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Acircular saw or abuzz saw, is a power-saw using a toothed orabrasivedisc orblade to cut different materials using a rotary motion spinning around anarbor. Ahole saw andring saw also use a rotary motion but are different from a circular saw.Circular saw may also be loosely used for the blade itself. Circular saws were invented in the late 18th century and were in common use insawmills in the United States by the middle of the 19th century.
A circular saw is atool for cutting many materials such aswood,masonry,plastic, ormetal and may be hand-held or mounted to a machine. In woodworking the termcircular saw refers specifically to the hand-held type and thetable saw andchop saw are other common forms of circular saws.Skilsaw andSkil saw have become generic trademarks for conventional hand-held circular saws in the United States. Circular saw blades are specially designed for each particular material they are intended to cut and in cutting wood are specifically designed for makingrip-cuts, cross-cuts, or a combination of both. Circular saws are commonly powered by electricity, but may be powered by a gasoline engine or ahydraulic motor which allows it to be fastened to heavy equipment, eliminating the need for a separate energy source.[1]
There is evidence for the prehistorical use of circular saws by people ofIndus Valley Civilization during theBronze Age. The same was excavated from the archeological site ofLothal,Gujarat.[2][3]
The modern-day circular saw was invented around the end of the 18th century as arip-saw to convert logs intolumber in sawmills and various claims have been made as to who invented it. Before the design was invented, logs were sawn by hand using apit saw or using powered saws in a sawmill using anup-and-down saw with areciprocating motion. The rotary nature of the circular saw requires more power to operate but cuts faster because the teeth are in constant motion. The sound of the circular saw is different from the sound of an up-and-down saw and earned it the nicknamebuzz-saw.
Sawmills first used smaller diameter circular saws to resaw dimension lumber such aslath andwall studs and foredging boards. As the technology advanced large diameter saw blades began to be used for thehead saws and to cutclapboards.
Claims to the invention of the circular saw include:
Typically, the material to be cut is securely clamped or held in avise, and the saw is advanced slowly across it. In variants such as thetable saw, the saw is fixed and the material to be cut is slowly moved into the saw blade. As each tooth in the blade strikes the material, it makes a small chip.[15] The teeth guide the chip out of the workpiece, preventing it from binding the blade.
In addition to hand-held circular saws (see below), different saws that use circular saw blades include:
Originally, circular saws in mills had smaller blades and were used to resaw lumber after it passed through an "up and down" (muley or sash) saw leaving both vertical and circular saw marks on different sides of the same piece. These saws made it more efficient to cut small pieces such as lath.After 1813 or 1822 saw mills use large circular saws, up to 3 metres (9.8 ft) in diameter. Large saws demand more power than up-and-down saws and did not become practical for sawing timbers until they were powered by steam engines. They are either left or right-handed, depending on which side of the blade the plank falls away from.Benching determines which hand the saw is. Saws of this size typically have ashear pin hole, off axis, that breaks if the saw is overloaded and allows the saw to spin free. The most common version is theITCO (insert tooth cut-off) which has replaceable teeth. Sawmill blades are also used as an alternative to a radial arm saw.
Cordwood saws, also called buzz saws in some locales, use blade of a similar size to sawmills. Where a sawmill rips (cuts with the grain) a cordwood saw crosscuts (cuts across the grain). Cordwood saws can have a blade from 20 inches (510 mm) to more than 36 inches (910 mm) diameter depending on the power source and intended purpose. Cordwood saws are used to cut logs and slabs (sawmill waste) intofirewood. Thecubic meter andcord (unit) are common measurements of standing timber (by estimation) or rough logs. "Cordwood" means unsplit logs 4 feet (1.2 m) long. In the nineteenth and early twentieth centuries, farmers would supply householders in town with cordwood, which would then be re-sawn and split to a length and circumference suitable for woodburning heaters and ranges. Almost all these devices were designed to accept 16-inch (410 mm) sticks, conveniently a piece of cordwood cut into three equal lengths. Once a piece of cordwood had been re-sawn to three 16-inch pieces, it could easily be split to stovewood size with an ax.
Most cordwood saws consist of a frame, blade, mandrel, cradle, and power source. The cradle is a tilting or sliding guide that holds logs during the cutting process. Certain cordwood saws are run from a belt from a farm tractor power takeoff pulley. Others, mounted on a tractor's three-point hitch, connect to the rear power takeoff shaft. Self-powered models are equipped with small gasoline engines or even large electric motors as power sources. The mandrel is a shaft and set of bearings that support and transfer power to the blade. The frame is a structure that supports the cradle and blade at a convenient working height.
Cordwood saws were once very popular in rural America. They were used to cut smaller wood into firewood in an era when hand powered saws were the only other option. Logs too large for a cordwood saw were still cut by hand.Chainsaws[16] have largely replaced cordwood saws for firewood preparation today. Still, some commercial firewood processors and others use cordwood saws to save wear and tear on their chainsaws. Most people consider cordwood saws unsafe and outdated technology.
In woodworking the term circular saw is most commonly used to refer to a hand-held,electric circular saw designed for cutting wood, but may be used for cutting other materials with different blades. Circular saws can be either left or right-handed, depending on the side of the blade where the motor sits. A left-handed saw is typically easier to use if held in the right hand, and contrariwise for the right-handed saw, because the user does not need to lean across the saw to see the cutting line.
Blades for cutting wood are almost universallytungsten carbide tipped (TCT), but high-speed steel (HSS) blades are also available. The saw base can be adjusted for depth of cut and can tilt up to 45° and sometimes 50° in relation to the blade. Adjusting the depth of cut helps minimize kickback. Different diameter blades are matched to each saw and are available ranging from 14 to 61 centimetres (5.5–24.0 in).
Saws can have two different types of linkages between the motor and the blade. In the type known colloquially as asidewinder, the blade is mounted directly on themotor'sdriveshaft. In aworm-drive saw, the blade is driven by a perpendicularly mounted motor usingworm gears, which give higher torque.
The worm-drive portable circular saw was invented in 1923 by Edmond Michel. In 1924 Michel formed a partnership with Joseph Sullivan, and together they started theMichel Electric Handsaw Company, with the sole purpose of manufacturing and marketing the saw invented by Michel. The company later renamed itselfSkilsaw Inc. Portable circular saws are often still called Skilsaws or Skil saws. Its successor is still sold by Skil as the model 77. To get around the Skilsaw patents,Art Emmons ofPorter-Cable invented the direct-drive sidewinder saw in 1928. Recently[when?] smallercordless circular saws withrechargeable batteries have become popular.
Cold saw machines are circular saws that are used in many metal cutting operations. The saw blades used are quite large in diameter and operate at low rotational speeds, and linear feeds. There are three common types of blades used in circular saws; solid-tooth, segmental tooth, and the carbide inserted-tooth. The circular saw is typically fed into the workpiece horizontally, and as the saw advances into the material, it severs the material by producing narrow slots. The material is usually held in place during the cutting operation by means of a vise. The chips produced by cutting are carried away from the material by both the teeth of the blade as well as the coolant or other cutting fluid used.
The rotary motion of a circular saw lends itself to cutting hard materials like concrete, asphalt, metal, tile, brick, and stone with anabrasive saw such as atile saw.Diamond blades andcut off wheels are commonly used in these applications.
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