SawmillSawmill ShortShort CourseCourse LogLog InputsInputs –– MeasurementMeasurement && ConversionConversion FactorsFactors Dr.Dr. KurtKurt MackesMackes AssistantAssistant ProfessorProfessor DepartmentDepartment ofof Forest,Forest, Rangeland,Rangeland, andand WatershedWatershed StewardshipStewardship ColoradoColorado StateState UniversityUniversity TopicsTopics toto bebe discusseddiscussed 1.1. CommonCommon loglog measurementsmeasurements 2.2. ScalingScaling logslogs 3.3. ConversionConversion factorsfactors forfor loglog andand lumberlumber measurementsmeasurements 4.4. ValueValue addedadded opportunitiesopportunities inin gradinggrading lumberlumber CommonCommon LogLog MeasurementsMeasurements ¾ BoardBoard FootFoot ¾ CubicCubic footfoot ¾ StackedStacked (Cords)(Cords) ¾ LinearLinear footfoot ¾ WeightWeight BoardBoard FootFoot ¾ DefinedDefined asas aa boardboard containingcontaining 144144 cubiccubic inchesinches ofof sawedsawed lumberlumber oror thethe equivalentequivalent ofof aa boardboard 1212 inchesinches long,long, 1212 inchesinches wide,wide, andand 11 inchinch thickthick BoardBoard footagefootage calculationcalculation (lumber)(lumber) • Softwood lumber: Use nominal dimensions • Hardwood lumber: Use nominal thickness and actual width CubicCubic FootFoot ofof WoodWood ¾ DefinedDefined asas aa solidsolid piecepiece ofof woodwood thatthat isis 11 footfoot long,long, 11 footfoot wide,wide, andand 11 footfoot thickthick • This unit is considered the most accurate in common use • Does not allow for sawkerf, slabs edgings, shrinkage, bark, or sawing method • Pulpwood and salvage materials often measured in cubic feet or cunits (100 cubic feet) CordsCords ¾ DefinedDefined asas aa stackstack ofof woodwood thatthat occupiesoccupies aa volumevolume ofof 128128 cubiccubic feetfeet ForFor example,example, aa pilepile ofof woodwood 44 feetfeet talltall byby 44 feetfeet byby 88 feetfeet longlong isis oneone cordcord AA pilepile ofof woodwood thatthat occupioccupieses 160160 cubiccubic feetfeet isis calledcalled aa longlong cordcord LinearLinear FootFoot ofof WoodWood ¾ AA woodwood membermember oror loglog ofof variablevariable widthwidth andand thicknessthickness thatthat isis oneone footfoot inin lengthlength ForFor example,example, slabsslabs (both(both edgededged andand unedgedunedged)) areare oftenoften soldsold byby thethe linearlinear footfoot WoodWood WeightWeight UsuallyUsually measuredmeasured inin tonstons ¾ Weigh truck empty and fully loaded, subtracting weight of truck from gross (loaded) weight. ¾ Pulpwood, southern yellow pine logs, and some hardwood logs (chipwood) ScalingScaling LogsLogs ¾ BoardBoard footfoot loglog rulesrules ¾ CubicCubic footfoot scalingscaling ¾ WeightWeight scalingscaling BoardBoard FootFoot LogLog RulesRules ¾ TheThe threethree mostmost commonlycommonly usedused boardboard footfoot loglog rulesrules are:are: 1. ScribnerScribner DecimalDecimal CC 2. InternationalInternational (saw(saw kerfkerf ¼¼ inch)inch) 3. DoyleDoyle • The International Rule is most precise, but the Scribner Decimal C is more commonly used • In the Rocky Mountain Region, Doyle’s log rule is only used in eastern Kansas and Nebraska LogLog ScalingScaling AssumptionsAssumptions ¾ TheThe loglog isis aa cylindercylinder • Cylinder diameter equals inside bark diameter at the small end of log • Cylinder length equals log length ¾ LogsLogs areare cutcut intointo boardsboards oneone inchinch thickthick ¾ SawSaw bladeblade thicknessthickness ((kerfkerf)) variesvaries fromfrom 1/81/8 toto 3/83/8 inchesinches ¾ BoardsBoards areare utilizedutilized toto thethe specifiedspecified minimumminimum widthwidth ¾ TheThe minimumminimum boardboard lengthlength equalsequals loglog lengthlength ¾ TheThe loglog ifif freefree ofof defectsdefects LogLog RulesRules –– StepStep FunctionsFunctions MerchantabilityMerchantability GuidelinesGuidelines GuidelinesGuidelines varyvary byby region:region: ¾ TheThe minimumminimum merchantablemerchantable lengthlength isis 66 feet,feet, butbut thethe minimumminimum cancan varyvary fromfrom 66 toto 1616 feetfeet ¾ MinimumMinimum smallsmall endend diameterdiameter isis usuallyusually 55 toto 88 inchesinches ¾ MinimumMinimum percentagepercentage ofof grossgross scalescale remainingremaining afterafter scalingscaling isis 33%33% forfor valuablevaluable coniferousconiferous andand 50%50% forfor lessless valuablevaluable speciesspecies DefectDefect DeductionsDeductions DefectDefect types:types: • MechanicalMechanical • BiologicalBiological • PhysicalPhysical DefectDefect ClassificationsClassifications (Region(Region 2)2) 1.1. InteriorInterior defectsdefects 2.2. SideSide defectsdefects 3.3. DefectsDefects fromfrom curvecurve andand sweepsweep 4.4. DefectsDefects fromfrom crotchescrotches 5.5. DefectsDefects fromfrom excessiveexcessive knotsknots MethodsMethods ofof EstimatingEstimating DefectDefect DeductionsDeductions FourFour mainmain methods:methods: 1. SquaredSquared defectdefect 2. PiePie--cutcut 3. LengthLength deductiondeduction 4. DiameterDiameter deductiondeduction SquaredSquared DefectDefect MethodMethod ¾ DefectiveDefective areaarea enclosedenclosed inin aa squaresquare ¾ ForFor ScribnerScribner DecimalDecimal C:C: D = W” x H” x L’ 15 Where:W = Width of defect in inches (plus 1” for waste) H = Height of defect in inches (plus 1” for waste) L = Length of defect D = Deduction in board fee ¾ CommonlyCommonly usedused forfor internalinternal defectsdefects suchsuch asas rotsrots andand heartheart checkschecks PiePie--cutcut MethodMethod ¾ Used when a defect is deep and pie shaped, contained within a sector of a circle ¾ The deduction has the same relationship to total scale as the sector does to the circle ¾ Deduction estimates of 1/8, 1/4, 1/3, 1/2, or 2/3 are used ¾ Defects that this method applies well to include catfaces, fire scars, grubworm holes, and rotton knots LengthLength DeductionDeduction MethodMethod ¾ UsedUsed whenwhen defectsdefects resultresult inin lumberlumber shortershorter thanthan loglog lengthlength ¾ ItIt shouldshould bebe usedused whenwhen thethe deductiondeduction forfor squaredsquared defectdefect exceedsexceeds thethe scalescale ofof thethe loglog lengthlength ¾ SuchSuch defectsdefects maymay includeinclude sweep,sweep, firefire scar,scar, knotknot clusters,clusters, largelarge burls,burls, breaks,breaks, crotches,crotches, massedmassed pitch,pitch, andand rotrot DiameterDiameter DeductionDeduction ¾ InvolvesInvolves reducingreducing thethe scalingscaling diameterdiameter ofof thethe loglog ¾ ItIt isis usedused forfor defectsdefects suchsuch asas sapsap rot,rot, weatherweather checks,checks, shallowshallow catcat faces,faces, perimeterperimeter rings,rings, andand excessiveexcessive knotsknots ¾ Example:Example: AA loglog withwith sapsap rotrot measuresmeasures 12”12” inin diameter.diameter. TheThe rottenrotten sapwoodsapwood isis 1”1” thick.thick. TheThe grossgross diameterdiameter ofof thethe loglog isis decreaseddecreased byby 2”,2”, withwith aa netnet diameterdiameter andand scalescale ofof aa 10”10” diameterdiameter log.log. BuckingBucking LogsLogs forfor ScaleScale (Value)(Value) BuckingBucking objectives:objectives: ¾ CutCut logslogs toto millmill specificationsspecifications ¾ MaximizeMaximize valuevalue ofof logslogs cutcut fromfrom stemstem ¾ MinimizeMinimize wastewaste TheThe EffectEffect ofof BuckingBucking DecisionsDecisions onon LogLog ScaleScale (Volume)(Volume) 33” 13” Gross Volume (Scribner) = 2290 Board feet 33” 27” 13” Gross Volume (Scribner) = 3300 Board feet CubicCubic FootFoot MeasureMeasure ¾ CubicCubic footfoot rulesrules areare basedbased onon formulaeformulae ¾ TheThe loglog isis considerconsider toto bebe aa cylindercylinder havinghaving aa scalingscaling diameterdiameter equalequal toto thethe diameterdiameter insideinside barkbark atat thethe loglog centercenter ¾ LogLog volumevolume isis equalequal toto thethe basalbasal areaarea inin squaresquare feetfeet atat thethe log’slog’s centercenter multipliedmultiplied thethe loglog lengthlength ¾ CommonCommon cubiccubic footfoot rulesrules are:are: • Smalian Rule • Two-end Conic Rule • Sub-Neiloid Rule SmalianSmalian RuleRule ¾ TheThe averageaverage basalbasal areaarea isis estimatedestimated byby measuringmeasuring diameterdiameter insideinside barkbark atat bothboth loglog ends,ends, computingcomputing basalbasal areaarea forfor bothboth diameters,diameters, andand thenthen multiplyingmultiplying thethe averageaverage ofof thethe twotwo basalbasal areasareas byby thethe loglog lengthlength Cubic foot volume = (Small end BA + Large end BA) x Log length 2 TwoTwo--endend ConicConic RuleRule ¾ TheThe loglog isis consideredconsidered toto bebe aa frustrumfrustrum ofof aa conecone Cubic foot volume = 0.005454L x [D2(SE) + D2(LE) + D(SE) + D(LE] 3 ¾ RelativelyRelatively newnew rulerule provprovidedided asas anan optionoption byby thethe ColumbiaColumbia RiverRiver LogLog ScalingScaling andand GradingGrading BureauBureau SubSub--NeiloidNeiloid RuleRule ¾ UsedUsed wherewhere logslogs toto bebe scaledscaled havehave aa shapeshape thatthat moremore closelyclosely approachesapproaches thethe frustrumfrustrum ofof aa neiloidneiloid Cubic foot volume = 0.005454L x [D(SE) + D(LE]2 2 ¾ ThisThis rulerule hashas beenbeen usedused onon aa moremore limitedlimited basisbasis IsIs therethere aa bestbest system?system? –– TheThe casecase forfor usingusing cubiccubic volumevolume ¾¾ ChangeChange inin length/changelength/change inin volumevolume criteriacriteria ¾¾ AbilityAbility toto accountaccount forfor secondarysecondary productsproducts