more at http://hardware.quickfound.net/ Construction of second homes in the country, using plenty of Douglas Fir plywood. Public domain film from the Prelinger Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied. The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original). http://creativecommons.org/licenses/by-sa/3.0/ http://en.wikipedia.org/wiki/Plywood Plywood is a sheet material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured boards which includes medium-density fibreboard (MDF) and particle board (chipboard). All plywoods bind resin and wood fiber sheets (cellulose cells are long, strong and narrow) to form a composite material. This alternation of the grain is called cross-graining and has several important benefits: it reduces the tendency of wood to split when nailed at the edges; it reduces expansion and shrinkage, providing improved dimensional stability; and it makes the strength of the panel consistent across all directions. There are usually an odd number of plies, so that the sheet is balanced—this reduces warping. Because plywood is bonded with grains running against one another and with an odd number of composite parts, it is very hard to bend it perpendicular to the grain direction of the surface ply. Smaller thinner plywoods and lower quality plywoods... may only have their plies (layers) arranged at right angles to each other, though many better quality plywood products will by design have five plies in steps of 45 degrees (0, 45, 90, 135, and 180 degrees), giving strength in multiple axis. The highest quality specialty plywoods often have plies at 30 degrees (0, 30, 60, 90, 120, 150, and 180 degrees) in seven layers, or have nine layers with two layers of 45 and 135 degrees in the sandwich. The smaller the step rotations the harder it is to manufacture, increasing manufacturing costs and consequently retail price. History In 1797 Samuel Bentham applied for patents covering several machines to produce veneers. In his patent applications, he described the concept of laminating several layers of veneer with glue to form a thicker piece – the first description of what we now call plywood. Samuel Bentham was a British naval engineer with many shipbuilding inventions to his credit. Veneers at the time of Bentham were flat sawn, rift sawn or quarter sawn; i.e. cut along or across the log manually in different angles to the grain and thus limited in width and length. About fifty years later Immanuel Nobel, father of Alfred Nobel, realized that several thinner layers of wood bonded together would be stronger than one single thick layer of wood... ...in its 1870 edition, the French dictionary Robert describes the process of rotary lathe veneer manufacturing in its entry Déroulage. One can thus presume that rotary lathe plywood manufacture was an established process in France in the 1860s. Plywood was introduced into the United States in 1865 and industrial production started shortly after. In 1928, the first standard-sized 4 ft by 8 ft (1.2 m by 2.4 m) plywood sheets were introduced in the United States for use as a general building material... http://en.wikipedia.org/wiki/Douglas_fir Douglas fir, with the scientific name Pseudotsuga menziesii, also known as Oregon pine or Douglas spruce, is an evergreen conifer species native to western North America... Douglas fir is one of the world's best timber producers and yields more timber than any other tree in North America. The wood is used for dimensional lumber, timbers, pilings, and plywood. Creosote treated pilings and decking are used in marine structures. The wood is also made into railroad ties, mine timbers, house logs, posts and poles, fencing, flooring, pulp, and furniture. Douglas fir is used extensively in landscaping. It is planted as a specimen tree or in mass screenings. It is also a popular Christmas tree. This plant has ornamental value in large parks and gardens, and has gained the Royal Horticultural Society's Award of Garden Merit. Away from its native area, it is also extensively used in forestry as a plantation tree for timber in Europe, New Zealand, Chile and elsewhere. It is also naturalised throughout Europe, Argentina and Chile (called Pino Oregón), and in New Zealand sometimes to the extent of becoming an invasive species (termed a wilding conifer) subject to control measures. The buds have been used to flavor eau de vie, a clear, colorless fruit brandy. Native Hawaiians built waʻ kaulua (double-hulled canoes) from coast Douglas fir logs that had drifted ashore...

• published: 17 Jan 2015
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