Wood suitable for Furniture: The sapwood is the outermost ring of a living tree that supplies water from its roots to all the leaves of the tree, while heartwood is the central dead portion of a log of tree. Termites eat the sapwood but rarely attack the heartwood; In many of the tree species the heartwood is usually of a darker colour, and is drier, denser and harder compared to sapwood. However sapwood has a smoother finish, while heartwood usually has eyes or knots (branch nodes) in it. Wood is a very complex material and there are many variables controlling its properties. Differences in species and natural variations in grain pattern, density and the amount of sapwood/heartwood result in a certain amount of variability in the final moisture content. Still the averages can be applied. Timber is a type of solid lumber wood that offer exceptional structural qualities, but it also lends a warmth that can only come from the deep and rich grain of solid wood. Drying lumber, either naturally (air drying) or in a kiln is the process to lower the moisture content. As wood dries, most of its strength properties increase. However, will continue to absorb or give off moisture with changes in humidity and temperature of the surrounding air. More humid air surrounding will cause wood to expand; drier air will cause wood to contract. This movement cannot be stopped. The greatest movement is across the grain. There is very little movement along the length. Movement across the grain is also greatly influenced by how a board was sawn. Furniture moved from one part of the world to another may change enough in dimension that it must be reworked to function correctly. 1. Composite/engineered woodPlywood is stable; it does not expand and contract like solid wood. As it is manufactured, wider pieces can be acquired. It is resistance to cracking, shrinkage, and twisting/warping, and has a general high degree of strength. Its made with alternate grain layers which gives it cumulative strength, even the sides are strong for screws. No beading needed, just sanding or slicing. It is bonded with melamine urea formaldehyde synthetic resin (IS:848:1974) and compressed by Hydraulic Hot Press with high temperature and pressure to make smooth, warp free, strong & durable quality & resistant to termite, borers, fungus. Plywood has a tendency to bend or sag in the middle when very lengthy pieces are used. Hence whenever the length of boards exceeds 7 feet or so, using blockboard is preferred. Blockboards are stronger but on the grain side but there rest of the sides are not strong at all (cannot hold screw). This is the reason why wardrobe doors, book shelves and panels are often made using blockboards. However, neither can we be sure if there are wide gaps inside the board, nor can we be sure of its strength. OSB (Oriented Strand Board) is a cheaper material (like MDF but instead of using wood dust its) made out of shredded wood strips and large shavings, bonded together with resins glue and wax, by applying high heat and pressure. However they generally contains less urea-formaldeyde than plywood. They are used for flooring, roofs, floors and packaging. Plywood quality (3-ply, 5-ply, 13-ply)
2. Solid lumber wood
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"Man is a Tool-using animal. Weak in himself, and of small stature, he stands on a basis, at most for the flattest-soled, of some half-square foot, insecurely enough; has to straddle out his legs, lest the very wind supplant him. Feeblest of bipeds! Three quintals [hundredweights] are a crushing load for him; the steer of the meadow tosses him aloft, like a waste rag. Nevertheless he can use Tools, can devise Tools: with these the granite mountain melts into light dust before him; he kneads glowing iron, as if it were soft paste; seas are his smooth highway, winds and fire his unwearying steeds. Nowhere do you find him without Tools: without Tools he is nothing, with Tools he is all." Thomas Carlyle, Sartor Resartus CNC Etching or Engraving is done by a high-powered spinning mill (with a bit head) that removes material from the top of wooden plank to make a decorative drawing or pattern.
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