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Unformatted text preview: Test 3 study guide Chapter 3 Advantages of wood: Strong and stiff like concrete Light in weight vs. concrete Easily shaped and easy to work on Fastens together quickly and economical Recyclable and sustainable material Biodegradable Renewable resource Disadvantages: Not perfectly straight or precise b/c natural material Size and shape are affected by moisture (twist or bend) Contains growth defects Can split and warp Burns easily and requires fire protection Decays with contact of water Susceptible to insect damage Components of lumber: Bark (dead layer) Cambium (thin, alive, and replenishing mechanism for bark) Sapwood (all nutrients of the tree are located here) Heartwood (gives strength to tree) Pith (innermost circle; weak and soft) Trees Cells and growth Primarily hollow circular cells; axis running parallel to tree (grain direction); Tough cellulose bound by lignin (impacts the properties of wood ie strength and appearance) Early Wood : Springwood Cells if the tree is exposed to more water; faster growth; cells are larger and less dense Latewood : Summerwood slower growth; cells smaller and denser HW (hardwood) : Oak; poplar SW (softwood) : Pine Uses: Structural Framing- softwood mainly Subfloors and sheathing- wood panels Siding- Structural and exposed- usually some use of softwood Finish- cabinetry and trim- usually hardwood to get desired texture Lumber Production: Sawing 1.Plain Sawing: use framing lumber usually because dont care about appearance care about strength; maximum yield (want to get as many pieces as possible); varying grain pattern 2.Quarter Sawing: design oriented (splits circle into quarters); perpendicular to annual rings; less yield, but consistent grain pattern; behaves better (less distortion) and improved quality (of wearing); used for flooring or exposed uses 3. Typical Sawing Method: most typical, dont care about pattern Lumber Drying: Methods: Air or Kiln Effects of Drying: o Shrinkage (caused by water draining by wood) Differential shrinkage- depending on where and what ring you are cutting wood will twist and deform; distortions that occur during drying o Reduced weight (caused by lack of water) o Increased strength and stiffness o More stable in cutting and stable in dimension Lumber Surfacing: Purpose: depends on if wood is exposed or not; smooth; dimensional precision Designation: S2S (2 sides sanded) S4S (4 sides sanded; done after drying Lumber Defects: Growth Defects: Knots and holes- reduce structural strength; Decay and/or insect damage...
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This note was uploaded on 11/14/2010 for the course CM 2121 taught by Professor Spring during the Fall '08 term at LSU.
- Fall '08