Carpentry is a skilled trade and a craft in which the primary work performed is the cutting, shaping and installation of building materials during the construction of buildings , ships , timber bridges , concrete formwork , etc. Carpenters traditionally worked with natural wood and did rougher work such as framing, but today many other materials are also used and sometimes the finer trades of cabinetmaking and furniture building are considered carpentry. In the United States, 98.5% of carpenters are male, and it was the fourth most male-dominated occupation in the country in 1999. In 2006 in the United States, there were about 1.5 million carpentry positions. Carpenters are usually the first tradesmen on a job and the last to leave. Carpenters normally framed post-and-beam buildings until the end of the 19th century; now this old-fashioned carpentry is called timber framing . Carpenters learn this trade by being employed through an apprenticeship training—normally four years—and qualify by successfully completing that country's competence test in places such as the United Kingdom , the United States , Canada , Switzerland , Australia and South Africa . It is also common that the skill can be learned by gaining work experience other than a formal training program, which may be the case in many places.
96-516: Carpentry covers various services, such as furniture design and construction, door and window installation or repair, flooring installation, trim and molding installation, custom woodworking, stair construction, structural framing, wood structure and furniture repair, and restoration. The word "carpenter" is the English rendering of the Old French word carpentier (later, charpentier ) which
192-403: A buzz saw , is a power- saw using a toothed or abrasive disc or blade to cut different materials using a rotary motion spinning around an arbor . A hole saw and ring saw also use a rotary motion but are different from a circular saw. Circular saws may also be loosely used for the blade itself. Circular saws were invented in the late 18th century and were in common use in sawmills in
288-428: A construction material , for making tools and weapons , furniture and paper . More recently it emerged as a feedstock for the production of purified cellulose and its derivatives, such as cellophane and cellulose acetate . As of 2020, the growing stock of forests worldwide was about 557 billion cubic meters. As an abundant, carbon-neutral renewable resource, woody materials have been of intense interest as
384-879: A pit saw or sawmill called lumber (American English) or timber (British English). Today natural and engineered lumber and many other building materials carpenters may use are typically prepared by others and delivered to the job site. In 2013 the carpenters union in America used the term carpenter for a catch-all position. Tasks performed by union carpenters include installing "...flooring, windows, doors, interior trim, cabinetry, solid surface, roofing, framing, siding, flooring, insulation, ...acoustical ceilings, computer-access flooring, metal framing, wall partitions, office furniture systems, and both custom or factory-produced materials, ...trim and molding,... ceiling treatments, ... exposed columns and beams, displays, mantels, staircases...metal studs, metal lath, and drywall..." Carpentry
480-506: A carpenter begins as an apprentice , then becomes a journeyman , and with enough experience and competency can eventually attain the status of a master carpenter. Today pre-apprenticeship training may be gained through non-union vocational programs such as high school shop classes and community colleges. Informally a laborer may simply work alongside carpenters for years learning skills by observation and peripheral assistance. While such an individual may obtain journeyperson status by paying
576-411: A carpenter..." although the "...work of a carpenter and joiner are often combined." Joiner is less common than the terms finish carpenter or cabinetmaker . The terms housewright and barnwright were used historically and are now occasionally used by carpenters who work using traditional methods and materials . Someone who builds custom concrete formwork is a form carpenter . Along with stone, wood
672-427: A closed forest, and in the manufacture of articles where strength is an important consideration such "second-growth" hardwood material is preferred. This is particularly the case in the choice of hickory for handles and spokes . Here not only strength, but toughness and resilience are important. The results of a series of tests on hickory by the U.S. Forest Service show that: Circular saw A circular saw or
768-496: A college or other institution. Depending on the number of hours of instruction an apprentice receives, they can earn a Certificate of Proficiency, making them a journeyperson, or a Certificate of Qualification, which allows them to practice a more limited amount of carpentry. Canadian carpenters also have the option of acquiring an additional Interprovincial Red Seal that allows them to practice anywhere in Canada. The Red Seal requires
864-416: A finished building. An easy way to envisage this is that first fix work is all that is done before plastering takes place. The second fix is done after plastering takes place. Second fix work, the installation of items such as skirting boards, architraves, doors, and windows are generally regarded as carpentry, however, the off-site manufacture and pre-finishing of the items is regarded as joinery . Carpentry
960-540: A formal apprenticeship program for traditional timber framing . Training is also available in groups like the Kim Bồng woodworking village in Vietnam where apprentices live and work to learn woodworking and carpentry skills. In Canada, each province sets its own standards for apprenticeship. The average length of time is four years and includes a minimum number of hours of both on-the-job training and technical instruction at
1056-431: 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
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#17327733326641152-401: A heavy piece of pine is compared with a lightweight piece it will be seen at once that the heavier one contains a larger proportion of latewood than the other, and is therefore showing more clearly demarcated growth rings. In white pines there is not much contrast between the different parts of the ring, and as a result the wood is very uniform in texture and is easy to work. In hard pines , on
1248-608: A journeyperson carpenter in the United States may be obtained in a number of ways. Formal training is acquired in a four-year apprenticeship program administered by the United Brotherhood of Carpenters and Joiners of America, in which journeyperson status is obtained after successful completion of twelve weeks of pre-apprenticeship training, followed by four years of on-the-job field training working alongside journeyperson carpenters. The Timber Framers Guild also has
1344-545: A language that they can understand." Examples of how to prevent falls includes placing railings and toe-boards at any floor opening which cannot be well covered and elevated platforms and safety harness and lines, safety nets, stair railings, and handrails. Safety is not just about the workers on the job site. Carpenters' work needs to meet the requirements in the Life Safety Code such as in stair building and building codes to promote long-term quality and safety for
1440-405: A large log the sapwood, because of the time in the life of the tree when it was grown, may be inferior in hardness , strength , and toughness to equally sound heartwood from the same log. In a smaller tree, the reverse may be true. In species which show a distinct difference between heartwood and sapwood the natural color of heartwood is usually darker than that of the sapwood, and very frequently
1536-400: A log is on the outside, it is more or less knotty near the middle. Consequently, the sapwood of an old tree, and particularly of a forest-grown tree, will be freer from knots than the inner heartwood. Since in most uses of wood, knots are defects that weaken the timber and interfere with its ease of working and other properties, it follows that a given piece of sapwood, because of its position in
1632-481: A pretty definite relation between the rate of growth of timber and its properties. This may be briefly summed up in the general statement that the more rapid the growth or the wider the rings of growth, the heavier, harder, stronger, and stiffer the wood. This, it must be remembered, applies only to ring-porous woods such as oak, ash, hickory, and others of the same group, and is, of course, subject to some exceptions and limitations. In ring-porous woods of good growth, it
1728-491: 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) into firewood . The cubic meter and Cord (unit) are common measurements of standing timber (by estimation) or rough logs. "Cordwood" means unsplit logs 4 feet (1.2 m) long. In
1824-636: A source of renewable energy. In 2008, approximately 3.97 billion cubic meters of wood were harvested. Dominant uses were for furniture and building construction. Wood is scientifically studied and researched through the discipline of wood science , which was initiated since the beginning of the 20th century. A 2011 discovery in the Canadian province of New Brunswick yielded the earliest known plants to have grown wood, approximately 395 to 400 million years ago . Wood can be dated by carbon dating and in some species by dendrochronology to determine when
1920-465: A source of weakness. In diffuse-porous woods the pores are evenly sized so that the water conducting capability is scattered throughout the growth ring instead of being collected in a band or row. Examples of this kind of wood are alder , basswood , birch , buckeye, maple, willow , and the Populus species such as aspen, cottonwood and poplar. Some species, such as walnut and cherry , are on
2016-564: A tree is first formed as sapwood. The more leaves a tree bears and the more vigorous its growth, the larger the volume of sapwood required. Hence trees making rapid growth in the open have thicker sapwood for their size than trees of the same species growing in dense forests. Sometimes trees (of species that do form heartwood) grown in the open may become of considerable size, 30 cm (12 in) or more in diameter, before any heartwood begins to form, for example, in second growth hickory , or open-grown pines . No definite relation exists between
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#17327733326642112-423: A type of imperfection known as a knot. The dead branch may not be attached to the trunk wood except at its base and can drop out after the tree has been sawn into boards. Knots affect the technical properties of the wood, usually reducing tension strength, but may be exploited for visual effect. In a longitudinally sawn plank, a knot will appear as a roughly circular "solid" (usually darker) piece of wood around which
2208-492: A wooden object was created. People have used wood for thousands of years for many purposes, including as a fuel or as a construction material for making houses , tools , weapons , furniture , packaging , artworks , and paper . Known constructions using wood date back ten thousand years. Buildings like the longhouses in Neolithic Europe were made primarily of wood. Recent use of wood has been enhanced by
2304-630: A written test and having minimum levels of insurance. Formal training in the carpentry trade is available in seminars, certificate programs, high-school programs, online classes, in the new construction, restoration, and preservation carpentry fields. Sometimes these programs are called pre- apprenticeship training. In the modern British construction industry, carpenters are trained through apprenticeship schemes where general certificates of secondary education (GCSE) in Mathematics , English, and Technology help but are not essential. However, this
2400-437: Is a season check in the knot, as is often the case, it will offer little resistance to this tensile stress. Small knots may be located along the neutral plane of a beam and increase the strength by preventing longitudinal shearing . Knots in a board or plank are least injurious when they extend through it at right angles to its broadest surface. Knots which occur near the ends of a beam do not weaken it. Sound knots which occur in
2496-673: 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 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
2592-456: Is also greatly increased in strength thereby. Since the latewood of a growth ring is usually darker in color than the earlywood, this fact may be used in visually judging the density, and therefore the hardness and strength of the material. This is particularly the case with coniferous woods. In ring-porous woods the vessels of the early wood often appear on a finished surface as darker than the denser latewood, though on cross sections of heartwood
2688-573: Is also used to construct the formwork into which concrete is poured during the building of structures such as roads and highway overpasses. In the UK, the skill of making timber formwork for poured or in situ concrete is referred to as shuttering . Carpentry in the United States is historically defined similarly to the United Kingdom as the "heavier and stronger" work distinguished from a joiner "...who does lighter and more ornamental work than that of
2784-743: Is among the oldest building materials. The ability to shape it into tools, shelter, and weapons improved with technological advances from the Stone Age to the Bronze Age to the Iron Age . Some of the oldest archaeological evidence of carpentry are water well casings. These include an oak and hazel structure dating from 5256 BC, found in Ostrov, Czech Republic, and one built using split oak timbers with mortise and tenon and notched corners excavated in eastern Germany , dating from about 7,000 years ago in
2880-428: Is an important consideration. The weakening effect is much more serious when timber is subjected to forces perpendicular to the grain and/or tension than when under load along the grain and/or compression . The extent to which knots affect the strength of a beam depends upon their position, size, number, and condition. A knot on the upper side is compressed, while one on the lower side is subjected to tension. If there
2976-422: Is dark colored and firm, and consists mostly of thick-walled fibers which form one-half or more of the wood. In inferior oak, this latewood is much reduced both in quantity and quality. Such variation is very largely the result of rate of growth. Wide-ringed wood is often called "second-growth", because the growth of the young timber in open stands after the old trees have been removed is more rapid than in trees in
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3072-417: Is deemed the preferred route, as young people can earn and gain field experience whilst training towards a nationally recognized qualification. There are two main divisions of training: construction-carpentry and cabinetmaking. During pre-apprenticeship, trainees in each of these divisions spend 30 hours a week for 12 weeks in classrooms and indoor workshops learning mathematics, trade terminology, and skill in
3168-677: Is derived from the Latin carpentarius [artifex] , "(maker) of a carriage ." The Middle English and Scots word (in the sense of "builder") was wright (from the Old English wryhta , cognate with work ), which could be used in compound forms such as wheelwright or boatwright . In the UK , carpentry is used to describe the skill involved in first fixing of timber items such as construction of roofs, floors and timber framed buildings , i.e. those areas of construction that are normally hidden in
3264-560: Is difficult to control completely, especially when using mass-produced kiln-dried timber stocks. Heartwood (or duramen ) is wood that as a result of a naturally occurring chemical transformation has become more resistant to decay. Heartwood formation is a genetically programmed process that occurs spontaneously. Some uncertainty exists as to whether the wood dies during heartwood formation, as it can still chemically react to decay organisms, but only once. The term heartwood derives solely from its position and not from any vital importance to
3360-399: Is in the walls, not the cavities. Hence the greater the proportion of latewood, the greater the density and strength. In choosing a piece of pine where strength or stiffness is the important consideration, the principal thing to observe is the comparative amounts of earlywood and latewood. The width of ring is not nearly so important as the proportion and nature of the latewood in the ring. If
3456-486: Is known as secondary growth ; it is the result of cell division in the vascular cambium , a lateral meristem, and subsequent expansion of the new cells. These cells then go on to form thickened secondary cell walls, composed mainly of cellulose , hemicellulose and lignin . Where the differences between the seasons are distinct, e.g. New Zealand , growth can occur in a discrete annual or seasonal pattern, leading to growth rings ; these can usually be most clearly seen on
3552-431: Is laid down on the outside of the wood previously formed, it follows that unless a tree materially increases its production of wood from year to year, the rings must necessarily become thinner as the trunk gets wider. As a tree reaches maturity its crown becomes more open and the annual wood production is lessened, thereby reducing still more the width of the growth rings. In the case of forest-grown trees so much depends upon
3648-470: Is more complex. The water conducting capability is mostly taken care of by vessels : in some cases (oak, chestnut, ash) these are quite large and distinct, in others ( buckeye , poplar , willow ) too small to be seen without a hand lens. In discussing such woods it is customary to divide them into two large classes, ring-porous and diffuse-porous . In ring-porous species, such as ash, black locust, catalpa , chestnut, elm , hickory, mulberry , and oak,
3744-698: Is often hazardous work. Types of woodworking and carpentry hazards include: machine hazards, flying materials, tool projection, fire and explosion, electrocution, noise, vibration, dust, and chemicals. In the United States the Occupational Safety and Health Administration (OSHA) tries to prevent illness, injury, and fire through regulations. However, self-employed workers are not covered by the OSHA act. OSHA claims that "Since 1970, workplace fatalities have been reduced by more than 65 percent and occupational injury and illness rates have declined by 67 percent. At
3840-431: Is the rule. Some others never form heartwood. Heartwood is often visually distinct from the living sapwood and can be distinguished in a cross-section where the boundary will tend to follow the growth rings. For example, it is sometimes much darker. Other processes such as decay or insect invasion can also discolor wood, even in woody plants that do not form heartwood, which may lead to confusion. Sapwood (or alburnum )
3936-413: Is the younger, outermost wood; in the growing tree it is living wood, and its principal functions are to conduct water from the roots to the leaves and to store up and give back according to the season the reserves prepared in the leaves. By the time they become competent to conduct water, all xylem tracheids and vessels have lost their cytoplasm and the cells are therefore functionally dead. All wood in
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4032-400: Is then known as the latewood or summerwood. There are major differences, depending on the kind of wood. If a tree grows all its life in the open and the conditions of soil and site remain unchanged, it will make its most rapid growth in youth, and gradually decline. The annual rings of growth are for many years quite wide, but later they become narrower and narrower. Since each succeeding ring
4128-461: Is usually the latewood in which the thick-walled, strength-giving fibers are most abundant. As the breadth of ring diminishes, this latewood is reduced so that very slow growth produces comparatively light, porous wood composed of thin-walled vessels and wood parenchyma. In good oak, these large vessels of the earlywood occupy from six to ten percent of the volume of the log, while in inferior material they may make up 25% or more. The latewood of good oak
4224-921: The Michel Electric Handsaw Company , with the sole purpose of manufacturing and marketing the saw invented by Michel. The company later renamed itself Skilsaw 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 Skil patents, Art Emmons of Porter-Cable invented the direct-drive sidewinder saw in 1928. Recently smaller cordless circular saws with rechargeable 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
4320-401: The grain of the rest of the wood "flows" (parts and rejoins). Within a knot, the direction of the wood (grain direction) is up to 90 degrees different from the grain direction of the regular wood. In the tree a knot is either the base of a side branch or a dormant bud. A knot (when the base of a side branch) is conical in shape (hence the roughly circular cross-section) with the inner tip at
4416-429: The resin which increases the strength when dry. Such resin-saturated heartwood is called "fat lighter". Structures built of fat lighter are almost impervious to rot and termites , and very flammable. Tree stumps of old longleaf pines are often dug, split into small pieces and sold as kindling for fires. Stumps thus dug may actually remain a century or more since being cut. Spruce impregnated with crude resin and dried
4512-606: The stave churches in Norway from the 12th and 13th centuries. By the 16th century, sawmills were coming into use in Europe. The founding of America was partly based on a desire to extract resources from the new continent including wood for use in ships and buildings in Europe. In the 18th century part of the Industrial Revolution was the invention of the steam engine and cut nails . These technologies combined with
4608-460: The United States by the middle of the 19th century. A circular saw is a tool for cutting many materials such as wood , masonry , plastic , or metal and may be hand-held or mounted to a machine. In woodworking the term "circular saw" refers specifically to the hand-held type and the table saw and chop saw are other common forms of circular saws. "Skilsaw" and "Skil saw" have become generic trademarks for conventional hand-held circular saws in
4704-410: The United States of America. Circular saw blades are specially designed for each particular material they are intended to cut and in cutting wood are specifically designed for making rip-cuts , cross-cuts, or a combination of both. Circular saws are commonly powered by electricity, but may be powered by a gasoline engine or a hydraulic motor which allows it to be fastened to heavy equipment, eliminating
4800-522: The United States, that is, members of the United Brotherhood of Carpenters and Joiners of America , are required to pass a skills test to be granted official journeyperson status, but uncertified professional carpenters may also be known as journeypersons based on their skill level, years of experience, or simply because they support themselves in the trade and not due to any certification or formal woodworking education. Professional status as
4896-433: The addition of steel and bronze into construction. The year-to-year variation in tree-ring widths and isotopic abundances gives clues to the prevailing climate at the time a tree was cut. Wood, in the strict sense, is yielded by trees , which increase in diameter by the formation, between the existing wood and the inner bark , of new woody layers which envelop the entire stem, living branches, and roots. This process
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#17327733326644992-418: The annual rings of growth and the amount of sapwood. Within the same species the cross-sectional area of the sapwood is very roughly proportional to the size of the crown of the tree. If the rings are narrow, more of them are required than where they are wide. As the tree gets larger, the sapwood must necessarily become thinner or increase materially in volume. Sapwood is relatively thicker in the upper portion of
5088-410: The apprenticeship, they are known as journeyperson carpenters. Up through the 19th and even the early 20th century, the journeyperson traveled to another region of the country to learn the building styles and techniques of that area before (usually) returning home. In modern times, journeypeople are not required to travel, and the term now refers to a level of proficiency and skill. Union carpenters in
5184-461: The blade strikes the material, it makes a small chip. 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
5280-449: The border between the two classes, forming an intermediate group. In temperate softwoods, there often is a marked difference between latewood and earlywood. The latewood will be denser than that formed early in the season. When examined under a microscope, the cells of dense latewood are seen to be very thick-walled and with very small cell cavities, while those formed first in the season have thin walls and large cell cavities. The strength
5376-411: The building occupants. Wood Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants . It is an organic material – a natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in
5472-447: 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
5568-458: The cell walls are composed of micro-fibrils of cellulose (40–50%) and hemicellulose (15–25%) impregnated with lignin (15–30%). In coniferous or softwood species the wood cells are mostly of one kind, tracheids , and as a result the material is much more uniform in structure than that of most hardwoods . There are no vessels ("pores") in coniferous wood such as one sees so prominently in oak and ash, for example. The structure of hardwoods
5664-435: The central portion one-fourth the height of the beam from either edge are not serious defects. Knots do not necessarily influence the stiffness of structural timber; this will depend on the size and location. Stiffness and elastic strength are more dependent upon the sound wood than upon localized defects. The breaking strength is very susceptible to defects. Sound knots do not weaken wood when subject to compression parallel to
5760-445: The competition of the trees in their struggle for light and nourishment that periods of rapid and slow growth may alternate. Some trees, such as southern oaks , maintain the same width of ring for hundreds of years. On the whole, as a tree gets larger in diameter the width of the growth rings decreases. As a tree grows, lower branches often die, and their bases may become overgrown and enclosed by subsequent layers of trunk wood, forming
5856-490: The completion of an apprenticeship and an additional examination. After working as a journeyperson for a while, a carpenter may go on to study or test as a master carpenter. In some countries, such as Germany, Iceland and Japan , this is an arduous and expensive process, requiring extensive knowledge (including economic and legal knowledge) and skill to achieve master certification; these countries generally require master status for anyone employing and teaching apprentices in
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#17327733326645952-433: The contrast is conspicuous (see section of yew log above). This is produced by deposits in the heartwood of chemical substances, so that a dramatic color variation does not imply a significant difference in the mechanical properties of heartwood and sapwood, although there may be a marked biochemical difference between the two. Some experiments on very resinous longleaf pine specimens indicate an increase in strength, due to
6048-424: The craft. In others, like the United States, 'master carpenter' can be a loosely used term to describe any skilled carpenter. Fully trained carpenters and joiners will often move into related trades such as shop fitting , scaffolding , bench joinery , maintenance and system installation. Carpenters traditionally worked with natural wood which has been prepared by splitting (riving), hewing , or sawing with
6144-543: The design was invented, logs were sawn by hand using a pit saw or using powered saws in a sawmill using an up-and-down saw with a reciprocating 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 nickname buzz-saw . Sawmills first used smaller diameter circular saws to resaw dimension lumber such as lath and wall studs and for edging boards. As
6240-402: The early Neolithic period . Relatively little history of carpentry was preserved before written language. Knowledge and skills were simply passed down over the generations. Even the advent of cave painting and writing recorded little. The oldest surviving complete architectural text is Vitruvius ' ten books collectively titled De architectura , which discuss some carpentry. It was only with
6336-415: The end of a log, but are also visible on the other surfaces. If the distinctiveness between seasons is annual (as is the case in equatorial regions, e.g. Singapore ), these growth rings are referred to as annual rings. Where there is little seasonal difference growth rings are likely to be indistinct or absent. If the bark of the tree has been removed in a particular area, the rings will likely be deformed as
6432-403: The exact mechanisms determining the formation of earlywood and latewood. Several factors may be involved. In conifers, at least, rate of growth alone does not determine the proportion of the two portions of the ring, for in some cases the wood of slow growth is very hard and heavy, while in others the opposite is true. The quality of the site where the tree grows undoubtedly affects the character of
6528-505: The grain. In some decorative applications, wood with knots may be desirable to add visual interest. In applications where wood is painted , such as skirting boards, fascia boards, door frames and furniture, resins present in the timber may continue to 'bleed' through to the surface of a knot for months or even years after manufacture and show as a yellow or brownish stain. A knot primer paint or solution (knotting), correctly applied during preparation, may do much to reduce this problem but it
6624-412: The greater the water content, the greater its softening effect. The moisture in wood can be measured by several different moisture meters . Drying produces a decided increase in the strength of wood, particularly in small specimens. An extreme example is the case of a completely dry spruce block 5 cm in section, which will sustain a permanent load four times as great as a green (undried) block of
6720-834: The invention of the circular saw led to the development of balloon framing which was the beginning of the decline of traditional timber framing. The 19th century saw the development of electrical engineering and distribution which allowed the development of hand-held power tools, wire nails, and machines to mass-produce screws . In the 20th century, portland cement came into common use and concrete foundations allowed carpenters to do away with heavy timber sills. Also, drywall (plasterboard) came into common use replacing lime plaster on wooden lath. Plywood, engineered lumber, and chemically treated lumber also came into use. For types of carpentry used in America see American historic carpentry . Carpentry requires training which involves both acquiring knowledge and physical practice. In formal training
6816-580: The invention of the printing press in the 15th century that this began to change, albeit slowly, with builders finally beginning to regularly publish guides and pattern books in the 18th and 19th centuries. Some of the oldest surviving wooden buildings in the world are temples in China such as the Nanchan Temple built-in 782, Greensted Church in England, parts of which are from the 11th century, and
6912-407: The larger vessels or pores (as cross sections of vessels are called) are localized in the part of the growth ring formed in spring, thus forming a region of more or less open and porous tissue. The rest of the ring, produced in summer, is made up of smaller vessels and a much greater proportion of wood fibers. These fibers are the elements which give strength and toughness to wood, while the vessels are
7008-480: The moisture content of the air) retains 8–16% of the water in the cell walls, and none, or practically none, in the other forms. Even oven-dried wood retains a small percentage of moisture, but for all except chemical purposes, may be considered absolutely dry. The general effect of the water content upon the wood substance is to render it softer and more pliable. A similar effect occurs in the softening action of water on rawhide, paper, or cloth. Within certain limits,
7104-421: The motor and the blade. In the type known colloquially as a sidewinder , the blade is mounted directly on the motor 's driveshaft . In a worm-drive saw, the blade is driven by a perpendicularly mounted motor using worm 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
7200-501: The need for a separate energy source. There is evidence for the prehistorical use of circular saws by people of Indus Valley Civilization during the Bronze Age. The same was excavated from the archeological site of Lothal , Gujarat . The modern-day circular saw was invented around the end of the 18th century as a rip-saw to convert logs into lumber in sawmills and various claims have been made as to who invented it. Before
7296-936: The next four years, as they progress in status to Second Year, Third Year, and Fourth Year Apprentice, apprentices periodically return to the training facility every three months for a week of more detailed training in specific aspects of the trade. In the United States, fewer than 5% of carpenters identify as female. A number of schools in the U.S. appeal to non-traditional tradespeople by offering carpentry classes for and taught by women, including Hammerstone: Carpentry for Women in Ithaca, NY, Yestermorrow in Waitsfield, VT and Oregon Tradeswomen in Portland, OR. Tradesmen in countries such as Germany and Australia are required to fulfill formal apprenticeships (usually three to four years) to work as professional carpenters. Upon graduation from
7392-511: 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
7488-542: The other hand, the latewood is very dense and is deep-colored, presenting a very decided contrast to the soft, straw-colored earlywood. It is not only the proportion of latewood, but also its quality, that counts. In specimens that show a very large proportion of latewood it may be noticeably more porous and weigh considerably less than the latewood in pieces that contain less latewood. One can judge comparative density, and therefore to some extent strength, by visual inspection. No satisfactory explanation can as yet be given for
7584-404: The plant overgrows the scar. If there are differences within a growth ring, then the part of a growth ring nearest the center of the tree, and formed early in the growing season when growth is rapid, is usually composed of wider elements. It is usually lighter in color than that near the outer portion of the ring, and is known as earlywood or springwood. The outer portion formed later in the season
7680-605: The point in stem diameter at which the plant's vascular cambium was located when the branch formed as a bud. In grading lumber and structural timber , knots are classified according to their form, size, soundness, and the firmness with which they are held in place. This firmness is affected by, among other factors, the length of time for which the branch was dead while the attaching stem continued to grow. Knots materially affect cracking and warping, ease in working, and cleavability of timber. They are defects which weaken timber and lower its value for structural purposes where strength
7776-411: The properties of the wood. Certain rot-producing fungi impart to wood characteristic colors which thus become symptomatic of weakness. Ordinary sap-staining is due to fungal growth, but does not necessarily produce a weakening effect. Water occurs in living wood in three locations, namely: In heartwood it occurs only in the first and last forms. Wood that is thoroughly air-dried (in equilibrium with
7872-468: The reverse is commonly true. Otherwise the color of wood is no indication of strength. Abnormal discoloration of wood often denotes a diseased condition, indicating unsoundness. The black check in western hemlock is the result of insect attacks. The reddish-brown streaks so common in hickory and certain other woods are mostly the result of injury by birds. The discoloration is merely an indication of an injury, and in all probability does not of itself affect
7968-455: 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
8064-453: The same size will. The greatest strength increase due to drying is in the ultimate crushing strength, and strength at elastic limit in endwise compression; these are followed by the modulus of rupture, and stress at elastic limit in cross-bending, while the modulus of elasticity is least affected. Wood is a heterogeneous , hygroscopic , cellular and anisotropic (or more specifically, orthotropic ) material. It consists of cells, and
8160-488: The same time, U.S. employment has almost doubled." The leading cause of overall fatalities, called the "fatal four," are falls, followed by struck by object, electrocution, and caught-in/between. In general construction "employers must provide working conditions that are free of known dangers. Keep floors in work areas in a clean and, so far as possible, dry condition. Select and provide required personal protective equipment at no cost to workers. Train workers about job hazards in
8256-455: The saw is. Saws of this size typically have a shear pin hole, off axis, that breaks if the saw is overloaded and allows the saw to spin free. The most common version is the ITCO (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
8352-542: The stems of trees, or more broadly to include the same type of tissue elsewhere, such as in the roots of trees or shrubs. In a living tree, it performs a mechanical-support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients among the leaves , other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, woodchips , or fibers . Wood has been used for thousands of years for fuel , as
8448-419: The technology advanced large diameter saw blades began to be used for the head saws and to cut clapboards . Claims to the invention of the circular saw include: Typically, the material to be cut is securely clamped or held in a vise , and the saw is advanced slowly across it. In variants such as the table saw , the saw is fixed and the material to be cut is slowly moved into the saw blade. As each tooth in
8544-416: 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
8640-430: The tree, may well be stronger than a piece of heartwood from the same tree. Different pieces of wood cut from a large tree may differ decidedly, particularly if the tree is big and mature. In some trees, the wood laid on late in the life of a tree is softer, lighter, weaker, and more even textured than that produced earlier, but in other trees, the reverse applies. This may or may not correspond to heartwood and sapwood. In
8736-445: The tree. This is evidenced by the fact that a tree can thrive with its heart completely decayed. Some species begin to form heartwood very early in life, so having only a thin layer of live sapwood, while in others the change comes slowly. Thin sapwood is characteristic of such species as chestnut , black locust , mulberry , osage-orange , and sassafras , while in maple , ash , hickory , hackberry , beech , and pine, thick sapwood
8832-416: The trunk of a tree than near the base, because the age and the diameter of the upper sections are less. When a tree is very young it is covered with limbs almost, if not entirely, to the ground, but as it grows older some or all of them will eventually die and are either broken off or fall off. Subsequent growth of wood may completely conceal the stubs which will remain as knots. No matter how smooth and clear
8928-441: The union entry fee and obtaining a journeyperson's card (which provides the right to work on a union carpentry crew) the carpenter foreperson will, by necessity, dismiss any worker who presents the card but does not demonstrate the expected skill level. Carpenters may work for an employer or be self-employed. No matter what kind of training a carpenter has had, some U.S. states require contractors to be licensed which requires passing
9024-430: The use of hand and power tools. Construction-carpentry trainees also participate in calisthenics to prepare for the physical aspect of the work. Upon completion of pre-apprenticeship, trainees who have passed the graded curriculum (taught by highly experienced journeyperson carpenters) are assigned to a local union and to union carpentry crews at work on construction sites or in cabinet shops as First Year Apprentices. Over
9120-554: The user does not need to lean across the saw to see the cutting line. Blades for cutting wood are almost universally tungsten 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
9216-418: The wood formed, though it is not possible to formulate a rule governing it. In general, where strength or ease of working is essential, woods of moderate to slow growth should be chosen. In ring-porous woods, each season's growth is always well defined, because the large pores formed early in the season abut on the denser tissue of the year before. In the case of the ring-porous hardwoods, there seems to exist
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