Sawmill

A sawmill or lumber mill is a facility where logs are cut into lumber. Modern saw mills use a motorized saw to cut logs lengthwise to make long pieces, and crosswise to length depending on standard or custom sizes (dimensional lumber). The "portable" saw mill is iconic and of simple operation—the logs lay flat on a steel bed and the motorized saw cuts the log horizontally along the length of the bed, by the operator manually pushing the saw. The most basic kind of saw mill consists of a chainsaw and a customized jig ("Alaskan saw mill"), with similar horizontal operation.

Before the invention of the sawmill, boards were made in various manual ways, either rived (split) and planed, hewn, or more often hand sawn by two men with a whipsaw, one above and another in a saw pit below. The earliest known mechanical mill is the Hierapolis sawmill, a Roman water-powered stone mill at Hierapolis, Asia Minor dating back to the 3rd century AD. Other water-powered mills followed and by the 11th century they were widespread in Spain and North Africa, the Middle East and Central Asia, and in the next few centuries, spread across Europe. The circular motion of the wheel was converted to a reciprocating motion at the saw blade. Generally, only the saw was powered, and the logs had to be loaded and moved by hand. An early improvement was the development of a movable carriage, also water powered, to move the log steadily through the saw blade.

By the time of the Industrial Revolution in the 18th century, the circular saw blade had been invented, and with the development of steam power in the 19th century, a much greater degree of mechanisation was possible. Scrap lumber from the mill provided a source of fuel for firing the boiler. The arrival of railroads meant that logs could be transported to mills rather than mills being built besides navigable waterways. By 1900, the largest sawmill in the world was operated by the Atlantic Lumber Company in Georgetown, South Carolina, using logs floated down the Pee Dee River from the Appalachian Mountains. In the 20th century the introduction of electricity and high technology furthered this process, and now most sawmills are massive and expensive facilities in which most aspects of the work is computerized. Besides the sawn timber, use is made of all the by-products including sawdust, bark, woodchips, and wood pellets, creating a diverse offering of forest products.

Cutting wood with a portable sawmill
Sawing logs into finished lumber with a basic "portable" saw mill.
American sawmill, circa 1920
An American sawmill, circa 1920
Traditional sawmill - Jerome, Arizona
Early 20th-century sawmill, maintained at Jerome, Arizona.

Sawmill process

A sawmill's basic operation is much like those of hundreds of years ago; a log enters on one end and dimensional lumber exits on the other end.

  • After trees are selected for harvest, the next step in logging is felling the trees, and bucking them to length.
  • Branches are cut off the trunk. This is known as limbing.
  • Logs are taken by logging truck, rail or a log drive to the sawmill.
  • Logs are scaled either on the way to the mill or upon arrival at the mill.
  • Debarking removes bark from the logs.
  • Decking is the process for sorting the logs by species, size and end use (lumber, plywood, chips).
  • A sawyer uses a head saw (also called head rig or primary saw) to break the log into cants (unfinished logs to be further processed) and flitches (unfinished planks).
  • Depending upon the species and quality of the log, the cants will either be further broken down by a resaw or a gang edger into multiple flitches and/or boards.
  • Edging will take the flitch and trim off all irregular edges leaving four-sided lumber.
  • Trimming squares the ends at typical lumber lengths.
  • Drying removes naturally occurring moisture from the lumber. This can be done with kilns or air-dried.
  • Planing smooths the surface of the lumber leaving a uniform width and thickness.
  • Shipping transports the finished lumber to market.[1]

Pre-Industrial Revolution

Römische Sägemühle
Scheme of the water-driven sawmill at Hierapolis, Asia Minor. The 3rd-century mill incorporated a crank and connecting rod mechanism.[2]
Fotothek df tg 0003845 Mechanik ^ Säge ^ Holz
Illustration of a human-powered sawmill with a gang-saw published in 1582.
Sawmill 'Salamander' in Leidschendam, Netherlands
"De Salamander" a wind driven sawmill in Leidschendam, The Netherlands. Built in 1792, it was used until 1953, when it fell into disrepair. It was fully restored in 1989.
A sawmill in the interior from The Powerhouse Museum Collection
A sawmill in the interior of Australia, circa 1900
Sutters mill
Modern reconstruction Sutter's mill in California, where gold was first found in 1848.

The Hierapolis sawmill, a water-powered stone saw mill at Hierapolis, Asia Minor (modern-day Turkey, then part of the Roman Empire), dating to the second half of the 3rd century, is the earliest known sawmill. It also incorporates a crank and connecting rod mechanism.[2]

Water-powered stone sawmills working with cranks and connecting rods, but without gear train, are archaeologically attested for the 6th century at the Byzantine cities Gerasa (in Asia Minor) and Ephesus (in Syria).[3]

The earliest literary reference to a working sawmill comes from a Roman poet, Ausonius, who wrote a topographical poem about the river Moselle in Germany in the late 4th century AD. At one point in the poem he describes the shrieking sound of a watermill cutting marble.[4] Marble sawmills also seem to be indicated by the Christian saint Gregory of Nyssa from Anatolia around 370/390 AD, demonstrating a diversified use of water-power in many parts of the Roman Empire.[4]

By the 11th century, hydropowered sawmills were in widespread use in the medieval Islamic world, from Islamic Spain and North Africa in the west to Central Asia in the east.[5]

Sawmills later became widespread in medieval Europe, as one was sketched by Villard de Honnecourt in c. 1250.[6] They are claimed to have been introduced to Madeira following its discovery in c. 1420 and spread widely in Europe in the 16th century.[7]:84-85

Prior to the invention of the sawmill, boards were rived (split) and planed, or more often sawn by two men with a whipsaw, using saddleblocks to hold the log, and a saw pit for the pitman who worked below. Sawing was slow, and required strong and hearty men. The topsawer had to be the stronger of the two because the saw was pulled in turn by each man, and the lower had the advantage of gravity. The topsawyer also had to guide the saw so that the board was of even thickness. This was often done by following a chalkline.

Early sawmills simply adapted the whipsaw to mechanical power, generally driven by a water wheel to speed up the process. The circular motion of the wheel was changed to back-and-forth motion of the saw blade by a connecting rod known as a pitman arm (thus introducing a term used in many mechanical applications).

Generally, only the saw was powered, and the logs had to be loaded and moved by hand. An early improvement was the development of a movable carriage, also water powered, to move the log steadily through the saw blade.

A type of sawmill without a crank is known from Germany called "knock and drop" or simply "drop" -mills. In these drop sawmills, the frame carrying the saw blade is knocked upwards by cams as the shaft turns. These cams are let into the shaft on which the waterwheel sits. When the frame carrying the saw blade is in the topmost position it drops by its own weight, making a loud knocking noise, and in so doing it cuts the trunk.[8]

A small mill such as this would be the center of many rural communities in wood-exporting regions such as the Baltic countries and Canada. The output of such mills would be quite low, perhaps only 500 boards per day. They would also generally only operate during the winter, the peak logging season.

In the United States, the sawmill was introduced soon after the colonisation of Virginia by recruiting skilled men from Hamburg. Later the metal parts were obtained from the Netherlands,[7]:94-95 where the technology was far ahead of that in England, where the sawmill remained largely unknown until the late 18th century. The arrival of a sawmill was a large and stimulative step in the growth of a frontier community.

Industrial Revolution

Early mills had been taken to the forest, where a temporary shelter was built, and the logs were skidded to the nearby mill by horse or ox teams, often when there was some snow to provide lubrication. As mills grew larger, they were usually established in more permanent facilities on a river, and the logs were floated down to them by log drivers. Sawmills built on navigable rivers, lakes, or estuaries were called cargo mills because of the availability of ships transporting cargoes of logs to the sawmill and cargoes of lumber from the sawmill.[9]

The next improvement was the use of circular saw blades, perhaps invented in England in the late 18th century, but perhaps in 17th-century Holland, the Netherlands. Soon thereafter, millers used gangsaws, which added additional blades so that a log would be reduced to boards in one quick step. Circular saw blades were extremely expensive and highly subject to damage by overheating or dirty logs. A new kind of technician arose, the sawfiler. Sawfilers were highly skilled in metalworking. Their main job was to set and sharpen teeth. The craft also involved learning how to hammer a saw, whereby a saw is deformed with a hammer and anvil to counteract the forces of heat and cutting. Modern circular saw blades have replaceable teeth, but still need to be hammered.[10]

The introduction of steam power in the 19th century created many new possibilities for mills. Availability of railroad transportation for logs and lumber encouraged building of rail mills away from navigable water. Steam powered sawmills could be far more mechanized. Scrap lumber from the mill provided a ready fuel source for firing the boiler. Efficiency was increased, but the capital cost of a new mill increased dramatically as well.[9]

In addition, the use of steam or gasoline-powered traction engines also allowed the entire sawmill to be mobile.[11][12]

By 1900, the largest sawmill in the world was operated by the Atlantic Lumber Company in Georgetown, South Carolina, using logs floated down the Pee Dee River from as far as the edge of the Appalachian Mountains in North Carolina.

A restoration project for Sturgeon's Mill in Northern California is underway, restoring one of the last steam-powered lumber mills still using its original equipment.

Current trends

Sawmill1
Oregon Mill using energy efficient ponding to move logs

In the twentieth century the introduction of electricity and high technology furthered this process, and now most sawmills are massive and expensive facilities in which most aspects of the work is computerized. The cost of a new facility with 2 Mmfbm/day capacity is up to CAN$120,000,000. A modern operation will produce between 100 Mmfbm and 700 Mmfbm annually.

Small gasoline-powered sawmills run by local entrepreneurs served many communities in the early twentieth century, and specialty markets still today.

A trend is the small portable sawmill for personal or even professional use. Many different models have emerged with different designs and functions. They are especially suitable for producing limited volumes of boards, or specialty milling such as oversized timber. Portable sawmills have gained popularity for the convenience of bringing the sawmill to the logs and milling lumber in remote locations.[13] Some remote communities that have experienced natural disasters have used portable sawmills to rebuild their communities out of the fallen trees.

Technology has changed sawmill operations significantly in recent years, emphasizing increasing profits through waste minimization and increased energy efficiency as well as improving operator safety. The once-ubiquitous rusty, steel conical sawdust burners have for the most part vanished, as the sawdust and other mill waste is now processed into particleboard and related products, or used to heat wood-drying kilns. Co-generation facilities will produce power for the operation and may also feed superfluous energy onto the grid. While the bark may be ground for landscaping barkdust, it may also be burned for heat. Sawdust may make particle board or be pressed into wood pellets for pellet stoves. The larger pieces of wood that won't make lumber are chipped into wood chips and provide a source of supply for paper mills. Wood by-products of the mills will also make oriented strand board (OSB) paneling for building construction, a cheaper alternative to plywood for paneling. Some automatic mills can process 800 small logs into bark chips, wood chips, sawdust and sorted, stacked, and bound planks, in an hour.

Gallery

Laser guided cutting of wood inside modern woodmill

Inside a modern sawmill equipped with laser-guided technology

Laser guided cutting of wood in woodmill

Wood traveling on sawmill machinery

Sawdust waste from mill

Sawdust waste from the mill

D70-0745-armata-waterzaagmolen

A sawmill in Armata, on mount Smolikas, Epirus, Greece.

Gunton Saw Mill - geograph.org.uk - 1936852

A preserved water powered sawmill, Norfolk, England.

Sandakan Sabah Sawmill-20

Making planks from logs

Moulin à Scie (Luchon) - Fonds Ancely - B315556101 A MALBOS 1 011

Sawmill in Luchon, France, near 1840 by Eugène de Malbos

See also

References

  1. ^ "Lumber Manufacturing". Lumber Basics. Western Wood Products Association. 2002. Retrieved 2008-02-12.
  2. ^ a b Ritti, Grewe & Kessener 2007, p. 161
  3. ^ Ritti, Grewe & Kessener 2007, pp. 149–153
  4. ^ a b Wilson 2002, p. 16
  5. ^ Adam Robert Lucas (2005), "Industrial Milling in the Ancient and Medieval Worlds: A Survey of the Evidence for an Industrial Revolution in Medieval Europe", Technology and Culture 46 (1): 1-30 [o10-1]
  6. ^ C. Singer et at., History of Technology II (Oxford 1956), 643-4.
  7. ^ a b Peterson, Charles E. (1973). "Sawdust Trail: Annals of Sawmilling and the Lumber Trade from Virginia to Hawaii via Maine, Barbados, Sault Ste. Marie, Manchac and Seattle to the Year 1860". Bulletin of the Association for Preservation Technology. 5 (2): 84–153. doi:10.2307/1493399. JSTOR 1493399.
  8. ^ "Die Sägemühle". www.familienverband-tritschler.de (in German). Retrieved May 8, 2017.
  9. ^ a b Oakleaf p.8
  10. ^ Norman Ball, 'Circular Saws and the History of Technology' Bulletin of the Association for Preservation Technology 7(3) (1975), pp. 79-89.
  11. ^ Edwardian Farm: Roy Hebdige's mobile sawmill
  12. ^ Steam traction engines
  13. ^ "Reap the Profits of Mobile Milling". Trees 2 Money. Retrieved 2016-03-10.

Sources

  • Grewe, Klaus (2009), "Die Reliefdarstellung einer antiken Steinsägemaschine aus Hierapolis in Phrygien und ihre Bedeutung für die Technikgeschichte. Internationale Konferenz 13.−16. Juni 2007 in Istanbul", in Bachmann, Martin (ed.), Bautechnik im antiken und vorantiken Kleinasien (PDF), Byzas, 9, Istanbul: Ege Yayınları/Zero Prod. Ltd., pp. 429–454, ISBN 978-975-8072-23-1, archived from the original (PDF) on 2011-05-11
  • Ritti, Tullia; Grewe, Klaus; Kessener, Paul (2007), "A Relief of a Water-powered Stone Saw Mill on a Sarcophagus at Hierapolis and its Implications", Journal of Roman Archaeology, 20, pp. 138–163
  • Oakleaf, H.B. (1920), Lumber Manufacture in the Douglas Fir Region, Chicago: Commercial Journal Company
  • Wilson, Andrew (2002), "Machines, Power and the Ancient Economy", The Journal of Roman Studies, 92, pp. 1–32

External links

Chainsaw mill

An Alaskan mill or chainsaw mill is a type of sawmill that is used by one or two operators to mill logs into lumber for use in furniture, construction and other uses.

Circular saw

A circular 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 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. "Skil saw" has become a generic trademark for conventional hand-held circular saws. 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 the need for a separate energy source.

Gravy

Gravy is a sauce often made from the juices of meats that run naturally during cooking and thickened with wheat flour or corn starch for added texture. The term can refer to a wider variety of sauces. The gravy may be further colored and flavored with gravy salt (a simple mix of salt and caramel food coloring) or gravy browning (gravy salt dissolved in water) or ready-made cubes and powders can be used as a substitute for natural meat or vegetable extracts. Canned and instant gravies are also available. Gravy is commonly served with roasts, meatloaf, rice, and mashed potatoes.

Great Works River

The Great Works River is a 30.6-mile-long (49.2 km) river in southwestern Maine in the United States. It rises in central York County and flows generally south past North Berwick to meet the tidal part of the Salmon Falls River at South Berwick.

The native Newichawannock band of Abenaki called it the Asbenbedick. In July 1634, William Chadbourne, James Wall and John Goddard arrived from England aboard the ship Pied Cow with a commission to build a sawmill and gristmill at the river's Assabumbadoc Falls. The sawmill they built, thought to be the first over-shot water-powered site in America, was located in the "Rocky Gorge" below today's Brattle Street bridge. Their sawmill was rebuilt with up to 20 saws on what was then the "Little River" in 1651 by Richard Leader, an engineer granted exclusive right to the water power. It was thereafter called the "Great mill workes," from which the Great Works River derives its present name.

Head saw

A head saw, framesaw, gang saw or head rig is the saw that makes the initial cuts in a log at a sawmill, turning a log into cants, or planks of wood.

Hydraulic debarker

A hydraulic debarker is a machine removing bark from wooden logs by the use of water under a pressure of 100 psia (6.8 atmospheres) or greater. Hydraulic debarking can reduce soil and rock content of bark, but may increase the water content. Debarking water may be recycled after effective settling, but suspended solids may increase wear on high-pressure pumps. Hydraulic debarking has declined where water quality problems have arisen.

Log pond

A log pond is a small natural lake or reservoir used for storage of wooden logs in readiness for milling at a sawmill. Although some mill ponds served this purpose for water powered sawmills, steam-powered sawmills used log ponds for transportation of logs near the mill; and did not require the elevation drop of watermill reservoirs.

Lumber edger

A lumber edger is a device with saws used to straighten and smooth rough lumber or bowed stock by making a cut along the sides of the boards. The result of this process is dimensional lumber.In a saw mill the edger is next in line from the head saw. The feed and press rollers on the edger are usually powered, passing the lumber through the machine. The length of feed and tables depends upon the lumber produced by the head saw.Edgers can be categorized as gang or shifting edgers. In gang edgers the saws remain stationary. In a shifting edger the saws can move left or right independently of one another. This allows setting the saws to best maximize the product that can be produced from a particular cant.

Magnolia Independent School District

Magnolia Independent School District is a public school district based in Magnolia, Texas (USA).

In addition to Magnolia, the district also serves the town of Stagecoach and the community of Pinehurst.

In 2010, the school district was rated "recognized" by the Texas Education Agency. In 2009, the school district was rated "academically acceptable" by the Texas Education Agency.

Ottawa-Carleton District School Board

The Ottawa-Carleton District School Board (OCDSB, known as English-language Public District School Board No. 25 prior to 1999) refers to both the institution responsible for the operation of all English public schools in the city of Ottawa, Ontario and its governing body. Like most school boards, the OCDSB is administered by a group of elected trustees and one director selected and appointed by the Board itself. Additionally, annually, two student trustees are selected per provincial regulation.

Every four years, within the context of the Ottawa municipal elections, an election is held within each of Ottawa's twelve trustee electoral zones to elect each trustee. Following election and annually thereafter, the Board of Trustees holds its organizational meeting, where the Board membership elects two of its members to the positions of chair and vice-chair of the Board. Chairs and membership of each of the Board's committees are also determined as part of the organizational meeting. In addition to the twelve trustees, two student trustees are elected by their peers, providing opportunities for the student body to become informed and involved in Board governance.

Planing mill

A planing mill is a facility that takes cut and seasoned boards from a sawmill and turns them into finished dimensional lumber. Machines used in the mill include the planer and matcher, the molding machines, and varieties of saws. In the planing mill planer operators use machines that smooth and cut the wood for many different uses.

Portable sawmill

Portable sawmills are sawmills small enough to be moved easily and set up in the field. They have existed for over 100 years but grew in popularity in the United States starting in the 1970s, when the 1973 oil crisis and the back-to-the-land movement had led to renewed interest in small woodlots and in self-sufficiency. Their popularity has grown exponentially since 1982, when the portable bandsaw mill was first commercialized.

Resaw

A resaw is a large band saw optimized for cutting timber along the grain to reduce larger sections into smaller sections or veneers. Resawing veneers requires a wide blade – commonly 2 to 3 inches (52–78 mm) – with a small kerf to minimize waste. Resaw blades of up to 1 inch (26 mm) may be fitted to a standard band saw. Many small and medium-sized sawmills use 1- to ​1 1⁄2-inch band saw blades.

Timber mills use larger resaws to rip large planks into smaller sizes. A typical mill sized resaw blade is eight inches wide and made with 16 gauge steel. Resaw blades can be identified by their straight back, as opposed to headsaws and doublecut blades, which have notched or toothed backs.

Robinson Mill, California

Robinson Mill (also, Robinson Mills, Robinson Ranch, Robinson Sawmill, Robinsons Mill, and Robinsons Rancho) is a census-designated place in Butte County, California. It lies at an elevation of 2654 feet (809 m). Robinson Mill's population was 80 at the 2010 census.

Sawmill, Arizona

Sawmill (Navajo: Niʼiijííh Hasání) is a census-designated place (CDP) in Apache County, Arizona, United States. Sawmill is a part of Fort Defiance Agency, which is on the Navajo Nation. The population was 748 at the 2010 census. It is named after and developed around a sawmill. A trading post has been present since 1907.

Sawmill Fire

The Sawmill Fire was a wildfire that burned in Cloverdale, Sonoma County, California, in 2016. The fire, which started on September 25, burned 1,547 acres (6 km2) of land before being contained on September 29. Approximately 30 homes were evacuated and two minor injuries were reported. The fire was started by Border Patrol agent Dennis Dickey whilst shooting a target during his gender reveal party.

Sawmill Flat, California

Sawmill Flat is an unincorporated community in Fresno County, California. It is located 7.5 miles (12.1 km) northeast of Balch Camp, at an elevation of 6755 feet (2059 m).

Shingle weaver

A shingle weaver (US) or shingler (UK) is an employee of a wood products mill who engages in the creation of wooden roofing shingles or the closely related product known as "shakes." In the Pacific Northwest region of the United States, historically the leading producer of this product, such shingles are generally made of Western Red Cedar, an aromatic and disease-resistant wood indigenous to the area. The use of the term "weaver" for a shingle maker related to the way in which the workers fitted the shingles together in bundles but the meaning has extended to anyone who works in a shingle mill.

Trnovec, Kočevje

Trnovec (pronounced [təɾˈnoːʋəts]; German: Tiefenreuther or Tiefenreuter) is a settlement in the hills northeast of the town of Kočevje in southern Slovenia. It was a village inhabited by Gottschee Germans. At the start of the Second World War its original population was evicted. The area is part of the traditional region of Lower Carniola and is now included in the Southeast Slovenia Statistical Region.

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