Hammer

A hammer is a tool consisting of a weighted 'head' fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nails into wood, to shape metal (as with a forge), or to crush rock. Hammers are used for a wide range of driving, shaping, and breaking applications. The modern hammer head is typically made of steel which has been heat treated for hardness, and the handle (also called a haft or helve) is typically made of wood or plastic. The claw hammer has a 'claw' to pull nails out of wood, and is commonly found in an inventory of household tools in North America. Other types of hammer vary in shape, size, and structure, depending on their purposes. Hammers used in many trades include sledgehammers, mallets, and ball-peen hammers. Although most hammers are hand tools, powered hammers, such as steam hammers and trip hammers, are used to deliver forces beyond the capacity of the human arm. There are over 40 different types of hammers that have many different types of uses. 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. 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 number one tool. Used for building, food and protection. The hammer's archaeological record shows that it may be the oldest tool for which definite evidence exists of its early existence. A traditional hand-held hammer consists of a separate head and a handle, which can be fastened together by means of a special wedge made for the purpose, or by glue, or both. This two-piece design is often used to combine a dense metallic striking head with a non-metallic mechanical-shock-absorbing handle (to reduce user fatigue from repeated strikes). If wood is used for the handle, it is often hickory or ash, which are tough and long-lasting materials that can dissipate shock waves from the hammer head. Rigid fiberglass resin may be used for the handle; this material does not absorb water or decay but does not dissipate shock as well as wood.