Hammer

A hammer is a

The modern hammer head is typically made of steel which has been heat treated for hardness, and the handle (also known as a haft or helve) is typically made of wood or plastic.

Ubiquitous in

For hand hammers, the grip of the shaft is an important consideration. Many forms of hammering by hand are heavy work, and perspiration can lead to slippage from the hand, turning a hammer into a dangerous or destructive uncontrolled projectile. Steel is highly elastic and transmits shock and vibration; steel is also a good conductor of heat, making it unsuitable for contact with bare skin in frigid conditions. Modern hammers with steel shafts are almost invariably clad with a synthetic polymer to improve grip, dampen vibration, and to provide thermal insulation. A suitably contoured handle is also an important aid in providing a secure grip during heavy use. Traditional wooden handles were reasonably good in all regards, but lack strength and durability compared to steel, and there are safety issues with wooden handles if the head becomes loose on the shaft.

The high elasticity of the steel head is important in energy transfer, especially when used in conjunction with an equally elastic anvil.

In terms of

The use of simple hammers dates to around 3.3 million years ago according to the 2012 find made by Sonia Harmand and Jason Lewis of Stony Brook University, who while excavating a site near Kenya's Lake Turkana discovered a very large deposit of various shaped stones including those used to strike wood, bone, or other stones to break them apart and shape them.^[5][6] The first hammers were made without handles. Stones attached to sticks with strips of leather or animal sinew were being used as hammers with handles by about 30,000 BCE during the middle of the Paleolithic Stone Age. The addition of a handle gave the user better control and less accidents. The hammer became the primary tool used for building, food, and protection.^[7]

The hammer's archaeological record shows that it may be the oldest tool for which definite evidence exists.^[5][6]

• 
  A stone hammer found in

  North American Archaic period
• 
  Stone tapping hammer
• 
  Perforated hammer head of stone
• 
  Ancient Greek bronze sacrificial hammer, 7th century BCE, from Dodona
• 
  16th-century claw hammer; detail from Dürer's Melencolia I (c. 1514)

Construction and materials

A traditional hand-held hammer consists of a separate head and a handle, which can be fastened together by means of a special

Some hammers are one-piece designs made mostly of a single material. A one-piece metallic hammer may optionally have its handle coated or wrapped in a resilient material such as rubber for improved grip and to reduce user fatigue.^[8]

The hammer head may be surfaced with a variety of materials including brass, bronze, wood, plastic, rubber, or leather. Some hammers have interchangeable striking surfaces, which can be selected as needed or replaced when worn out.

Designs and variations

A large hammer-like tool is a maul (sometimes called a "beetle"), a wood- or rubber-headed hammer is a mallet, and a hammer-like tool with a cutting blade is usually called a hatchet. The essential part of a hammer is the head, a compact solid mass that is able to deliver a blow to the intended target without itself deforming. The impacting surface of the tool is usually flat or slightly rounded; the opposite end of the impacting mass may have a ball shape, as in the ball-peen hammer. Some upholstery hammers have a magnetized face, to pick up tacks. In the hatchet, the flat hammer head may be secondary to the cutting edge of the tool.

The impact between steel hammer heads and the objects being hit can create

• Ball-peen hammer,^[9] or mechanic's hammer
• Boiler scaling hammer^[9]
• Brass hammer, also known as non-sparking hammer or spark-proof hammer and used mainly in flammable areas like oil fields
• Bricklayer's hammer
• Carpenter's hammer (used for nailing), such as the framing hammer and the claw hammer, and pinhammers (ball-peen and cross-peen types)^[9]
• Cow hammer – sometimes used for
  animal welfare objections^[10]
• Cross-peen hammer,[9] having one round face and one wedge-peen face.
• lead shot
  or pellets
• Demolition hammer
• Drilling hammer – a short handled sledgehammer originally used for drilling in rock with a chisel. The name usually refers to a hammer with a 2-to-4-pound (0.91 to 1.81 kg) head and a 10-inch (250 mm) handle, also called a "single-jack" hammer because it was used by one person drilling, holding the chisel in one hand and the hammer in the other.^[11]
  In modern usage, the term is mostly interchangeable with "engineer's hammer", although it can indicate a version with a slightly shorter handle.
• Engineer's hammer, a short-handled hammer, was originally an essential components of a
  railroad engineer's toolkit for working on steam locomotives.^[12]
  Typical weight is 2–4 lbs (0.9–1.8 kg) with a 12–14-inch (30–35 cm) handle. Originally these were often cross-peen hammers, with one round face and one wedge-peen face, but in modern usage the term primarily refers to hammers with two round faces.
• Gavel, used by judges and presiding authorities to draw attention
• Geologist's hammer or rock pick
• Joiner's hammer, or Warrington hammer^[9]
• Knife-edged hammer, its properties developed to aid a hammerer in the act of slicing whilst bludgeoning
• Lathe hammer (also known as a lath hammer, lathing hammer, or lathing hatchet), a tool used for cutting and nailing wood lath, which has a small hatchet blade on one side (with a small, lateral nick for pulling nails) and a hammer head on the other^[13]
• Lump hammer
  , or club hammer
• Mallets, including versions made with hard rubber or rolled sheets of rawhide
• Railway track keying hammer^[9]
• Magnetic double-head hammer
• Magnetic tack hammer
• Rock climbing hammer
• Rounding hammer, Blacksmith or farrier hammer. Round face generally for moving or drawing metal and flat for "planishing" or smoothing out the surface marks.
• Shingler's hammer
• Sledgehammer
• Soft-faced hammer
• Spiking hammer
• Splitting maul
• Strike Tack hammer
• Stonemason's hammer
• Tinner's hammer
• Upholstery hammer
• Welder's chipping hammer^[9]

Mechanically powered

Mechanically powered hammers often look quite different from the hand tools, but nevertheless, most of them work on the same principle. They include:

• Hammer drill, that combines a jackhammer-like mechanism with a drill
• High Frequency Impact Treatment
  hammer – for after-treatment of weld transitions
• Jackhammer
• Steam hammer
• Trip hammer
• Nail gun
• Staple gun

Associated tools

• Anvil
• Chisel
• Pipe drift (Blacksmithing – spreading a punched hole to proper size and/or shape)
• Star drill
• Punch
• Woodsplitting maul – can be hit with a sledgehammer for splitting wood.
• Woodsplitting wedge
  – hit with a sledgehammer for splitting wood.

Physics

As a force amplifier

A hammer is a simple

In the swing that precedes each blow, the hammer head stores a certain amount of kinetic energy—equal to the length D of the swing times the force f produced by the muscles of the arm and by gravity. When the hammer strikes, the head is stopped by an opposite force coming from the target, equal and opposite to the force applied by the head to the target. If the target is a hard and heavy object, or if it is resting on some sort of anvil, the head can travel only a very short distance d before stopping. Since the stopping force F times that distance must be equal to the head's kinetic energy, it follows that F is much greater than the original driving force f—roughly, by a factor D/d. In this way, great strength is not needed to produce a force strong enough to bend steel, or crack the hardest stone.

Effect of the head's mass

The amount of energy delivered to the target by the hammer-blow is equivalent to one half the mass of the head times the square of the head's speed at the time of impact ${\displaystyle (E={mv^{2} \over 2})}$. While the energy delivered to the target increases linearly with mass, it increases quadratically with the

Most designs are a compromise between practicality and energy efficiency. With too long a handle, the hammer is inefficient because it delivers force to the wrong place, off-target. With too short a handle, the hammer is inefficient because it does not deliver enough force, requiring more blows to complete a given task. Modifications have also been made with respect to the effect of the hammer on the user. Handles made of shock-absorbing materials or varying angles attempt to make it easier for the user to continue to wield this age-old device, even as nail guns and other powered drivers encroach on its traditional field of use.

As hammers must be used in many circumstances, where the position of the person using them cannot be taken for granted, trade-offs are made for the sake of practicality. In areas where one has plenty of room, a long handle with a heavy head (like a sledgehammer) can deliver the maximum amount of energy to the target. It is not practical to use such a large hammer for all tasks, however, and thus the overall design has been modified repeatedly to achieve the optimum utility in a wide variety of situations.

Effect of gravity

Gravity exerts a force on the hammer head. If hammering downwards, gravity increases the acceleration during the hammer stroke and increases the energy delivered with each blow. If hammering upwards, gravity reduces the acceleration during the hammer stroke and therefore reduces the energy delivered with each blow. Some hammering methods, such as traditional mechanical pile drivers, rely entirely on gravity for acceleration on the down stroke.

Ergonomics and injury risks

A hammer may cause significant injury if it strikes the body. Both manual and powered hammers can cause

War hammers

A war hammer is a

The hammer, being one of the most used tools by

In mythology, the gods Thor (Norse) and Sucellus (Celtic and Gallo-Roman), and the hero Hercules (Greek), all had hammers that appear in their lore and carried different meanings. Thor, the god of thunder and lightning, wields a hammer named Mjölnir. Many artifacts of decorative hammers have been found, leading modern practitioners of this religion to often wear reproductions as a sign of their faith.

In American folklore, the hammer of John Henry represents the strength and endurance of a man.

A political party in Singapore, Workers' Party of Singapore, based their logo on a hammer to symbolize the party's civic nationalism and social democracy ideology.

A variant, well-known symbol with a hammer in it is the hammer and sickle, which was the symbol of the former Soviet Union and is strongly linked to communism and early socialism. The hammer in this symbol represents the industrial working class (and the sickle represents the agricultural working class). The hammer is used in some coats of arms in former socialist countries like East Germany. Similarly, the Hammer and Sword symbolizes Strasserism, a strand of Nazism seeking to appeal to the working class. Another variant of the symbol was used for the North Korean party, Workers' Party of Korea, incorporated with an ink brush on the middle, which symbolizes both Juche and Songun ideologies.

In

The gavel, a small wooden mallet, is used to symbolize a mandate to preside over a meeting or judicial proceeding, and a graphic image of one is used as a symbol of legislative or judicial decision-making authority.

The hammer in the song "If I Had a Hammer" represents a relentless message of justice broadcast across the land. The song became a symbol of the civil rights movement.

Image gallery

• 
  Ball-peen hammer
• 
  Bush hammer
• 
  Claw hammer
• 
  Cross-peen hammer
• 
  Dog-head hammer (blacksmithing)
• 
  Framing hammer
• 
  Geologist's hammer
• 
  HiFIT-hammer for aftertreatment of weld transitions
• 
  Long cross-face hammer (blacksmithing)
• 
  Post maul
• 
  Rock climbing hammer
• 
  Rubber mallet
• 
  Sledgehammers
• 
  Straight pane sledgehammer
• 
  Twist hammer (blacksmithing)
• 
  Upholstery hammer
• 
  Wooden mallet

See also

• Hammer Museum (Haines, Alaska)
• Mjölnir

References

External links

Wikimedia Commons has media related to Hammers.

Look up hammer in Wiktionary, the free dictionary.

• Types of Hammers (images and descriptions)
• "Choosing a Hammer". Popular Science, June 1960, pp. 164–167.