Sawmill

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

A sawmill (saw mill, saw-mill) or lumber mill is a facility where logs are cut into lumber. Modern sawmills 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" sawmill is of simple operation. The log lies 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 sawmill consists of a chainsaw and a customized jig ("Alaskan sawmill"), with similar horizontal operation.

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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.

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.

Pre-Industrial Revolution

Scheme of the water-driven sawmill at Hierapolis, Asia Minor. The 3rd-century mill incorporated a crank and connecting rod mechanism. Romische Sagemuhle.svg
Scheme of the water-driven sawmill at Hierapolis, Asia Minor. The 3rd-century mill incorporated a crank and connecting rod mechanism.
Illustration of a human-powered sawmill with a gang-saw, published in 1582. Fotothek df tg 0003845 Mechanik ^ Sage ^ Holz.jpg
Illustration of a human-powered sawmill with a gang-saw, published in 1582.
"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. Sawmill 'Salamander' in Leidschendam, Netherlands.jpg
"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 of Australia, c. 1900 A sawmill in the interior from The Powerhouse Museum Collection.jpg
A sawmill in the interior of Australia, c.1900
Modern reconstruction Sutter's mill in California, where gold was first found in 1848. Sutters mill.JPG
Modern reconstruction Sutter's mill in California, where gold was first found in 1848.

The Hierapolis sawmill, a water-powered stone sawmill 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. 1225-1235. [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] :8485

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] :9495 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]

A sawmill of Naistenlahti in Tampere, Finland, 1890s Naistenlahden saha.jpg
A sawmill of Naistenlahti in Tampere, Finland, 1890s

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.

Oregon Mill using energy efficient ponding to move logs Sawmill1.jpg
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 4,700-cubic-metre-per-day (2-million- board-foot -per- day ) per day capacity is up to CAN$120,000,000. A modern operation will produce between 240,000 to 1,650,000 cubic metres (100 to 700 million board feet) 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.

See also

Related Research Articles

Crankshaft

A crankshaft is a shaft driven by a crank mechanism, consisting of a series of cranks and crankpins to which the connecting rods of an engine is attached. It is a mechanical part able to perform a conversion between reciprocating motion and rotational motion. In a reciprocating engine, it translates reciprocating motion of the piston into rotational motion, whereas in a reciprocating compressor, it converts the rotational motion into reciprocating motion. In order to do the conversion between two motions, the crankshaft has "crank throws" or "crankpins", additional bearing surfaces whose axis is offset from that of the crank, to which the "big ends" of the connecting rods from each cylinder attach.

Ausonius Late Roman poet

Decimius Magnus Ausonius was a Roman poet and teacher of rhetoric from Burdigala in Aquitaine, modern Bordeaux, France. For a time he was tutor to the future emperor Gratian, who afterwards bestowed the consulship on him. His best-known poems are Mosella, a description of the river Moselle, and Ephemeris, an account of a typical day in his life. His many other verses show his concern for his family, friends, teachers, and circle of well-to-do acquaintances and his delight in the technical handling of meter.

Circular saw Power tool

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.

Watermill Structure that uses a water wheel or turbine

A watermill or water mill is a mill that uses hydropower. It is a structure that uses a water wheel or water turbine to drive a mechanical process such as milling (grinding), rolling, or hammering. Such processes are needed in the production of many material goods, including flour, lumber, paper, textiles, and many metal products. These watermills may comprise gristmills, sawmills, paper mills, textile mills, hammermills, trip hammering mills, rolling mills, wire drawing mills.

A saw is a tool consisting of a tough blade, wire, or chain with a hard toothed edge. It is used to cut through material, very often wood though sometimes metal or stone. The cut is made by placing the toothed edge against the material and moving it forcefully forth and less forcefully back or continuously forward. This force may be applied by hand, or powered by steam, water, electricity or other power source. An abrasive saw has a powered circular blade designed to cut through metal or ceramic.

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.

Rip cut

In woodworking, a rip-cut is a type of cut that severs or divides a piece of wood parallel to the grain. The other typical type of cut is a cross-cut, a cut perpendicular to the grain. Unlike cross-cutting, which shears the wood fibers, a rip saw works more like a series of chisels, lifting off small splinters of wood. The nature of the wood grain requires the shape of the saw teeth to be different thus the need for both rip saws and crosscut saws; however some circular saw blades are combination blades and can make both types of cuts. A rip cut is the fundamental type of cut made at a sawmill.

Crank (mechanism) Simple machine transferring motion to or from a rotaing shaft at a distance from the centreline

A crank is an arm attached at a right angle to a rotating shaft by which circular motion is imparted to or received from the shaft. When combined with a connecting rod, it can be used to convert circular motion into reciprocating motion, or vice versa. The arm may be a bent portion of the shaft, or a separate arm or disk attached to it. Attached to the end of the crank by a pivot is a rod, usually called a connecting rod (conrod).

Connecting rod

A connecting rod is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the crankshaft. The connecting rod is required to transmit the compressive and tensile forces from the piston. In its most common form, in an internal combustion engine, it allows pivoting on the piston end and rotation on the shaft end.

Bandsaw

A bandsaw is a power saw with a long, sharp blade consisting of a continuous band of toothed metal stretched between two or more wheels to cut material. They are used principally in woodworking, metalworking, and lumbering, but may cut a variety of materials. Advantages include uniform cutting action as a result of an evenly distributed tooth load, and the ability to cut irregular or curved shapes like a jigsaw. The minimum radius of a curve is determined by the width of the band and its kerf. Most bandsaws have two wheels rotating in the same plane, one of which is powered, although some may have three or four to distribute the load. The blade itself can come in a variety of sizes and tooth pitches, which enables the machine to be highly versatile and able to cut a wide variety of materials including wood, metal and plastic.

Ancient Roman engineering

The ancient Romans were famous for their advanced engineering accomplishments. Technology for bringing running water into cities was developed in the east, but transformed by the Romans into a technology inconceivable in Greece. The architecture used in Rome was strongly influenced by Greek and Etruscan sources.

Saw pit

A saw pit or sawpit is a pit over which lumber is positioned to be sawed with a long two-handled saw by two people, one standing above the timber and the other below. It was used for producing sawn planks from tree trunks, which could then be cut down into boards, pales, posts, etc. Many towns, villages and country estates had their own saw pits. The greatest user of sawn timber in past centuries was the shipbuilding industry.

Frame saw

A frame saw or sash saw is a type of saw which consists of a relatively narrow and flexible blade held under tension within a rectangular frame. They are used for cutting wood or stone. The blade is held perpendicular to the plane of the frame, so that the material being cut passes through the center of the frame. Frame saws for use with wood are rip saws operated as a hand saw or powered in a sawmill. Frame saws used for cutting stone were powered saws in stone mills.

Hierapolis sawmill

The Hierapolis sawmill was a Roman water-powered stone sawmill at Hierapolis, Asia Minor. Dating to the second half of the 3rd century AD, the sawmill is considered the earliest known machine to combine a crank with a connecting rod to form a crank slider mechanism.

Chainsaw mill

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

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.

Kin Kin Sawmill

Kin Kin Sawmill is a heritage-listed sawmill at 1 Sister Tree Creek Road, Kin Kin, Shire of Noosa, Queensland, Australia. It was built in 1940s. It was added to the Queensland Heritage Register on 27 November 2008.

A swingblade sawmill utilizes a single circular sawblade which pivots about a 90 degree point, to saw in both vertical and horizontal planes. The single blade travels horizontally in one direction down the log, and returns in vertical position, thus removing a sawn piece of timber. The swingblade head unit is normally mounted on a moving frame that travels along a track or tracks, up and down a stationary log.

Flat sawing Woodworking process

Flat sawing, flitch sawing or plain sawing is a woodworking process that produces flat cut or plain cut boards of lumber.

References

  1. "Lumber Manufacturing". Lumber Basics. Western Wood Products Association. 2002. Retrieved 2008-02-12.
  2. 1 2 Ritti, Grewe & Kessener 2007 , p. 161
  3. Ritti, Grewe & Kessener 2007 , pp. 149–153
  4. 1 2 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 Culture46 (1): 1-30 [o10-1]
  6. C. Singer et at., History of Technology II (Oxford 1956), 643-4.
  7. 1 2 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. 1 2 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. "RitchieSpecs Equipment Specs & Dimensions". www.ritchiespecs.com.
  13. "Reap the Profits of Mobile Milling". Trees 2 Money. Retrieved 2016-03-10.

Sources