A rotary drill is any mechanical device that performs its hole-making function by spinning. The most primitive types of rotary drill date from 3000 B.C. in the form of hand-operated wood and dirt augers. Today, highly advanced rotary drills are used, on a small scale, in drilling into teeth in dentistry, and on a large scale, in deep earth mineral and gas exploration. In modern construction, a rotary drill can be affixed with various drill bits to create various-sized holes in wood and metal through which bolts can be placed.
When affixed with a bit, a rotary drill uses centrifugal force to simultaneously dig into an object and lift debris out of the hole. The spinning action makes the drill different from other related tools. An awl, for example, punches through an object, while a hammer drill combines the two actions of drilling and punching.
A rotary drill uses bits to perform the drilling; a bit is a cylindrical object with a pointed end for cutting. Bits are engineered with grooves running on their sides that ease the boring action by directing debris back up the bit and out of the hole. Some bits are also designed with inner channels allowing water or other lubricants to run into the hole, reducing heat and facilitating the drilling action. Bits come in many sizes and are made out of various materials for use in different projects. For instance, steel bits are often used for wood working, while titanium bits with diamond points may be preferred for masonry work.
As a construction tool, a rotary drill can be stationary, in the form of a drill press. This allows the operator a large amount of control when drilling through a piece of lumber or a sheet of metal. Rotary drills can also be mobile, in the form of a hand-held drill gun. These are most commonly powered by electricity delivered through an electrical cord and allow for drilling into already set construction material such as brick, concrete, or wood frames.
Similar to drill guns are cordless rotary drills. The cordless rotary drill is a hand-held device used in construction and household repair that runs on batteries as opposed to having a cord plugged into an electrical outlet. These are generally not as powerful as corded drill guns, but are generally lighter, offer an ease of movement and are not limited by power supply availability.