By ketmd F. Hanks Gtenra La Gammon Roblea L. Srisbin Evereee El. RasZ HARDWOOD LOG GRADES and Lumber Grade Yields for ~actorL Lumber Logs FOREST SERVICE RESEARCH PAPER ME-468 1980 FOREST SERVICE, U.S. DEPARTMENT QF AGRICULTURE NORTHEASTERN FOREST EXPERIMENT STATION 370 REED WOAD, BROOMALL, PA f %208
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By ketmd F. Hanks Gtenra La Gammon Roblea L. Srisbin Evereee El. RasZ
HARDWOOD LOG GRADES and Lumber Grade Yields for ~actorL Lumber Logs
FOREST SERVICE RESEARCH PAPER ME-468 1980
FOREST SERVICE, U.S. DEPARTMENT QF AGRICULTURE NORTHEASTERN FOREST EXPERIMENT STATION
370 REED WOAD, BROOMALL, PA f %208
The Authors
LELAND F. HANKS received B.S. and M.S. degrees from Iowa State University. Me is presently employed by the Eastern Region of the USDA Forest Service, having spent 1 8 years with the Qntral States and North. eastern Forest Experiment Stations.
GLENN L. GMMON, fomerly a research forest products technologist with the Northeastern Forest Experiment Station at &laware, Qhio, received a B.S. degree in forestry from the Unitrersity of Georgia and an M.S. degree in wood technology from the University of New H a p - shire.
ROBERT L. BRISBIN, research forest products technologist, received a B.S. degree in forestry from Iowa State University in 1961 and an M.S. degree in wood technology from the Pennsylvania State University in 1969. IIe joined the Northeastem Forest Experiment Station in 1961, and is now leader of the quality and pade of hardwood timber project at Delaware, Ohio.
EVERE'FTE D. RAST, research forest products technologist, received a B.S. degree in forestry from the University of Missouri in 1960 and an M.S. degree in agricultural economics from Ohio State University in 1970. He joined the Forest Service in 1960 as a forester on the Mendocino National Forest, transferring to the Nodheastern Forest Experiment Station at Deiaware in 1966.
MANUSCRLPT RECEIVED FOR PUBLICATION 14 AUGUST 1980
Abstract
Tho USDA Forest Service Standard Grades for Hardwood Factory Lumber Logs are described, and lumber pade yields for 1 6 species and 2 species groups are presented by log grade and log diameter. The grades enable foresters, log buyers, and log sellers to select and grade those Iogs suitable for conversion into standard factory grade lumber. By using the appropxiak lumber grade yields, log buyers and sellers can appraise the logs in terms of expected lumber grade volume and value. This report supersedes an earlier report an hardwood log grading, Forest Service Research Paper FPL 63.
AWC'MILL OPERATORS learned !ong ago "J that small, knotty logs are less valuable
than large, clear ones. Zlardwood sawlog grading systems were first developed iri the early 1900's t o assist buyers and sellers when logs were being appraised. Through the years, the supply of high-quality timber has decreased while demand and price have increased. Thus, the significance of evaluat- ing quality during the production, harvesting, and processing of sawlogs has never been more important, Log grades are a tool that can help maximize the potential yield of high-value products from the timber resource.
The hrirdwood log grade specifications presnted here were originally published in 1969 by the USIIA Forest Service's Forest Products Laboratow. This system enables foresters, timber seilers, and timber buyers to wparaw, from woods-run hardwood logs, those logs that are suitable for mmufacture into factory gri-sde lumber, and ta rank the logs into catt?gories of high-, medium-, and low-quality yields. In 1952 the grades were adopted as the official hardwood log grades far use by the Forest Service. Lumber grade yields accompanied the earlier report that was revised in 1966 (Vaughan e t al. 1966). The yields are tabulated by species, log grade, and diamekr class and represent the per- centage of total lumber tally for each class that was assigned to the National Hardwood Lumber Association's (XHLA) lumber grades. Additionral information on lumber g a d e yield has been collected in recent years and is combined with the previously reported yields. Yields for 16 individud species md two groups of fowland oak species anre presenkd. Thew yields, when coupled with lumber prices, provide a means for estimating the vdue of lumber that can be sawed from graded logs.
LOG GRADE SPEC tFiCAT18NS
A Iog grading system can be defined as a set of specifications that is used t o segregate a given lot of cut logs into two or more log grades.' 'I'o that definition has been added the requirement that there be significant dif- ferences in unit value or in end product yield between the log grades.
During the development of the hardwood log grade specifications, many of the variables studied were discarded because they were not reliable in segregating logs into distinct groups. The following are the variables that were included in the specifications.
Log diameter Log: diameter inside bark (dib) at the
small end is the single most important vari- able related to lumber grade yield and log value. The lumber grade yields in this paper are tabuiiatrtd by log gade and scaling di- ameter so that diameter functions as a con- tinuous grading factor within the log grades.
Large Iogs are more valuable than small Iogs because they contain more lumber, and the lumber often is worth more per board foot. Large logs typically contain more defect-free wood than small logs, so more high-grade lumber is produced, This is a result of natural pruning followed by clear wood being laid down over the central core of knots. Large Iogs also result in the production of wider boards; and as board width increaks, lumber grade also increases.
Log length Log length i s a grading factor for grade 1
logs. il minimum length of 10 feet is im- posed, whereas grade 2 and 3 Iogs may be as short 8s 8 feet, Loggers who sell graded logs should buck high-qudity logs into
'Newport, Car1 A., C.R. kockard, and C.E. Vaughn. 1958. h and tree mading as a m e w of measurin ydity. ~ S D A Forest Service mport of the ~st iondi og Grade committee. 31 p,
lengths of 10 feet or more. The 10-foot Clear cuttings minimum lmgth for grade 1 logs relates to length specifications found in the KHLA rules for grading hardwood lumber. The NHLA rules limit the proporliorl of short lumber permitted in a shipment of the better grades.
Log position Whether a log is a butt or an upper log is
a gading factor for grade 1 logs. Both types of logs are permitted in grade 2 . However, butt logs may be as srnali as 13 inches dib, whereas upper logs must scale at least 16 inches dib.
- As part of the grading procedure, the
log's surface is visually divided into four equd faces. Highquality sawlogs are chwackrized by faces with long, defect-free areas called clear cuttings. Sawlogs of low quality have shorter clew cuttings. The rules related to clear cuttings (Fig. 1) were derived from NHLA rules for @ding lumber, and the similarity is obvious when comparisons are inade. The number and length of clear cut- tings and the proportion of a board that is clear are considered when grading a board. The faces of a log are graded much like a board, so these same items are considered for each face.
Figure ?.--Forest Sewice Standard Grades for Hardwood ?actor]( Lumber logsSa
a From Ibast et al. 1979, revised. " Ash srrd basswood butts can bc I2 inches if' they urhcrwrsc rncct rcqutrcmcrlr.i for >mall #l's. ' Ten-inch logs of all species can be #? i f they olhcrwise inet! rcquircmcnr~ for small Il's.
A clear currtng is a portion o f a t'ace, extending ~ h c width cbf rhc faic, !hat it frcc tsf:fcki.t\. ' A i'acc is of the surface of ihc log as divided tengthwi\c.
Otherwise # i Iogs with 41-60% deductions can be R2. Wtherwisc #2 logs with 51 -60% deductians can be X3.
Some of the defects that limit clear cut- tings include limbs, overgown knots, bumps, holes, and bird. pecks. These are discussed in detail in "-4 Guide to Hardwood Log Grading" (Rast e t ai. 1979). Searns that exknd from the surface to a depth less than one-fifth the diameter of the log a t that point are not considered defects.
Sweep and crook The volume lost due to sweep and crook
is estimated when scanling a sawlog. Excess curvature results in a decrease of both lumber volume and lumber grade yield. See Rast e t al. (1979) for a discussion of how to estimate percent deduction due to sweep and crook. &cause sweep and crook affect lumber grade yield as well as lumber voIurne, the estimated percent deduction is a grading factor.
Scalable defect Scalable defect.s include rot sand shake as
well as sweep and crook. The total deduc- tion is limited in low-qudiity logs because minimum requirements must be present for a log to qualify as a factory lumber lag. The arnourlt of scadable defect is limited in high- quality logs because $he overall quality of lumbt:r is rcdt~ced in lugs with large prapar- tions of these defects.
S o u n d end defect
Sound end defects u~cl~rde gum spots, bird pecks, biwk pockets, and stam. For a com- plete d~scussrsn of these dcfects, see Rast et al (1979) and tockard e t al. (1963). The overall frequency of these defects 1s low, but isolated occurrences may be mtense, resulting tn slgnrficwunt damage to the potentially high-grde lumber. It is necessary t o be alert for such defects because thev oversight may be cntlcd.
PROCEDURE
years, the work has been under the direction of the Northeastern Forest aper iment Station. Ilowever, the procedures have re- mained consistent through the years.
Lag selection, diagraming, and scaling
During the first 20 years of the study, the logs were selected at miill yards. Since 1959, it has been possible &a reference the log to the tree. Eaeh log's surface and end chaxac&nstics were dianamed t o provide a photolike description of the type and size of all abnormalities that could be identified.
Each log was scaled using both the Inter- national 114-inch and Scribner Decimal C log rules.
Sawing and lumber grading
'I'he nearly 20,000 logs were sawed at more than 75 sawmills throughout the Eastern ITgiitcd Staks. As each log was sawed, the resulting boards were numbered se that all lumber couid be referenced to the log from which it was sawed.
Each bortrd was graded shortly after saw- ing, and a tally was maintained that included log num'twr, board thickness, surface measure, and @ad@. For logs sawed since 1959, 41 boards were regraded and measured after air drying.
Log grading and log yields
The log diwanls wexu graded by specifi- cations of the Forest Service Standard Grades for Hrudwood Factory Lumber Logs (Fig. 1).
The lumber tally data were processed by Iog so that total lumber tally could be parti- tioned by lumber grade and thickness class. Much of the green yield data collected before 1959 wers converted to dry yields by con- version factors developed by G m m o n (1971).
Lumber grade yields For each species m d log gsade, we de-
Data used m thls study were callecwci over termined the percent%@ Iurnhes grade yields a period of 40 years. Mu& af the origind by diameter class. Lumber s a d e yields for work was carried o u t under the direction of the foIiowiltg 12 species represent dry yields the Forest Products Laboratov. En recent (Tables 1-36). Species included me:
basswood biack oak paper birch chestnut oak yellow birch northern red oak black c h e w scariet oak red maple white oak sugar maple yellow-poplas
Green yields me presented for beech, cotton- wood, elm, sap gum, lowland white oak, and lowland red oak ('Fables 3?-54). Green to air-dry conversion factors were not avail- able for these species.
The yields for all dianetPrs are shown in the bot~otom row of each yield table. These averages should not be used for a specific group of graded logs unless the diameter distribution of the group closely matches that of the logs from the table.
To better use the lumber sawed from chestnut oak logs, the boards we often graded and sold under specifications combin- ing the term "worn holes no defect" ((WHND) with the names of standard grades such as Firsts and Seconds. We followed this pso- cedure. If you wish to estimate the yields of lumber graded by the standard lumber grades, we suggest the following conversion from tabular grades to standard grades:
Tabular Lumber Standard Lumber G r d e Grade
FAS "- tVHND 1 C F I F -- WIiNU 2C SEL WEIND 2C 1C WHND 2C
The lumber thickness distributions by species and log grade are presented dong with the yield tables. Use of the thickness distributions when determining log value is dincuswd below.
Overruns
Overrun is the percentage difference between net log scale and lumber tally. Over- run values for both the International 1/4- inch and Scribner Decimal C log rules accom- pany the lumber grade yields (Tables 1-54),
APPklCATOON OF THE GRADES AND YIELDS
The factors ctjnsidered in log gradkg discussctd earlier include log size, pos ; i t i~@ surface defecb, straightness, and soundness~ When gradhg logs, you shouid develop a system that includes these factors. We suggest the following:
@ Measure =ding diamekr to the n e a r e s t inch.
@ Measure lo$ length to the last wholdfoot. s Determine whether the log is a butt o r EILP~
upper log. @ Eskblish the !seation of dl defect indi-
cators-"swppt?rs"--on the log's s u r f a c e and ends.
e Locate the clear cuttings and the grading face.
e Measure sweep m d crook and e s t i m a k scalable defect.
@ Dewrmine the log's grade.
Because a log's grade is equd to the g r a d e of the third &st face, it i s often dvantagearss to position the faces so that one face is a$ lower grade than the others.
The technique of log $raEfing emnot be perfected wiaou t actual field ins tmct ion and practice. Visits to local sawmills arwd logging jobs will prove invduable in becoming a c q u h t e d with surface and end defects and how they affect kurnber grade. Instruction in tog gading is offered by the USDA Foresd Service, S h t e and Private Fsrest~gr, ,and by many states and forestry sckools. Pf ou are interested in learning how to grade h & w o d logs, we encourage you to contact one of these agencies.
Bucking Proper bucking will provide better lunn-r
grade yields than poor bucking practices- If a sawmill operatur purchases graded fags, log buckers will benefit by understmdibwB and applykg the grading rules. The same true where the laggers are employed by %be
=mu. A compfeb discussion of bucking for grade is included in P e b (197 1).
A! tocation The initial docation of wolds-mn logs
hb the various log clws-veneer, con- sbc t ion , locd use, pulp, md factory lum- h r s lhou ld be We decision of the bucker. & you have learned, factory iumkr logs me d i ~ d e d into log grades 1 ,2 , and 3. Depending on markets and costs, an operator may choose to saw only ce grade 3 lop; or to sort out the veneer c l w logs from the grade 1 and 2 Iogss; or to proess grade 1 and 2 logs at a mill different from that used to process
3 logs.
Timber cruising The hardwood log grades have somethes
k n appGd to logs in standing trees. Prob- lems often are encountered when estimating brpckhg win&, hside-bmk dimekrs , interior eulli, and len* of cbar cuttings. These dif- ficulties are compounded as graders attempt ta gade the upper logs.
An alternative to g a d k g logs in s m d h g tmes is available. In 'TlCIardwood Tree Grades For Factmy Lumkr," Hanks (1976) de- (~Cltibb?d a ~ystem of tree grades r e q u f i g Ithe grader to consider only the butt log. The butt log is grzuied by nearly the sarne spcificaGons described in this pawn', and th is Ipade bcomes the tree's p d e . Included atn? yiekds f'or 11 spcies: yellow birch, paper birch, red maple, sugar maple, yeflow-poplar, bIwk cherlry, b;15swaod, nort;hern red oak, black oak;, ==let oak, white oak, and chest- nut oak. Yields for graded aspen trees are p r e ~ n t e d in ""Lumkr Grade Yields Far Cmdhgl! Aspen Logs and Trees" (Hanks and BP.isbin 1978).
Log valuation We stat& earlier that log grades were
developed to assist buyers md sellers when logs we appraised. In the following examples we demonstrak how the lumber grade yieids, thickness distributions, and overruns can be used to predict the value of lumber that can be sawed &om a log. We used l u m k r price quotations &om the weekly Hatdwood Mar- ket Report publish& by Abe Lemsky.
wia: Yellow Bht& Log w d e : 1 %ding &meter: 13 inches
Lumber price Lumber R&ict& per t h o u m d Lumber @ d e yield' b o d feet vdue
Percent
FAS 16.8 FIF 9.2 SEL 4 .6 1. C 29.7 2 C 15.7 3 A 7.5 3 B 16.5
Total 254.60
a See table 7.
tefls you that 1,000 b o d feet of 4f4-inch lumber from grade I, 13 inch yellow birch logs me worth $274.60. Lf you , want to dewrmhe lumber value for the thickness distribution presented in Gable 7, a weighted price for each lumber grade can be calculated as indicakd below for PAS:
Thickness Percent Lum ber price class per thousaind
(inches) of volume bad feet
PPoUars
FAS weighted priee = $418.94/M bf.
Weighbd prices for all lumber grades could be calculated, and used to d e k m i n e lumber vdue per M bf of grade I, 13-inch yellow birch Iogs.
The next step is %o estimate the lumber volume of the log being considered. A 13- inch, 116-foot log scales 115 board feet by the International 114-inch log rule. You may wish to adjust &at estimate up or down if
you heve wliiable ove ? w e e &at an umf.
scraled IS inches. B cent were subtsacted h m 115 bawd feet, a
mpresenb the esthated value of air-dry lumber that can be sawed from a 13- inch, l&foot, grade 1 yelbw birch log. To p&ict tfie value of the log at the mill or decked in the wods , subbwt the costs of trernspo&ing and eonve*g the log into a&- dry lumber.
Q ~ ~ I B P O D , E. 1- aurd & m e of h&wa& alr-dhylssg. USDA For. Sew. Res.
Wh, L e h d F. 71976. W w d kme USDA Far. Sem. h s .
Hanks, Leland F., and Robert L. Briirbb. 71978. h k ~6 yields for d e c 8 send USDA For. Sen. Re$. Pw. NE429. 13 g.
~ockard, e. R., 2. A. ~ubm, and R. D. nkr. 1%3. Glde defesh trm h a w 4 W b I* U.S. lDe&s. w., A@c. fflmd. 244.39 p.
Petro, F. d. 1971. PC- anal bucking hmdwdr. How to improve your paatit. Can. For. Sew., niep. Fa&. and For., PuM. 1291.140 p.
Rast, Everettc? D., David L. Sjontaenaran, and Glenn
h d w d 1~ gpading. (Hte.vi~d) . Gen. "I"ecfi. Rep. NE-1. 32 p.
Vmghasl, C. L., A. @. Wollln, K. A. McDsndd, and
aod lw ~paded far m d a r d hunber. USDA FOP. Sem. Res. Pap. FPMS. 52 p-
ACKNOWLEDGMENT We thank the many indkiduds aurd groups
who wiSf;f?d with the field portion of this report, especidly Roswell D. Ca~penter, formerly with Northeastern Forest Experi- ment Station, who wid& this work before his retirement.
Key to Symbols for Tables 3 - 5 4
No. logs-actual number of logs sampled
Scale
Int. 114-inch rule-International 114-inch log rule. Scribner Decimal C rule-Scribner Decimal 6: log rule. Overrun (Pct.1-lumber tally minus net scale divided by net scale.
NNLA lumber grade yields (actual)--actual lumber grade yields (green or dry) in percent by National Hardwood Lumber Association lumber grades. FAS - First and Seconds F 1 F - Firsts and Seconds one face Sel -Select Saps - Saps, yellow-poplar only IC - No. 1 Cornman 2C - No. 2 Common 2A - No. 2A Common 2B - No. 2B Common S W -Soundwonny 3C - No. 3 Common 3 A - No. 3A G m m o n 3B - No. 3B G m m o n SSE Sound square edge TBR --Timbers WIdND - Worn Hales Na &feet, chestnut oak only
M f e No. 1 2 3 4 5 6 7 8 3 10 I I
index for Lumber Grade Yield Tables
Wk B w w w d B m o a & I 3seswd Paper binch Paper bireh Paper birsh Veilow b h h Yellow b i r d Yellow b* Bhek cherry Black cheny Bheh cherry Red maple Red mwhr b d mapb Sugaa maple Sagax mraple Sugar rnqle Bhck oak Black oak Black oak mestnut oak Gheshut o& Chestnut oak NorChern red oak N o f i ~ m red oak NorUlern red oa% Scakfet oak Scaall~t aa% Scarlet oaL Wib a 3 Whik m&
Table No.
33 34 95 36 37 38 39 40
species
WhiC oak VeUow-popta YeUoplr-gcrplar Yelliow*plar Beech (green)
diameter gs lumber {inches) Gross Gross Net Over- blly FAS SEL l C 2C 4C Net Over-
run run .- -
- - - B o a r d f e e l - - - - Percent - - - - B o c l r d f e e t - - - - Percent Boardfeet - - - - - - - - . - . - . - P e r c e n t - - . - - . - . - . . - .
Percentage distribution of log grade 2 yields, by thickness
Table 18.-SUGAR MAPLE: lag grade I : d r y lumber grade ylsid, by aceling dlameter
Scale L%ling Total NHLA lumber grade yields (actual)
diameter g; In t , 1%-inch mle Scribner Decimal C rule lumber
(inches) Cross Net Ove' mn Gross Net Over- run tally PAS F1P SEL l C 2C 3A 3B -
- - - - B o u r d [ e e t - . - - Percent - - . . R o a r d f e e t - - - - Percent Boardfeel - - - - - - . . - . - . - . P e r c r n t . - . - - - - - - - - - -
Total tally ( h a r d feet) 5,266 1,135 7,373 2,495 1 2 1,046 2,808 16 101
Table 38.-BEECH: log grade 2 green lumber grade yield, by scaling dlameter -- - --
-- Scde NHLA lumber grade yields (actual)
Int. 114-inch rule Scaling No, Scrjbner Decimal C rule Total diameter lumber (inches) logs Gross Net Over Groirs ~ e t Ove" -tally FA§ SEL l C 2C SW 3A 3B SSE TBR
Table 39.-BEECH: log grade? 3: green lumber grade yleld, by scaling diameter --
Scale -- NHLA lumber grade yields (arlual) Senling, a ,
Int. 1/4-inch rule --- Scribner h c i m a l C rule - Total &ameier NQ. Over- Gross Net Over. lumber (inches) logs '"s' Net run run tally PAS SEL lC 2C SW 3A 3 3 SSI$ TBR
Hanks, Leland F., Glenn L. Gammon, Robert L. Brisbin, and Ever- ette D. Rast.
1980. Hardwood log grades and lumber grade ields for factory Iwaber logs. Northeast. For. Ex Stn ~roomalf Pa. 92 p. ( U ~ D A #orbr. Sen. Res. Pap. NE-468)
The USDA Forest Service Standard Grades for Hardwood Factory Lumber Logs are described, and lumber grade yields for 16 species and 2 species rou s are presented by log ade and log diameter. The grades enatle Lesters, log buyers, andyog sellers to select and y d e those logs mitable for conversion into standard factory grade umber. By using the ap ropriate lumber ade yields, log buyers
and sellers can appraise t f e logs in terms orexpectad lumber r d e volume and value. This report su ersedes an earlier report on ard- wood log grading, Forest Service L a r c h Paper FPL 63.
832.15--525.1-853
Keywords: Log quality; end product yields; log value