to reduce the likelihood of chipping the substrate during use.
Flat bits and hole saws are used to drill large holes. A flat bit has a point in the middle and flat edges. It is used to create a flat-bottomed hole, often so that the head of a screw or other fastener can be sunk level with the surface. Such bits are most often used on wood.
Hole saws are a special type of long drill bit. A circular piece of metal with teeth surrounds the central drill tip. When applied to the substrate, this cuts a round hole. Such bits are often used to create holes in drywall and concrete board so that wiring or pipes can be fed through the holes.
In most cases, long drill bits are universal, meaning they can be used with any standard drill. Some bits may, however, work better with certain models than with others. Such bits can be purchased online, at hardware stores and in the hardware or tool departments of many home improvement stores. Bits are routinely sold individually and as kits.