A machine drill is generally one of two things. The first is a machine-operated drill, like a drill press. These drills have a motor turning the bit and the human operator, if it has one, simply keeps it steady. The other common type of machine drill is a drill that machines parts—machining is the process of selectively removing metal to form a part into a desired shape and configuration. While a machining tool may have a human operator for the entire machine, the drilling phase is generally part of a larger process and doesn’t receive direct oversight.
Drills are one of the oldest human-made complex tools. They first came into use about 5,000 years ago. These early drills were human-powered and nearly identical in basic design to modern human-powered drills. The first major improvement to the design was the bow drill, a drill that had a bow wrapped around it that aided its spinning; this was essentially the first indirectly powered drill. The first motorized drills in the mid-1800s were simply motorized bow drills.
Eventually, these motorized bow drills simplified into two major forms, the drill press and the hand drill. The hand drill is likely the most basic machine drill form available. It is simply a motor connected to a drill shaft with a trigger to turn the motor on and off. This type of drill, due to its simple construction and inexpensive components, is both cheap and widely available. The hand drill is the only common machine drill that may be moved to where the hole needs to be; the others require the drilled object be brought to them.
The drill press is a much more advanced form of machine drill. The drill component works very similarly to a hand drill; it is just a motor connected to a drill shaft. This component is mounted to a shaft so it is held in a fixed position. Generally, the drill is able to slide up and down on a single axis. The drill, at the extreme of one of its ends, will intersect a plate that is also held in a fixed position. Anything that needs drilling is placed on this plate and moved to accommodate the movements of the drill.
A machine drill used as part of a machining tool is the most complicated version. There are a wide range of drilling machine tools, and they operate very differently. The most basic form works like a drill press, often as part of an automated assembly line. The more common type comes as part of a larger machining tool, where a drill is one of the tools available to a single machine. Some of these machines have multiple tools available at different points in the same machine, while others have a single location and a rotating tool set.