Scribner vs. Cubic for Valuing Logs
Is there a clear choice?
Neal Hart, Jendro & Hart, LLC Timber Measurement Society Meeting, April 2019 Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991 1. Lumber Output to Log Input in Scribner & Cubic Log Scales 2. Return to Log Value $/Cunit: Lumber Output Scribner & Cubic Log Scales 3. Impact of Defect Deductions on Lumber Recovery Ratios & RTL Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
226 Test Logs • Length: 16’ • Diameter: 6” – 24” SED • Taper/16’: 1” – 4”, Ave 1.7” • Defect: Scribner 10% Cubic 7% Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
Number of Test Logs by Dia Class 25 20 15 10 5 0 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20+ Small Log Line Large Log Line Mfg Cost $/mbf lbr: 6”-8” $130.64 12”-15” $121.38 9”-11” $108.85 16”- 24” $120.89 Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
• ID number for each log Measured: Scribner board feet log scale Cubic feet product scale • Lumber tallied log by log Measured: Board feet lumber scale Cubic feet solid wood (finished) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991 Arden Log Test - Lumber Products and Average Selling Values Grade 1 x 4 1 x 6 1 x 8 1 x 12 2 x 4 2 x 6 2 x 8 2 x 10 2 x 12 #1 Dim 216 217 285 305 #2 Dim 216 217 285 305 #3 Dim 119 Lamstock 276 302 307 Stud Grade 118 115 STD & BTR 203 Utility 124 Economy 75 59 D & BTR 392 484 458 540 3 BTR COM 167 205 172 246 4 Common 131 114 99 57 5 Common 85 61 60 57 Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
Arden Sawmill Target Sizes Boards Green Finished Thickness: 1” = 0.940” 1” = 0.75” Widths: 4” = 4” 4” = 3.5” 6” = 5.875” 6” = 5.5” 8” = 7.875” 8” = 7.25” 12” = 11.875” 12” = 11.25” Dimension Thickness: 2” = 1.750” 2” = 1.50” Widths: 4” = 4” 4” = 3.5” 6” = 5.875” 6” = 5.5” 8” = 7.875” 8” = 7.25” 12” = 11.875” 12” = 11.25” For the purpose of this discussion:
Lumber Cubic ft of solid wood, CF or Cunits (100 CF)
Scribner bf / 12 = Cubic ft Logs of solid wood, CF or Cunits 1,200 bf Scribner = 1 Cunit Cubic is Cubic, CF or Cunits Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
Lumber Cubic ft / Gross Scribner Cubic ft 3.0
CF Lbr 2.5
2.0
1.5
1.0 Gross 0.5
Scribner 0.0 4 6 8 10 12 14 16 18 20 22 24 CF Log Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
Lumber Cubic ft / Net Scribner Cubic ft 3.0
CF Lbr 2.5
2.0
1.5
1.0
Net 0.5
Scribner 0.0 4 6 8 10 12 14 16 18 20 22 24 CF Log Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
Lumber Cubic ft / Log Cubic ft Gross 100% CF Lbr 90% 80% 70% 60% 50% 40% 30% 20% Gross 10% CF Log 0% 4 6 8 10 12 14 16 18 20 22 24 Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
Lumber Cubic ft / Log Cubic ft Net 100% CF Lbr 90% 80% 70% 60% 50% 40% 30% Net 20% 10% CF Log 0% 4 6 8 10 12 14 16 18 20 22 24 Log Diameter (small-end) Log Log #2 Return to Log Manufacturing Total log 7.2 cf Residuals 3.5 cf Lumber 3.7 cf
8 Top 10 Butt Douglas 30 Volume Gross Scribner Creek’sPlum Arden,WA Sawmill1991 10 Defect Scribner 20
$15.80 $14.30 Net Scribner ($8.00) Value $7.80 $1.50 7.2
Gross Cubic - fir 0.4 Defect Cubic - 6.8
Net Cubic Larch Log Test 2.0 2.0 2.0 1.0 1.0 1.0 1.0 Board Thick 6.0 6.0 6.0 4.0 4.0 4.0 4.0 Board Width 14 16 16 14 10 16 16 Board Length 18 22 22 22 C 2 2 Board Grade 64.6 14.0 16.0 16.0 4.7 3.3 5.3 5.3 Lumber bf Volume 14.30 3.02 4.83 3.46 0.78 0.43 0.89 0.89 Lumber Value $
3.7 0.8 0.9 0.9 0.3 0.2 0.3 0.3 Lumber Cubic Volume Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
Log #2 Alternative Volume Divisors to Calculate RTL $ per unit Lumber Scribner Cubic 100 CF Gross Net Net Gross Net Value (Cunits) MBF MBF Cunits Cunits Cunits Volume 0.037 0.030 0.020 0.0167 0.072 0.068 Total Rev $15.80 $427 $527 $790 $948 $219 $232 Mfg Cost $8.00 $216 $267 $400 $500 $111 $118 Return to Log $7.80 $211 $260 $390 $448 $108 $114 Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL Lumber CF ($/Cunit)__ 550
500 TL REV 450 400 LBR REV 350 300 RTL 250 200 150 6 - 8 9 - 13 14+ 100 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Correlation Coefficient Analysis Tool
RTL Lumber CF Compared Difference Between RTL to Hypothetical Log Scale Lumber CF & Hyp. Scale Corr. Coeff. 120 400 to Lbr RTL 350 100
300 80 Hyp. #1 250 Hyp. #1 60 (Const. (Const. Diff.) 200 Diff.) 40 1.000 150 20
100 0 50 6 8 10 12 14 16 18 20+ 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Correlation Coefficient Analysis Tool
RTL Lumber CF Compared Difference Between RTL to Hypothetical Log Scale Lumber CF & Hyp. Scale Corr. Coeff. 120 400 to Lbr RTL
350 Hyp. #1 100 Hyp. #2 (Const. (Incr. 300 Diff.) 80 Diff.) 1.000 250 60
200 40 Hyp. #1 Hyp. #2 (Const. 150 (Incr. Diff.) 20 Diff.) 100 0.987 0 50 6 8 10 12 14 16 18 20+ 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Correlation Coefficient Analysis Tool
RTL Lumber CF Compared Difference Between RTL to Hypothetical Log Scale Lumber CF & Hyp. Scale Corr. Coeff. 120 400 to Lbr RTL Hyp. #1 100 Hyp. #2 350 (Const. (Incr. Diff.) 80 Diff.) 300 1.000 60 Hyp. #1 250 Hyp. #2 40 (Const. (Incr. Diff.) Diff.) 200 20 0.987 0 Hyp. #3 150 (Random) Hyp. #3 -20 (Random) 6 8 10 12 14 16 18 20+ 100 -40 0.316 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL Lumber CF ($/Cunit)
400
350
300
250
200
150
100 6 - 8 9 - 13 14+ 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL Lumber CF vs. Scribner All Test Logs CF Lbr Corr. Coeff. 400 to Lbr RTL 350 Net Scribner
300 0.584
250
$/Cunit 200 Net 150 100 Scribner 6 - 8 9 - 13 14+ 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL Lumber CF vs. Scribner All Test Logs CF Lbr Corr. Coeff. 400 to Lbr RTL 350 Net Scribner
300 0.584
250
$/Cunit 200 8” Net 150 100 Scribner 6 - 8 9 - 13 14+ 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL Lumber CF vs. Scribner All Test Logs CF Lbr Corr. Coeff. 400 to Lbr RTL 350 Net Scribner
300 0.584
250
$/Cunit 200 9” Net 150 100 Scribner 6 - 8 9 - 13 14+ 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL Lumber CF vs. Scribner & Cubic All Test Logs CF Lbr Corr. Coeff. 400 to Lbr RTL 350 Net Scribner
300 0.584
250 Net Cubic Net $/Cunit 200 0.944 150
Scribner 100 6 - 8 9 - 13 14+ & Cubic 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL Lumber CF vs. Scribner & Cubic All Test Logs CF Lbr Corr. Coeff. 400 to Lbr RTL 350 Net Scribner
300 0.584
250 Net Cubic Net $/Cunit 200 0.944 150
Scribner 100 6 - 8 9 - 13 14+ & Cubic 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL Lumber CF vs. Scribner & Cubic All Test Logs CF Lbr Corr. Coeff. 400 to Lbr RTL 350 Net Scribner
300 0.584
250 Net Cubic $/Cunit Net 200 0.944 150
Scribner 100 6 - 8 9 - 13 14+ & Cubic 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL Lumber CF vs. Scribner All Test Logs CF Lbr Corr. Coeff. 400 to Lbr RTL 350 Net Scribner
300 0.584
250 Net Cubic Net $/Cunit 200 0.944 150 Gross Cubic Scribner 100 6 - 8 9 - 13 14+ 0.977 & Cubic 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
Impact of Defect on Scribner vs. Cubic RTL? Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991 RTL CF Lumber - All Test Logs vs.
Scribner & Cubic RTL for Logs Corr. Coeff. to With Defect (92) & W-No Defect (134)_ CF Lbr 550 Lbr RTL All Logs 500 450 400
350 Net Scrib No Def
$/Cunit 300 0.555 Net 250 200 Scribner 150 100 6 - 8 9 - 13 14+ & Cubic 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991 RTL CF Lumber - All Test Logs vs.
Scribner & Cubic RTL for Logs Corr. Coeff. to With Defect (92) & W-No Defect (134)_ CF Lbr 550 Lbr RTL All Logs 500
450 Net Scrib W-Def 400 0.000 350 Net Scrib No Def
$/Cunit 300 Net 250 0.555 200 Scribner 150 100 6 - 8 9 - 13 14+ & Cubic 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
Impact of Defect on Gross Scribner & Cubic Recovery Ratios _ (CF Lumber / CF Gross Log Scale) 2.1 CF Lbr 1.9 1.7 1.5 1.3 No Def Scrib 1.1 Gross Gross Def Scrib 0.9 Gross Scribner No Def Gross 0.7 Cubic 0.5 Def Gross & Cubic Cubic 0.3 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991 Impact of Defect on Net Scribner & Cubic Recovery Ratios _ (CF Lumber / CF Net Log Scale) 2.1 1.9 Defect Deduction Excessive CF Lbr esp. in smaller diameters 1.7 1.5 1.3 Def Scrib Net 1.1 Net No Def Scrib 0.9 Net Scribner Def Net 0.7 Cubic 0.5 No Def Net & Cubic Cubic 0.3 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991 Scribner vs. Cubic Ave % Defect Deduction by Diameter _ 20% 6”-13” 14”+ Scribner Cubic Scribner Cubic Scribner 15% 8% 4% 11% 8% Defect
10%
Cubic 5% Defect
0% 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991 RTL CF Lumber - All Test Logs vs.
Scribner & Cubic RTL for Logs Corr. Coeff. to With Defect (92) & W-No Defect (134)_ CF Lbr 550 Lbr RTL All Logs 500
450 Net Scrib W-Def 400 0.000 350 Net Scrib No Def
$/Cunit 300 Net 250 0.555 200 Scribner 150 100 6 - 8 9 - 13 14+ & Cubic 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991 RTL CF Lumber - All Test Logs vs.
Scribner & Cubic RTL for Logs Corr. Coeff. to With Defect (92) & W-No Defect (134)_ CF Lbr 550 Lbr RTL All Logs 500 Net Scrib W-Def 450 0.000 400 Net Scrib No Def 350
$/Cunit 300 0.555 Net 250 Net Cubic W-Def 200 0.766 Scribner 150 100 Gross Cubic W-Def 6 - 8 9 - 13 14+ & Cubic 50 0.765 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991 RTL CF Lumber - All Test Logs vs.
Scribner & Cubic RTL for Logs Corr. Coeff. to With Defect (92) & W-No Defect (134)_ 550 Lbr RTL All Logs CF Lbr Net Scrib W-Def 500 0.000 450 Net Scrib No Def 400 0.555 350 Net Cubic W-Def
$/Cunit 300 0.766 250 Net Gross Cubic W-Def 200 Scribner 150 0.765 Net & Gross Cubic 100 & Cubic 6 - 8 9 - 13 14+ No Def 50 0.894 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL - Lumber CF vs. Net Scribner & Cubic _ All Test Logs 400 CF Lbr 6 - 7 8 - 12 13+ 350 Net Scribner 300
250
$/Cunit Net Cubic Net 200 150
Scribner100 6 - 8 9 - 13 14+ & Cubic 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL - Lumber CF vs. Net Scribner & Cubic _ All Test Logs 400 CF Lbr 6 - 7 8 - 12 13+ 350 Net Scribner 300
250
Net Cubic $/Cunit Net 200 150 Dia Class Scribner100 Ave 6 - 8 9 - 13 14+ & Cubic 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
RTL - Lumber CF vs. Net Scribner & Cubic _ All Test Logs 400 CF Lbr 6 - 7 8 - 12 13+ 350 Net $362 Scribner $262 $338 300
250 Net
$/Cunit Cubic 200 $181 Net $155 Break-Even 150 $107 Log Price: Dia Class Scribner100 Ave 6 - 8 9 - 13 14+ & Cubic 50 6 8 10 12 14 16 18 20+ Log Diameter (small-end) Douglas-fir-Larch Log Test Plum Creek’s Arden, WA Sawmill 1991
Difference Between Log Price & Sawmill RTL CF Lbr Net Scribner Net Cubic Dia W- No W- No Class Defect Defect Defect Defect 6”- 7” -10.8% +3.0% -5.0% +3.1% Difference: 13.8% 8.1% Net 8”- 13” -5.6% +6.5% -0.6% -0.7% Scribner Difference: 12.1% 0.1% & Cubic 14”+ 0.0% +1.3% -1.1% +0.9% Difference: 1.3% 2.0% Scribner vs. Cubic for Valuing Logs ?
Cubic, esp. for Logs < 14”: • Tracks better w-lumber RTL • Logical progression of value • Better accounts for defect Questions?
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