Instructions on sawing hardwood logs and edging and trimming hardwood lumber for grade and value recovery

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Title:
Instructions on sawing hardwood logs and edging and trimming hardwood lumber for grade and value recovery
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Unknown
Creator:
Telford, C. J
Forest Products Laboratory (U.S.)
Publisher:
USDA, Forest Service, Forest Products Laboratory ( Madison, Wis )
Publication Date:

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Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 29309878
oclc - 230461457
System ID:
AA00020558:00001

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FOREST PRODUCTS LABORATORY t FOREST SERVICE
.4S52.1(Sawing methods)* U. S. DEPARTMENT OF AGRICULTURE
^SMALL SAWMILL IMPROVEMENT /
PRACTICAL POINTERS TO FIELD AGENCIES F .- ...


/ /

INSTRUCTIONS ON SAWING HARDWOOD LOGS AND EDGING
.. .. i ,
AND TRIMMING HARDWOOD LUMBER FOR GR-,E AND VALUE RECOVERY


Principles for grade-sawing logs are almost nonexistent in the
sense of recommending a set procedure to be followed for all logs having
like classes of defects. The recommendations given should lead to
improved quality in a majority of such logs sawn and serve as a start
in grounding sawyers on grade-sawing. With the experience gained in
opening up logs a sawyer should explore how to extend grade recovery
beyond the recommendations given.

To recover the highest possible value from a log, the high-grade
material should be sawed to factory lumber and the lower-grade to factory
lumber or to construction items. A common practice is to try to saw all
material above No. 2 Common grade into factory lumber and to cut construc-
tion items from the other material that can qualify. The market price per
thousand board feet for upper grades of factory lumber usually increases
' with stock thickness. Recommendations cannot be made that all small mills
should cut thick stock, because the limited production at a small mill can
result in excessive handling costs. The cutting policy with respect to
the type of products from the lower-grade portions, and the thick stock from
the-higher-grade portions should be determine-d jpr each individual mill.

The actual sawing practice for grade-sawing factory lumber should be
to work the high-grade material from the better faces by taper-sawing them,
as described later, before taking much from the poorer fa ez,'Pand then to
turn to a different face as the grade drops below that p.r-4. ed by adjoining
faces. This process of working around the log is usuaki rofitable if it
results in raising the grade from No. 53 Common to No. 9. common.


Dividing the Log to Faces, and Sequenc2Qnu- rning
-- *. ........
Jld oo fu how it :*r ul~d
As the log is transfer to the carriage, decide on how itsf
be divided into four cutting faces and the pro-bable sequence to be follOwed
in sawing them. Deciding on one face automatically fixes the other three.
A mirror at the deck entpf the t1gck reflecting a view of the/ end farthest
from the sawyer as the 'I is against the knee is helpful in judging the
influence of end defectsIn determining faces ak .rpbable sawing sequence.
,'_ Univ. of Flor;,

------ i
Report No. R899-27 '


SMaintained at Madison 5, Wisconsin in cooperation with the University of Wisconsin
Agriculture Madison







For clear, sttaiht, soUndl 0ggj with the pith at the .approximate
center it is immaterial how the log id divided into faces) and the cutting
sequence from one face to the next is that involving the least delay. Thus,
at mills turning down, the Cant is turned down 90. At mills turning up,
the cant is turned at least 180 frofm the first face. If the pith is off-
center, the log should be placed so that one face is perpendicular to the
longest radius.

Logs with straight splits, wind shakes, or seams (fig. 1, A)] are
placed so that the crack is at the board edge to be taken out in edging.
Thus the log is placed so that the crack coincides with the radius half-
way between the radius bisecting the first face and that to the bolster
(fig. 1, B). However, if face 2 (fig. 1, B) promises high-quality material
and hence should be taper-sawed, a slab is taken from face 4 before turning
the log to the position indicated in figure 1, B. Sawing face 1, as'indicated,
automatically results in taper-sawing face 5. At right-hand mills turning
down, the sequence is indicated by figure 1, B, At right-hand mills turning
up, the sequencee is usually faces 1, 3, 4, and 2.

Logs with spiral cracks (fig. 1, C) are placed so that one end of the
crack is as for logs with straight cracks and the damaged zone is down and
back toward the knees (fig. 1, D). At mills turning down, the first face
is usually sawed until the crack appears on a board edge, then the other
faces are successively worked; but where spiral cracks extend a third or
more of the circumference, the unaffected faces are sawed deeply before
recovering short pieces from affected faces (fig. 1, D). At mills turning
up, face 1 is worked lightly, face 35 is slabbed, face 2 is worked deeply,
face 1 is worked nearly to the pith, and then face 35 to finish.

Logs with ring shake, dote, or rot (fig. 2, A). When restricted to
the center, these defects do not influence the manner of dividing the log
to faces or sawing sequence. The unmerchantable core is boxed and discarded.
Logs with shake or rot in the outer zone are placed onto the carriage so
that a cutting face is parallel to the straight line connecting the ends
of the arc of shake or the long axis of the rot area and the face affected
is sawed last (fig. 2, B).

Logs with spider heart (fig. 2, C). Spider heart does not influence
the manner of dividing the log to faces or sawing sequence. The spider
heart is boxed and cut to low-grade material or discarded.

Logs with worm holes (grub, shot, or pin) (fig. 2, D) should be
placed on the carriage so that faces visibly free from them are sawed
p-rr to turnii.n to the affected areas.

Ind.:a or, of degradrin" effects listed up to this point usually
are (-' fr te ens ... of "s log Indicators detected from surface
ir pec:u bud clus-ers (fig. 5. A), bird .'ccs

1.. P.f ',re0 ri this re !ors ex-.,pt .TeS C, 4, A, and the drawings are
from U. S. Dept. of Agx. Hai:.book Ho. 4, "Log Defects in Southern Hard-
0,(ods." June i'., )


S' -27





















B 4


J- .

LAI < A


C


Z M 86719 F


Figure l.--A, straight seam; B, schematic drawing of cutting
sequence for a log with a straight crack (right-hand mill);
C, spiral seam; D, schematic drawing of cutting sequence
for a log with a spiral crack (right-hand mill).


A


- ".









2-' 'w- ^
'
f f'lcv.) .mdil


r


B


1~


D


Figure 2.--A, ring shake; B, schematic drawing of cutting
.7luence for a log with ring shake (right-hand mill);
C, spider heart; D, grub channels.


7, M .7?0 F


p
























5


C D


Figure 5.--A, adventitious
C, bump; D, burl.


bud cluster; B, heavy bird peck;


z M 86721 f.

















B


C D


F'qir' 4.--A, canker; B, conk; C, hole; D, unsound knot.


A


7, M 86f. F


















A


B


Figure 5.--A, c-.-erzr.:-.'-ths; B, old wound.


z M 86725 F














OK 4 39 / C \j i /
19
20











2 2


S412
C/ D
12 12
r / / /2\\^A \\

r ~~/ 18 \A I\\



18
-J











Figure 6.--Schematic drawings of cutting sequence: A, on log
havirng three high-grade faces (right-hand mill); B_, on log
having two high-grade faces adjoining (right-hand mill);
C, on log having two high-grade faces opposite (right-hand
mill); D, on log having one high-grade face (right-hand mill).
4 8T F
C D


Figure 6.--Schematic drawings of cutting sequence: A, on log
having, three high-grade faces (right-hand minll); :B; on log
having two 'Agh-grade faces adjoining (right-hand mill);
C, on log having two high-grade faces opposite (right-hand
mill); D, on log having one high-grade face (right-hand mill).
7. M 6,7P4 F






(fig. 3. B), bulges.. bum.irrs (fig. 5, C). burls ,fig. 5, D), butt scars,
cankers (fig. 4, A), conks fig. 4, B), holes (fig. L, C), knots (fig. 4, D),
overgrowths (fig. 5, A), ard wounds (fig. 5, B), can be treated as a group
in their influence on the ;,anner j dividing the log into faces and sawing
sequence. Logs will include the full range between those with few indicators
affecting localized arEa -o many dispersed over the surf:'e. Visualize
the indicaxor-fre- perimeter zone as possible faces for in,' 'ally placing the
log and then successivel;- turn the log so as to cut the high-grade material
from these faces before curting deeply into the defective ones. Thus, for a
log with three high-gra-e faoes, the defective one should be slabbed and
turned down for mils turning iown fi. 6. A) and ilaboed and turned up
180' for mills turning up. wijth the defective face being sawed. last.

Logs with two high-grade faces adjoining are slacbed on each of the
low-grade faces. Or. mills u.rl.in, down, they are then placed with one high-
grade face up and The other to 'he saw. After the first high-grade face is
sawed, the log is turned down Q90 (fig. 6, B). Where turning up is practiced,
the log is p.,aced with one low-grade face to the saw and the other up, is
slabbed an-l turned 130, and the high-grade face is worked to degrade, turned
up 90, slabbed, and turned 180 to the other high-grade face.

Logs with two ,posite high-grade fares are placed with one to the
saw regardless of the turning method. After the high-grade material is
sawed from this face, the log is turned down 90 at mills having turn-down
equipment, slabbed, and turned down 90, and the high-grade material is
sawed from the other good face (fig. 6, C). At mills having turn-up equip-
ment, the log is turned 180 after the first face is sawed and the other
good face is then sawed. In both case> high-grade faces are usually taer-
sawed as described later.

A log having a single high-grade face is placed with this face
against the knees. At mills turning down, a 90 turn is used for successive
faces (fig. 6, D). At mills turning up, the sequence after sawing the
first face is 180, 900, and 1800.

Where a clear face adjoins one having one or more defects that seem
likely to be removed in edging, the log is placed so that these defects will
be near the edge of the defective face; but cankers, conks, and holes are
indicative of extensive defects not likely to be removed edging, and hence
should center the poor face.

Logs with sve-p should be placed on the c' r-iage with the crook
out sfig. 7), and -he four faces should be succ,, siveiy worked in the
sequence dictated by iu"'..g cqui'irnt. Better grade recovery usually
results from g- -tir,g widest board from the laces Tbah a' at T.he top and
bottom in reference to the first face ,aw-d.


Sawing the Log


It is nmpc tant that the location of faces,; be fixed in accordance with
the factors outlined. The high-grac.., faces are usually sawed parallel to the


Report No. R89'-27






bark, but the low-grade ones in the most convenient way to speed up the
work. If a high-grade face is opposite a low-grade one, the good one will
be sawed :'allel to the bark either by placing the poor one against the
knees and setting out the small end of the log or by simply placing the
good face against the knees and stabbing the poor face first.

If high-grade faces are opposite, and for logs characteristically
free of defects nearly to the pith (red oak, ash), the process is to place
cne good face against the knees and to saw the other without regard to
parallelism, but not at first going far into this face. For logs charac-
terized by interior defects that extend beyond the pith zone (sugar maple,
birch), the process is Lo set out the small end enough to permit a slab
of uniform width the full length of the log (fig. 8. A). When the opposite
good face is turned to the saw, ihis process is repeated (fig. 8, B); but
after this face is cut and before another is turned to, the cut is "straight-
ened" by retracting the taper levers, setting the small end back against
the knees, and sawing the face to produce a cant with opposite faces parallel
(fg. 8, C). The intention is to take out the taper from the low-grade
material in the core instead of from high-.-ade material in the outer zone.

In slabbing parallel to the bark, the face of the slab should be
the minimum width required by the prospective board grade -- 6-1/2 inches
for grades above No. 1 Common and 5-1/2 inches for No. 1 Common or lower.
*~:~n sawing any face, usually 4/4 lumber is taken from next to the slab
to minimize edging waste, but when slabbing a face opposite to a previously
sawedc one, the sawyer slabs so that the final piece will conform to size
requirements, thicknesses, or widths of the intended item. Faces indicative
cf high-grade material are sawed deeply; those indicative of low-grade,
lightly. The usual practice is to continue sawing a face until the grade
drops to that promised by the adjoining faces. This progressive turning
continues until either the central portion is sized to meet construction-
item specifications or until the grade improvement fails to pay. For small
mLls specializing in cutting factory lumber, such turning is justified so
long as lumber better than No, 5 Common can be cut.


Edging


Material for factory outlets is normally edged to get the maximum
width possible in inches and fractions; for construction-item outlets, it
is edged to conform to definite width specifications.


Instr tions cr:n edging material f:or fatocry outlets

The minJmiwr width for J factory lumbcr is 6 inches for FAS and
5 inches for Common. Normally, a shririfrae allowance of 1/16 inch per inch
of width is made, so that green Fi. should be at least 6-5/8 inches and
c1 Common at least. 5-5/16 i chess in1 width Boards are usually edged
.'ith the narrower cr barik face up




0
2












4






I I
I I
\ r ) I 1














A 4 BC

Figure 7 (top).--Schematic drawing of cutting sequence on log with sweep (right-
hand mill).
Figure 8 (bottom).--Taper-sawing method by setting out small end of log. A, small
end set out and boards cut parallel to bark; B, log turned 1800, small end set
out and boards cut parallel to bark; C, small end set back against knees and
7 M 67o5 F cant cut to parallel sides.














-- -- - - ^ -f -^ I F
---.-- S8 2 "x 12'= 8 BSF.
Cz9#"x/2'- 9 8.F


-"--- -- --' . .. .FAS-- -"x8'Q 4 F

C / 2 3 48"x 7'= 5 8.F
0 I2 3 4 5 6 78 9 FEE T


FAS
C" AS"


I COMMON


Figure 9.--Schematic drawing of suggested edging and trimming for three variations
encountered. A, indicated edging for common and select grades on a butt cut;
B, for common and select grades on a cut with feather ends; and C, for common
and select grades on a wasp-waist type of cut.


Z M bb (26 F


. ...-- FAS=10"x12'= IO B.F
C=1 /3"x /2'= 13 B.F






Boards below FAS are edged so that the surface area of the wane or
rot left on the board is approximately equal to the area of sawed, sound
face of the edging (fig. 9). For FAS, wane and rot cannot exceed one-twelfth
the surface measure nor aggregate more than one-half the length of the piece.
Shakes and splits in FAS cannot aggregate in inches more than twice the
surface measure of the piece in feet nor diverge more than 1 inch per foot
of length unless they aggregate 1 foot or less in length, Remqvp by ripping
or trimming or both if they violate the above in FAS or extend more than
one-third the length in Common grades.

All pieces exceeding 16 inches in width should be ripped if the
grade of the resulting two boards does not fall below that of the wide piece.

Eip to raise grade when one-half or more of the original surface
measure is raised at least one grade.


Instructions on edging material for construction outlets

Material is edged to conform to definite width specifications for the
item. Items may be made from a limited number of species and sized to a
restricted series of widths, thicknesses, and lengths, as for car stock and
construction boards. The sawyer, edgerman, and trimmer must know the size,
species, and allowable-defect provisions for such items. Tie2 1/16-inch
allowance per inch of width should be made for shrinkage from green to dry
condition. Material in thicknesses exceeding 5 inches is normally edged
on the headsaw, and since a high percentage of all construction items is
produced by the headsaw from squared cants no edge work is required. The
small amount requiring edging is subject to the size and quality specifica-
tions for the particular product. These products are usually diverse, and
general edging instructions applying to them are impossible of formulation.


Trimming


For factory outlets

Trim each piece 2 inches over the nominal foot, and for beards below
FAS trim so that the surface area of the wane or rot left on the board is
approximately equal to the area of the sawed, sound face of the trim (fig. 9,B).
Where the sawed face does not reach the board end (feather ends) (fig. 9,B),
the termination of the sawed face is regarded as the board end. For FAS,
wane or rot in excess of one-fourth the affected area within 1 foot of the
end must be trimmed, and at least ore-half the area of this last foot must
have clear face. rine rule stated for edging splits in FAS also applies to
trimming them; viz., trim so that splits aggregate no more in inches in length
than twice the surface measure in feet, nor diverge more than 1 inch to the
foot in length, except when 1 foot or shorter.


Bqport TC1. -2 -2)'




UNIVERSITY OF FLORIDA

3IIj i 111262 08926 8980I I I
3 1262 08926 8980


For construction outlets


Trim each item to conform with specific length requirements and
with wane, shake, or crack provisions for the item as listed in the
specifications.



Contributed by
C. J. TELFORD
Small-mill Specialist
February 1951


E. .-,rt No. R899-27