Wood Technology Test #4 Notes PDF

23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes ========================================================= Lumber Grading: - - Very specialized trade Formal schooling “Inspectors” or “Graders” are certified for Hardwood or Softwood grading - Softwood and Hardwood have different grading crit...

23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes ========================================================= Lumber Grading: - - Very specialized trade Formal schooling “Inspectors” or “Graders” are certified for Hardwood or Softwood grading - Softwood and Hardwood have different grading criteria depending on application General: - Every piece of lumber is unique - Process sorts/group pieces of lumber into grade categories or “grades”, defined by Lumber Grading Rules - Purpose: Ensures pieces of lumber with “equivalent qualities” are assigned the same grade regardless of the log or mill it came from - Lumber Grading Rules Softwood Grading: - - Types: - Dimensional Lumber - Surfaced - Nominal 2”-4” thick - 2” or more wide - Designed for use as framing members such as joists, planks, rafters, and studs - Main criteria is strength - Boards - 1” thick lumber for a variety of uses depending on appearance and to some degree strength Canadian Lumber Standards Accreditation Boards (CLS) - Controls identification and certification of softwood lumber to be used in, exported from, or manufactured in Canada - Each piece of lumber graded is stamped by agency grading material - Stamp information: - Registered trademark symbol of the grading agency - Mill or grader identity - Grade of lumber - Species or combination of species - Moisture content when lumber was surfaced 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes Hardwood Grading: - - - - National Hardwood Lumber Association - Founded in 1989 to standardize the grades for hardwood lumber - Creator and keeper of the North American hardwood lumber grading rules - Before the NJLA was created, lumber was graded by mills on an individual basis Terminology - Board Size vs Cutting Size - Cutting: Rectangular area on a board that is knot and defect free - Note: defects that will be removed when the board is dressed can be included in a clear cutting - Surface Measure (SM) - Area of the board in square feet rounded to the nearest whole number - Cutting Units (CU) - An area 1” wide and 1’ long Boards: - Rated based on how usable they are - Large clear cuttings are more usable than small clear cuttings - Factors: - 1. Dimensions of board in length and width - 2. Dimensions of the Clear Cuttings in length and width - 3. The number of Clear Cuttings - 4. Area of Clear Cuttings as a percentage of Total Board Area (Yield) Standard Grades: - Firsts & Seconds (FAS) - Best grade of hardwood lumber - Minimum 6” x 8’ long boards - 4” x 5’ or 3” x 7’ Cutting Size - Graded from the poorer side of the board - 83% yield - Use in applications requiring wide, long, attractive material - Select - Same as FAS minus a few characteristics - Minimum 4” x 6’ long boards - Graded from the best side of board - Use in applications where only one good face is visible - Grade of poor side can not be lower than No. 1 Common 23F_WOO1410_01 Wood Technology - - - Erik Rehm Test 3 Notes No. 1 Common - Graded same as FAS - Minimum 3” x 4’ board size (same on all commons) - 67% yield - Suitable for projects requiring medium to shorter lengths - Commonly referred to as “cabinetmaker’s grade” No. 2 Common - Graded same as FAS - 50% yield - Limited usefulness to cabinetmakers because of short lengths of clear cuttings No. 3 Common - Graded same as FAS - 25% yield - Firewood to cabinetmaking Veneer: Veneering - The art of facing a groundwork of suitable material with a very thin layer of wood (⅛” or less), meant for looks not strength Marquetry - Using veneer to produce pictorial designs Parquetry - Using veneer to produce geometric designs Flitch: - A section of a log that is about to be cut into veneer A stack of veneer sheets sliced form the log and kept in sequential order Book/Bundle - Typically 24 or 32 sequential veneers Leaf - A single sheet of veneer Art Deco Furniture: - French decorative style of the 1920s Simple furniture styles “Opulent (luxurious) use of exotic wood veneer” - Charles Boyce Leading example: Jacques Emile Ruhlmann 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes Traditional Veneering Tools: - Toothing plane Glue pot (hide glue) Veneer hammer (squeezes out excess glue and presses veneer flat) Modern Veneering Tools: - Toothing plane Urea resin glue Vacuum bag (14.7lbs/inch^2 of pressure) Types of Veneer: 1) Decorative - Used when veneering a) Appearance is important i) Factors: (1) Species (2) Figure b) Sources: i) Butt (stump) ii) Crotch iii) Burl c) Hardwood Veneer i) Available as: (1) Sheets: (a) With backing (b) Without backing (raw) (c) Individual leaves or multiple leaves joined together (d) Intended to be applied to a substrate (2) Manufactures Panels (a) Outer layer of hardwood veneer bonded to a panel at the factory d) Examples: i) Elm Burl (1) Incredibly fragile ii) Walnut Burl/Crotch/Butt 2) Substrate - Used to manufacture plywood a) Strength is important, appearance is not b) Usually softwood c) Used for: i) Inner plies of veneer core panel products 23F_WOO1410_01 Wood Technology ii) Erik Rehm Test 3 Notes Outer and inner plies of construction grade veneer core plywood Hardwood Veneer Thickness: - No longer standard thickness Different mills produce veneers of different thicknesses Trend toward thinner veneer Approximately 20 thou to 24 thou Production: 1) Log Selection a) Inspected for straightness and degree of defects b) Best logs are separated and sent to the veneer mill 2) Debarking a) Bark ground off log 3) Cutting log lengthwise a) Options: i) Left whole ii) Halves iii) Quarters 4) Conditioning a) Soaking, boiling i) Boiling ensures: (1) Minimal checking when veneers is slices (2) Knives stay sharp longer (3) Less wear and tear on machines b) All slicing methods require conditioning of the log (some logs are not soaked, sawn method) c) Log is soaked in hot water (80C to 100C) d) 12-72 hours depending on species e) Softens the wood fibres 5) Cutting a) Log to Veneer Slicing i) Vertical Slicing Machine (1) Flitch Table (a) Moves up and down (b) Flitch attached with dogs or vacuum (2) Knife Carriage (a) Secures both knife and pressure bar 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes (b) Advances with each slice (c) Amount of advance based on thickness of veneer required (3) Pressure Bar (a) Prevents splitting ahead of knife (4) Steps: (a) Veneer is sliced as the Flitch Table moves downward (b) Knife Carriage moves forward before each Flitch Table stroke (c) Veneer is kept in sequential order ii) Rotary slicing (1) Uses a massive lathe (2) Logs used are called peelers or bolts (a) Peelers rotated downward against pressure bar and knife (3) Pressure bar and knife mounted at centreline of peeler (4) Pressure bar pressed against peeler ahead of knife to prevent splitting (5) Can produce 200-400 ft of veneer per minute (6) Grain pattern is very distinctive (a) Continues tangential cut (b) Cannot masquerade as thicker saw lumber (7) Guillotine cuts sheets to length iii) Stay log or half round slicing (1) Set of heavy steel castings (stay long) mounted to a conventional lathe (2) Flitch secured to staylog (3) Produces an eccentric rotation of flitch (4) Flitch oriented to present radial/tangential or other faces to knife (5) Often uses to produce veneer from figured faces (crotch, burl, butt) (6) Arc produces additional veneer length (7) Veneer is kept in sequential order b) Log to Veneer Sawing i) Sawn method (1) Oldest method of veneer production (2) Produces a lot of waste and takes time (a) Expensive (3) Still used for: 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes (a) Extremely hard woods where boiling won’t soften the fibers enough for slicing (b) Brittle woods that would be damaged by slicing (c) Species where the colour of wood will be affected by soaking (4) Band saw or circular saw is used (5) Flitch of green wood secured to movable saw carriage (6) Carriage moves flitch past the blade (7) Veneer is kept in sequential order c) Board to Veneer i) Lengthwise Slicing (1) Creating veneer from boards rather than logs (2) Boards are first streamed for 6-48 hours (3) Stationary blade slices moving board lengthwise Knife Checks: - - - As the knife separates veneer from flitch, the separated wood is severely bent Veneer will crack if the bending stresses exceed the strength of the wood - Cracks are called knife checks - Occur on the knife side of the veneer Knife checks close up when the veneer lays flat (not obvious to the naked eye) Common consequences: - Parallel-to-grain cracks through the finish on the veneered surface - May not appear for months or years - When possible, the loose side should be the one spread with glue - Not possible with some veneer matching patterns such as book matched Loose side - Flexes more easily Tight side - Doesn’t flex as well Veneer Drying: - - 2 common methods: - 1. Progressive Conveyor Method - 2. Progressive Platen Method (continuous pressing of veneer to squeeze out moisture) Feed rate is determined by: - Species - Thickness - Starting MC 23F_WOO1410_01 Wood Technology - Erik Rehm Test 3 Notes Desired MC Veneer Clipping: - Books of veneer are cut straight along ends and edges Sometimes used to remove sapwood Some species and many burls are not clipped Veneer Matching Patterns: - Front and back of each leaf of veneer is virtually identical due to being so thin - Mirror image Either side of leaf can be used (beware of knife checks) Sequential leaves can be arranged to create various veneer matching patterns - ***Name associated with a matching pattern usually refers to the pattern/design created by the grain of the wood, not the shape of the veneer seams 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes Advantages of Veneer on Substrate vs Solid Wood: - Allows use of woods that would be unobtainable/impractical as solid lumber - Ex. Crotch, butt, burl Reduces cost of wood Conserves wood species Permit precise matching of grain Large surface areas are already prepared - Use of pre-veneered panels vs. glue up of individual boards Dimensionally stable (driven by substrate material) Disadvantages of Veneer on Substrate vs Solid Wood: - - Loss of “status” - Perception by some that veneer on substrate is of lesser quality than solid wood Risk of sand through Edge of substrate must be concealed Limited options in the use of traditional joinery Board Foot Calculations: Board Foot (BdFt): A measure of volume, equal to 144 cubic inches, the actual shape of the item can vary - To determine the # of BdFt, divide the volume in cubic inches by 144 - Volume (BdFt) = Volume (in. cubed) / 144 Cut List: - List of material required for a project - Includes Quantity, Dimensions, and Material for each board - Format for Size and Quantity: - # @ (Quantity) #” (Grain Direction) x #” (Cross-Grain Direction) x #” (Thickness) Rough Sawn Lumber vs Surfaced Lumber: - Rough Sawn: - Cut - Dried - Thickness: 23F_WOO1410_01 Wood Technology - Erik Rehm Test 3 Notes - Ordered in “quarters” - “Nominal” thickness before drying - Not all thickness will be available from all suppliers - Not all thickness will be available in all species Surfaced Lumber: - “Dressed Lumber” - Rough sawn lumber that has been jointed and planed to create smooth surfaces - Joining and planning process makes the board thinner - Process: - Start with rough sawn lumber that is thicker than required - Create smooth parallel surfaces and square edges by removing material with jointer, planer, etc. - Approximately ⅛” removed from each face - Board thickness reduced by approximately ¼” - More material removed from boards with twist or bow - 4/4 lumber typically becomes ¾” thick after surfacing - 8/4 lumber typically becomes 1 ¾” thick after surfacing - Order rough lumber that is at least ¼” thicker than your surfaced lumber thickness requirement Shrinkage: - Board foot quantities are measured while wood is green Lumber shrinks while drying Unless otherwise stated, add 7% to your lumber requirements to account for shrinkage Wastage: - - Unable to use 100% of lumber purchased - FAS yield of 83% => 17% wastage - Select yield of 83% => 17% wastage - No. 1 Common yield of 67% => 33% wastage Component sizes may not match clear cuttings Some clear cutting may not be considered acceptable for other reasons (sapwood, figure, colour, etc.) A wastage factor must be added when ordering lumber (depends on species) Applying a 7% factor and then applying a 25% factor IS NOT the same as applying a 32% factor. Apply shrinkage factor first, then apply wastage factor. 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes BdFt Calculations with Multiple Boards: 1) Determine rough lumber thickness for each board size 2) Group Boards with same rough lumber thickness together 3) For each unique rough lumber thickness: a) Determine volume (cubic inches) for each board size, multiple by the quantity of boards at that specific size b) Add volume of all boards with the same rough lumber thickness together c) Convert into BdFt d) Apply Shrinkage factor e) Apply Wastage factor f) Round up to nearest whole BdFt value Wood Dust - Filtering Dust Collector: - The air exhausted by the dust collector will contain some small wood particles If dust collector is located outdoors => No big deal If dust collector is located in the shop => Wood particles exhausted by dust collector will be in air Level of air filtration on dust collectors varies from product to product Process: 1) Air and Wood Dust from tools is drawn into dust collector through ducting 2) Wood dust is separated from the air 3) Air is exhausted by the dust collector Micron - 1 micrometer, 1 millionth of a meter, 1 thousandth of a millimeter, 0.001 mm, 0.000001 meter (it’s really freaking small) - Wood particles created by tools can range from a fraction of an inch down to a fraction of a micron Designing air filters to trap large particles is easy - Designing them to trap fine particles is more difficult - The best dust collectors will filter out both the large and small particles before exhausting the air 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes Types of Air Filters: - Pleated Cartridge Filter Cloth Bag Filter HEPA Air Filters - High Efficiency Particulate Air Filter - Removes at least 99.97% of airborne particles 0.3 micrometers in diameter Bottom Line: When purchasing a dust collector, make sure you understand the level of air filtration provided by the unit Manufactured Sheet and Panel Products Types: - Composite Panels - Made from small wood pieces / wood fibers and adhesives - Particleboard - Engineered wood product - Made of wood particles: chips, splinters, shavings, and flakes - Particles mixed with a bonding agent (glue) - Mixture formed into sheets - Ideal substrate for veneering projects - Manufacturing methods: - Extrusion Method (Play-Doh Fun Factory) - Board formed by forcing particles/bonding argent mixture through a small heated opening - Boards are not pressed flat after extrusion - Process results in random orientation of particles - Minor thickness variations throughout board - Least common method - Mat Formed Method - Most common method - Particles and binder are formed into mats - Mats pressed into sheets 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes - - - - - Results in a product with a hard dense smooth surface with uniform thickness 2 types: - Single Layer - Same size particles throughout the sheet - Heavier due to amount of glue - Multilayer - Outside layers => fine particles - Inside Layer => coarser particles - Reduces weight while still providing a hard, dense, smooth surface Wind Sifting: - Particles of different densities are thrown in the air and blown by wind to be separated Process: - 1. Chipping and Flaking - 2. Drying - 3. Screening - 4. Blending with Adhesive - 5. Forming - 6. Pressing - 7. Cooling and Curing - 8. Sizing - 9. Sanding Specialty Types: - Fire Resistant - Includes additives that retard the spread of fire - Intended for use in commercial buildings where building code limits flame spread and smoke generation - Moisture Resistant - Sheltered exterior application - Waterproof glue - Anti-Static - Will not generate static electricity - For use in areas with sensitive electronic equipment 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes - - General Grades: - High Density - Medium Density - Low Density - Specific Grades: - M-0 - M-1 - M-S (commonly used) - M-2 (commonly used) - M-3i - Bonding Systems: - Type 1: - Urea Formaldehyde Resin - Interior use only (not waterproof) - Unprotected edges will wick water from any source, causing the individual particles to expand - To reduce risk of moisture damage, edges should be sealed or protected in some way - Type 2: - Phenol Formaldehyde Resin - Greater heat/moisture resistance - NAF: - No Added Formaldehyde - Created in response to consumer demand - Sizes: - Thickness => ¼” to 2 ¼” - Sheet Sizes: 49” x 97”, 61” x 145” (oversized by 1 inch) Fiberboard - Engineered wood product - Wood (poplar and softwoods) broken down into wood fibres using pressure and steam - Fibres formed into a continuous interfelted mat and compressed with rollers => Wetlaps - Continuous sheet cut into panels and then pressed 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes - Different amount of pressure, heat, and additives for different products: - LDF - Manufactured by cold pressing wetlaps in felted sheets - Held together by interlocking fibres rather than adhesive - Can contain additive such as fire retardant - Good sound absorption qualities - Standard thicknesses: ½” to 1” - Special order: 2” to 3” - Applications: - Ceiling tiles - Wall soundboards - Notice boards - MDF - Wetlaps include a binder - Wetlaps formed into panels under high temperature and pressure - Homogenous, flat, and smooth with a tempered surface - Allows for edge treatments and clean internal routings - Speciality types available - Same as particleboard - Applications: - Kitchen cabinet doors - Millwork/Mouldings - Core material for plywood - Slatwall - Commonly used for display purposes - Grades based on strength: 115, 130, and 155 - Names vary by supplier - Advantages: - Can be shaped due to uniform surface to core consistency - Often used for thermal foil doors or one piece CNC doors - Very smooth surface 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes - - - - HDF - - - Excellent for painted or coloured lacquer finish Disadvantages: - Edges can be problematic for finishing due to their porous nature - Prone to splitting when driving screws Joining: - Requires the same care as particleboard - Edge screws must be countersunk and have pilot holes drilled to prevent splitting - Will dull normal tools => Carbide cutters and tooling should be used Also known as “Hardboard” and “Masonite” Very durable thin sheets Typically has a very smooth tempered surface Available in: - Smooth back - Textured back - Perforated (pegboard) - Embossed (patterned) Numerous surface finishes and textures also available Common Thicknesses: ⅛”, 3/16”, ¼” - ⅛” commonly used for backs with “inset back construction” cabinets Grades: - Tempered: - Impregnated with resin and heat cured to improve… - Water resistance - Hardness - Strength - Finishing properties - Suitable for exterior applications as long as cut edges are sealed - Standard: 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes - - - - No special treatment after manufacturing - Used for cabinet back and drawer bottoms Service: - Lower strength - Rougher face - Used when lower quality is acceptable Oriented Strand Board - Not used in cabinet making - Manufactured by layering oriented wood strands and adhesive into mats - Mats compressed into panels under heat - Applications: - Plywood substitute for subfloors and sheathing - Core material for plywood - Panels are produced to specific densities, thickness tolerances, and surface finishes - Free of knots and voids - Often used as a core or substrate for overlays such as veneer, laminates, etc. Plywood - Any sheet product with outer plies made from veneer - Engineered sheet - 3 or more layers called plies - Minimum: - 2 outside plies of hardwood or softwood veneer - At least one core ply - Each core ply can be a sheet of veneer or layer of composite panel - Veneer Core: - Core comprised of layers of veneer - Core veneer is typically rotary sliced - Orientation of veneer plies is key to stability and strength - Crossbanding: - Process of alternating the grain direction of plies 90 degrees to adjacent plies - Any dimensional changes in plywood are equal in both directions 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes - - - - Labeled as “VC Plywood” - Performance affected by: - Thickness of each ply - Total number of plies - Adhesives: - Selected for intended environment (interior or exterior) - Particleboard Core - Veneer on each side - MDF core - Veneer on each side - Combination Core / Multi-core - Combination of composites and veneer for plies - Veneer in each side - Made to prevent the figure of the previous layer from telegraphing through the surface Always odd number of plies Face plies and core plies bonded together under high temp and pressure to form a plywood sheet Face and Back Plies: - Outside faces of a sheet - May or may not be the same species - Dependent on what will be visible in the application - Face ply often higher grade than back ply Hardwood Veneer Plywood Grades: - Grading defined by the Canadian HArdwood Plywood and Veneer Association - Face Veneer => Letter Grade (A, B, C) - Back Veneer => Number Grade (1, 2, 3) - End users must specify: - Core type (veneer, particleboard, mdf, combination) - Cut of veneer - Veneer match Baltic Birch Plywood: - Made from thin piles of birch - More plies than “normal” plywood - Very strong and dense - Available in many thicknesses: 3mm, 6mm, 9mm, 12mm, 18mm, 24mm 23F_WOO1410_01 Wood Technology Erik Rehm Test 3 Notes - - - Sheets are typically 60” x 60”, but some thicknesses also available in 4’ x 8’ - Edges often left untapped for an industrial look “Construction” Softwood Plywood Grades - Face, Inner Plies, and Back veneer => Letter Grade - Canadian Softwood Plywood Sizes: 48” x 96” - Thicknesses are metric - Available thicknesses differ between sanded and unsanded products Unlike particleboard and fiberboard, plywood is NOT OVERSIZED Handling and Storage of Panel Products: 1) 2) 3) 4) 5) 6) 7) Store sheets flat and level Do not store directly on concrete floors Protect panel edges and corners Carry panels on edge Do not slide sheets off a stack Ensure panels have acclimatized (adjusted climately) prior to use Protect from sunlight, water, and excessive humidity