Drill

Hand-operated types are dramatically decreasing in popularity and cordless battery-powered ones proliferating due to increased efficiency and ease of use.

Drills are commonly used in woodworking, metalworking, construction, machine tool fabrication, and utility projects.

Archaeologists discovered a Neolithic grave yard in Mehrgarh, Pakistan, dating from the time of the Harappans, around 7,500–9,000 years ago, containing nine adult bodies with a total of eleven teeth that had been drilled.

[5] The usage of bow-drills was widely spread through Europe, Africa, Asia, and North America, during ancient times and is still used today.

Over the years many slight variations of bow and strap drills have developed for the various uses of either boring through materials or lighting fires.

[7] The hollow-borer tip, first used around the 13th century, consisted of a stick with a tubular shaped piece of metal on the end, such as copper.

This completely separates the inner stone or wood from the rest, allowing the drill to pulverize less material to create a similarly sized hole.

Archimedes' screw, present in drills to remove perforation dirt from the hole, was invented in Hellenistic Egypt around 300 BCE.

[6] In 1835 Isaac Singer is reported to have built a steam powered churn drill based on the method the Chinese of a rod tipped with a bit.

[14] Also worth briefly discussing are the early drill presses; they were machine tools that derived from bow-drills but were powered by windmills or water wheels.

It is credited to mining engineers Arthur James Arnot and William Blanch Brain of Melbourne, Australia who patented the electric drill in 1889.

Over the last century the electric drill has been created in a variety of types and multiple sizes for an assortment of specific uses.

They include: Drills powered by electricity (or more rarely, compressed air) are the most common tools in woodworking and machining shops.

NiCd disadvantages are limited life, self-discharging, environment problems upon disposal, and eventually internally short circuiting due to dendrite growth.

Lithium-ion batteries are becoming more common because of their short charging time, longer life, absence of memory effect, and low weight.

Electric impact drills are most often found cordless and are widely used in construction, automobile repair, and fabrication.

Impact drivers can also be used to bore holes like a standard pistol grip drill, but this requires a special bit that will lock into the hexagonal collet.

The operator experiences considerable vibration, and the cams are generally made from hardened steel to avoid them wearing out quickly.

A typical application for a hammer drill is installing electrical boxes, conduit straps or shelves in concrete.

Major components include a base, column (or pillar), adjustable table, spindle, chuck, and drill head, usually driven by an electric motor.

The head typically has a set of three handles radiating from a central hub that are turned to move the spindle and chuck vertically.

Medium-duty drill presses such as those used in machine shop (tool room) applications are equipped with a continuously variable transmission.

This can be unsafe in some cases, as the chuck arbor, which may be retained in the spindle solely by the friction of a taper fit, may dislodge during operation if the side loads are too high.

Levers attached to one side of the head are used to select different gear ratios to change the spindle speed, usually in conjunction with a two- or three-speed motor (this varies with the material).

Most machines of this type are designed to be operated on three-phase electric power and are generally of more rugged construction than equivalently sized belt-driven units.

A clutch mechanism drives the tap into the part under power and then backs it out of the threaded hole once the proper depth is reached.

This feature saves considerable time because it is much faster to reposition the machine's head than it is to unclamp, move, and then re-clamp the workpiece to the table.

A vise may be used with a radial arm drill press, but more often the workpiece is secured directly to the table or base, or is held in a fixture.

There are various types depending on their operations and specializations, like magnetic drilling / tapping machines, cordless, pneumatic, compact horizontal, automatic feed, cross table base etc.

They combine a drill press (belt driven) with the X/Y coordinate abilities of the milling machine's table and a locking collet that ensures that the cutting tool will not fall from the spindle when lateral forces are experienced against the bit.