wood 120 – lumber volume
DESCRIPTION
Wood 120 – Lumber Volume. Lab #1 - 2013. 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”. Log Scaling in Cubic. - PowerPoint PPT PresentationTRANSCRIPT
Wood 120 – Lumber Volume
Lab #1 - 2013
1
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”
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
Robert Fürst – Wood 120
Smalian’s Formula
Ab
Au
h
Vol = h/2 (Ab + Au)
Where:
H = Height
Ab = cross section area at base
Au = cross section are at top
Area (Ab or Au)=(d² x 3.14)/4
Robert Fürst – Wood 120
Excel Example
sed 7.0 inches 17.8 cmled 9.0 inches 22.9 cmlength 16.0 feet 4.9 meters
Ab 0.2673 ft2 0.0248 m2
Au 0.4418 ft2 0.0410 m2
Vol 5.67 ft3 0.1606 m3
Imperial Metric
Log Volume Estimation using Smalian's Formula
Area (Ab or Au)=(d² x 3.14)/4
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Foot Board Measure
12 inches12
inch
es
1 inch
Board foot = 12 inches wide, 12 inches long, 1 inch thick
= 1/12 ft3
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• Largest sawmill production capacity600 MMfbm (Houston, BC)
• Average BC sawmill capacityapprox. 150-200 MMfbm
• Price of softwood lumber
$250-275/Mfbm
• Price of hardwood lumbere.g. sugar maple $4/board foot
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 Meters multiply 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 Meters multiply by 0.0023596
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 3.28112
= 36 board feet
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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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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 75Recovery %
212
233
254
275
296
318
FBM/m3
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British Columbia Sawmill British Columbia Sawmill Lumber Recovery FactorsLumber Recovery Factors
200
220
240
260
280
300
320
1990 1992 1994 1996 1998 2000 2002 2004
Years
BC Mills +17%
Leading Mills
Ave
rag
e L
RF
(b
f/m
)
3
231
271
(BC MoF, 2005)(BC MoF, 2005)
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Standard Thicknesses
Nominal size (in inches)
2 4 6 8 10
1.5 3.5 5.5 7.25 9.25
Actual size (in inches)
14
Target ThicknessMinimum dimension required to achieve desired final size given unavoidable reductions in size during manufacture.
Robert Fürst – Wood 120
Fibre Recovery - Percentage
Finished lumber (kds4s) 47%Chips 34%Sawdust & chip fines 9%Shrinkage 4%Shavings 6%
Robert Fürst – Wood 120
Lab Assignment Sawing – LRF – Log Volume
Robert Fürst – Wood 120
Lab Tasks - Sawing
• Calculate the log volume of the sample log (m3)
• Make 2 horizontal reference cuts
#1 #2
Robert Fürst – Wood 120
Lab Task - Sawing
• Rotate log 90°, cut reference cut, saw boards
#3 #4
Robert Fürst – Wood 120
Lab Task - Sawing
• Cut the log into 2” thick boards
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
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: 28th November 2013• Group 2: 5th December 2013 • Please e-mail your report to Mr. Sheng Xie
E-Mail: [email protected]