P17 - Board Foot Calculations - Rev 23A.pdf

Board-Foot Calculations 1 Volume • Volume – The amount of space that a substance or object occupies volume = length x width x height v =lxwxh – Units • • • • • cubic foot: ft3 or cuft cubic inches: in3 cubic meter: m3 cubic centimeter: cm3 Board Foot: BdFt 2 1 Board Foot • A measure of volume...

Board-Foot Calculations 1 Volume • Volume – The amount of space that a substance or object occupies volume = length x width x height v =lxwxh – Units • • • • • cubic foot: ft3 or cuft cubic inches: in3 cubic meter: m3 cubic centimeter: cm3 Board Foot: BdFt 2 1 Board Foot • A measure of volume • BdFt • 1 BdFt = 144 cubic inches 12” x 12” x 1” = 144 cubic inches = 1 board foot 24” x 6” x 1” = 144 cubic inches = 1 board foot 12” x 6” x 2” = 144 cubic inches = 1 board foot 3 Board Feet To determine the number of Board Feet, divide the volume in cubic inches by 144 𝑉𝑜𝑙𝑢𝑚𝑒 𝐵𝑑𝐹𝑡 = 𝑉𝑜𝑙𝑢𝑚𝑒 𝑖𝑛 𝐶𝑢𝑏𝑖𝑐 𝐼𝑛𝑐ℎ𝑒𝑠 144 4 2 How many Board Feet? 96” long x 6” wide x 1” thick 96” long x 12” wide x 2” thick 12’ long x 8-1/2” wide x 1” thick 5 Why do we care about Board Feet? 6 3 Cut List • List of material required for a project • Includes Quantity, Dimensions, and Material for each board T CUT LIS https://s-media-cacheak0.pinimg.com/236x/fa/f1/a3/faf1a3eac1d 1c0e592f48686e29651c6.jpg 7 Cut List Format for Size and Quantity 2@ 89” x 14” x Quantity Grain Direction Cross-Grain Direction 1” Thickness Why use a standard format? How many BdFt? 8 4 What is the Cut List Entry for this Board? 15” ¾” 12” Not To Scale 9 What is the Cut List Entry for this Board? 12” ¾” 15” Not To Scale 10 5 Rough Sawn Lumber vs Surfaced Lumber • Rough sawn lumber – Cut – Dried • Surfaced Lumber http://woodshedlumber.com/img/products/rough-sawn-lumber.jpg Most cabinetmakers purchase rough lumber and surface it as required – “Dressed Lumber” – Rough sawn lumber that has been jointed and planed to create smooth surfaces – The jointing and planing process makes the board thinner http://www.weaberlumber.com/images/slideshow/s4s1.jpg 11 Rough Lumber Thickness • Stated in “quarters” • “nominal” thickness before drying • Not all thicknesses will be available from all suppliers • Not all thicknesses will be available in all species http://www.popularwoodworking.com/wpcontent/uploads/buy-use-rough-lumber_5F00_start-outthick1.jpg 12 6 http://www.wood-source.com/ 13 http://www.wood-source.com/ 14 7 http://www.wood-source.com/ 15 http://www.wood-source.com/ 16 8 http://www.wood-source.com/ 17 Surfacing (Dressing) Lumber • 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 1/8” 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 18 9 • Assume that 4/4, 5/4, 6/4, 8/4, 12/4 lumber is available at your supplier • For each of the following surfaced lumber thicknesses, what thickness of rough lumber should be purchased • • • • 1/2” 3/4” 7/8” 1” • • • • 1-1/4” 1-1/2” 1-3/4” 2” • • • • 2-1/4” 2-1/2” 2-3/4” 3” 19 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 20 10 Wastage • Unable to use 100% of lumber purchased – FAS has a yield of 83% à 17% wastage – Select has a yield of 83% à 17% wastage – No. 1 Common has yield of 67% à 33% wastage • Also – 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 Assume 25% for the practice exercises unless otherwise stated 21 Dressed Lumber Requirement = 8 @ 62” x 15 ¼” x ¾” How many Board Feet of rough lumber should be purchased? (4/4 and 5/4 lumber is available) Board Foot Calculation: Thicker rough lumber purchased to accommodate surfacing 4 ” = 8 @ 62” × 15.25”× 1” = 8 @ 945.5 𝑐𝑢 𝑖𝑛 4 = 8 × 945.5 𝑐𝑢 𝑖𝑛 = 7,564 𝑐𝑢 𝑖𝑛 8 @ 62” × 15.25”× Convert to BdFt à 7,564 𝑐𝑢 𝑖𝑛 = 52.52778 𝐵𝑑𝐹𝑡 144 𝑐𝑢 𝑖𝑛 𝑝𝑒𝑟 𝐵𝑑𝐹𝑡 Apply Shrinkage Factor (7%) à 52.52778 × 1.07 = 56. 20472 𝐵𝑑𝐹𝑡 Apply Wastage Factor (25%) à 56. 20472 × 1.25 = 70. 25590 𝐵𝑑𝐹𝑡 Round UP to the next whole BdFt à 71 BdFt 71 BdFt of rough lumber should be purchased. 22 11 IMPORTANT Applying a 7% factor and then applying a 25% factor IS NOT the same as applying a 32% factor 7% + 25% = 32% 100 × 1.07 = 107 100 × 1.32 = 132 107 × 1.25 = 133.75 When performing Board Foot Calculations, apply the shrinkage factor and then apply the wastage factor 23 BdFt Calculations with Multiple Boards 1. Determine rough lumber thickness for each board size 2. Group Boards with the same rough lumber thickness together 3. For each unique rough lumber thickness: 1. Determine volume (cubic inches) for each board size and multiply by the quantity of boards at that specific size… leave answer in cubic inches 2. Add volume of all boards with the same rough lumber thickness together à total volume in cubic inches 3. Convert total cubic inches into Board Feet 4. Apply Shrinkage factor (1.07 unless otherwise specified) 5. Apply Wastage Factor (1.25 unless otherwise specified) 6. Round up to nearest whole BdFt value 24 12 How Much Rough Lumber Should be Purchased? Dressed lumber requirements: 4 @ 48” x 6 ¾” x 1 ¾” 6 @ 84” x 5 ¼” x ¾” 2 @ 31” x 10” x ½” 4/4, 5/4, 6/4, 8/4, 12/4 rough lumber available Assume a wastage factor of 30% 25 4! , 5! , 6! , 8! , 12! 𝑟𝑜𝑢𝑔ℎ 𝑙𝑢𝑚𝑏𝑒𝑟 𝑎𝑣𝑎𝑖𝑙𝑎𝑏𝑙𝑒 4 4 4 4 4 𝑠𝑒𝑙𝑒𝑐𝑡 𝑟𝑜𝑢𝑔ℎ 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 4 @ 48”×6 ¾”×1 ¾” → 4 @ 48”×6 ¾”× 𝟒𝟖” = 4 × 48” ×6.75” × 2” = 2,592 𝑐𝑢 𝑖𝑛 6 @ 84”× 5 ¼”× ¾” → 6 @ 84”× 5 ¼”× 𝟒𝟒” = 6 × 84” ×5.25” × 1” = 2,646 𝑐𝑢 𝑖𝑛 2 @ 31”× 10”× ½” → 2 @ 31”× 10”× 𝟒𝟒” = 2 × 31” × 10” × 1” = 620 𝑐𝑢 𝑖𝑛 𝑇𝑜𝑡𝑎𝑙 𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝟒!𝟒 𝑙𝑢𝑚𝑏𝑒𝑟 𝑖𝑛 𝑐𝑢 𝑖𝑛 = 2,646 + 620 𝑐𝑢 𝑖𝑛 = 3,266 𝑐𝑢 𝑖𝑛 𝑇𝑜𝑡𝑎𝑙 𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝟖!𝟒 𝑙𝑢𝑚𝑏𝑒𝑟 𝑖𝑛 𝑐𝑢 𝑖𝑛 = 2,592 𝑐𝑢 𝑖𝑛 𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝟖!𝟒 𝑙𝑢𝑚𝑏𝑒𝑟 𝑖𝑛 𝐵𝑑𝐹𝑡 2,592 = = 18.0000 𝐵𝑑𝐹𝑡 144 𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝟒!𝟒 𝑙𝑢𝑚𝑏𝑒𝑟 𝑖𝑛 𝐵𝑑𝐹𝑡 3,266 = = 22.6806 𝐵𝑑𝐹𝑡 144 22.68 ×1.07 = 24.2682 𝐵𝑑𝐹𝑡 𝐴𝑝𝑝𝑙𝑦 7% 𝑠ℎ𝑟𝑖𝑛𝑘𝑎𝑔𝑒 𝑓𝑎𝑐𝑡𝑜𝑟 18.00 ×1.07 = 19.2600 𝐵𝑑𝐹𝑡 24.2682 × 1.30 = 31.5487 𝐵𝑑𝐹𝑡 𝐴𝑝𝑝𝑙𝑦 30% 𝑤𝑎𝑠𝑡𝑎𝑔𝑒 𝑓𝑎𝑐𝑡𝑜𝑟 19.2600 × 1.30 = 25.0380 𝐵𝑑𝐹𝑡 𝑄𝑢𝑎𝑛𝑡𝑖𝑡𝑦 𝑜𝑓 𝟒!𝟒 𝑙𝑢𝑚𝑏𝑒𝑟 = 32 𝐵𝑑𝐹𝑡 𝑅𝑜𝑢𝑛𝑑 𝑢𝑝 𝑡𝑜 𝑛𝑒𝑥𝑡 𝑤ℎ𝑜𝑙𝑒 𝐵𝑑𝐹𝑡 𝑄𝑢𝑎𝑛𝑡𝑖𝑡𝑦 𝑜𝑓 𝟖!𝟒 𝑙𝑢𝑚𝑏𝑒𝑟 = 26 𝐵𝑑𝐹𝑡 26 13 Questions? 27 14