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Wood 120 – Lumber Volume Lab #1 - 2011 1

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2 Lumber volume In sawmilling, lumber is most often measured by the “board foot” or “fbm” (Foot Board Measure). 1fbm = 1 foot x 1 foot x 1 inch A thousand fbm is written “Mfbm” A million fbm is written as “MMfbm”

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Robert Fürst – Wood 120 Log Scaling in Cubic Logs in BC are usually measure in cubic meters Smalian’s Formula is the standard used in BC

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Robert Fürst – Wood 120 Smalian’s Formula AbAb AuAu h Vol = h/2 (Ab + Au) Where: H = Height Ab = cross section area at base Au = cross section are at top Area (A b or A u )=(d² x 3.14)/4

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Robert Fürst – Wood 120 Excel Example Area (Ab or Au)=(d² x 3.14)/4

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6 Foot Board Measure 12 inches 1 inch Board foot = 12 inches wide, 12 inches long, 1 inch thick = 1/12 ft 3

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7 Largest sawmill production capacity 600 MMfbm (Houston, BC) Average BC sawmill capacity approx. 150-200 MMfbm Price of softwood lumber $250-275/Mfbm Price of hardwood lumber e.g. sugar maple $4/board foot

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Robert Fürst – Wood 120 Quick conversion factors Millimeters to Inches multiply by 0.03937 Inches to Millimeters multiply by 25.4 Meters to Feet multiply by 3,281 Feed to Metersmultiply by 0.3048 Square Meters to Square feet multiply by 10.764 Square Feet to Square Meters multiply by 0.0929 Cubic Meters to Board Footage multiply by 423.79 Board footage to Cubic Metersmultiply by 0.0023596

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Robert Fürst – Wood 120 Volume of lumber - Conversion When calculating board footage from metric sizes, it is necessary to convert the metric size to imperial measure before you begin the calculation Example: 10 pieces - 27mm thick - 105mm wide - 3 meter long 1 mm = 0.039937 in, ; 1 meter = 3.281 ft. 10 pieces x 27 x 0.03937 x 105 x 0.03937 x 3 x 3.281 12 = 36 board feet

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10 Lumber Recovery Factor (LRF) Definition: LRF is how many board feet of green/rough sawn lumber are produced out of one cubic meter of wood. The units of LRF are board feet per cubic meter. LRF typically ranges between 200 to 300 board feet per cubic meter.

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11 Lumber Recovery Factor (LRF) LRF depends on: Size of logs entering the mill Quality of log – defects, grade Equipment used in a mill 50 55 60 65 70 75 Recovery % 212 233 254 275 296 318 FBM/m 3

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12 British Columbia Sawmill Lumber Recovery Factors BC Mills +17% Leading Mills Average LRF (bf/m ) 3 231 271 (BC MoF, 2005)

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13 Standard Thicknesses Nominal size (in inches) 246810 1.53.55.57.259.25 Actual size (in inches)

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14 Target Thickness Minimum dimension required to achieve desired final size given unavoidable reductions in size during manufacture.

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Robert Fürst – Wood 120 Fibre Recovery - Percentage Finished lumber (kds4s) 47% Chips 34% Sawdust & chip fines 9% Shrinkage 4% Shavings 6%

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Robert Fürst – Wood 120 Lab Assignment Sawing – LRF – Log Volume

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Robert Fürst – Wood 120 Lab Tasks - Sawing Calculate the log volume of the sample log (m3) Make 2 horizontal reference cuts #1 #2

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Robert Fürst – Wood 120 Lab Task - Sawing Rotate log 90°, cut reference cut, saw boards #3 #4

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Robert Fürst – Wood 120 Lab Task - Sawing Cut the log into 2” thick boards

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Robert Fürst – Wood 120 Lab Tasks - Sawing Rip each individual board to 4” wide components Grade each board (No wane, no loose knots, no end splits longer than 2”, no center board) Calculate the volume (in bf) of the 2/4 material recovered Calculate the LRF in % Wane

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Robert Fürst – Wood 120 Document your findings of the lab Write a brief report describing all of your findings of the lab and explain what caused the fairly low LRF. Please be specific! Submit all of your calculations as required Due date: Group 1: 1st December 2011 Group 2: 8th December 2011 Please e-mail your report to Max Cosen E-Mail: mclosen@interchange.ubc.camclosen@interchange.ubc.ca

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