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 FOREST PRODUCTS LABORATORY t FOREST SERVICE 
 U. S. DEPARTMENT OF AGRICULTURE 
 
 . 4S£ 7 i2J. ( Sawing methods ) * 
 • SMALL SAWMILL IMPROVEMENT 
 
 PRACTICAL POINTERS TO FIELD AGENCIES 
 
 INSTRUCTIONS ON SAWING HARDWOOD LOGS AND EDGING 
 AND TRIMMING HARDWOOD LUMBER FOR GRADE 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 determined ft>r 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 faqe^, x and then to 
 turn to a different face as the grade drops below N that premised by adjoining 
 faces. This process of working around the log is usually x^rofi table if it 
 results in raising the grade from No. 3 Common to No. © firammon. 
 
 CA" 
 
 sy 
 
 Dividing the Log to Faces, and Sequence- i' 
 
 '■:■ 
 
 As the log is transf 
 
 trning 
 
 ed to the carria 
 
 iage, decide on how "it should 
 
 be divided into four cutting faces and the probable sequence to be followed 
 in sawing them. Deciding on one face automatically fixes the other three. 
 A mirror at the deck enlof the t^&ck reflecting a view of the end farthest 
 from the sawyer as the lip, is against the knee^ is helpful in judging the 
 influence of end defects' 
 
 In determining faces and* »r»bable sawing sequence. 
 
 7^£JJn/ v . of Florida 
 
 Report No. R899-27 
 
 ■v, v 
 
 t Maintained at Madison 5, Wisconsin in cooperation with the University of Wisconsin 
 
 Agriculture - Madison 
 
For clear, straight, sound _lpgs _wlth the pith at the approximate 
 center it is immaterial how the log il divided into faces, and the cutting 
 sequence from one face to the next id that involving the least delay. Thus, 
 at mills turning down, the eant is turned down 90°. At mills turning up, 
 the cant is turned at least l80° froffl 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 k before turning 
 the log to the position indicated in figure i, B. Sawing face 1, as indicated, 
 automatically results in taper-sawing face 3- At right-hand mills turning 
 down, the sequence is indicated by figure 1, B. At right-hand mills turning 
 up, the sequence is usually faces 1, 3> h, 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 3 is slabbed, face 2 is worked deeply, 
 face 1 is worked nearly to the pith, and then face 3 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 lew-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 
 prior to turning to the affected areas. 
 
 Indicators of degrading defects listed up to this point usually 
 are detected from the ends of the log. Indicators detected from surface 
 inspection, such as adventitious bud clusters (fig. 3. A), bird pecks 
 
 —All figures in this report except figures 1, C, k, A, and the drawings are 
 from U. S. Dept. of Agr. Handbook No. k, "Log Defects in Southern Hard- 
 woods." June 1950. 
 
 Hep.- ... R899-27 -2- 
 
 $ 
 
A 
 
 1 
 
 Z M 86719 F 
 
 Figure 1.--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). 
 

 4 
 
 B 
 
 C 
 
 D 
 
 7. M 86720 F 
 
 Figure 2.--A, ring shake; B, schematic drawing or cutting 
 sequence for a log with ring shake (right-hand mill); 
 C, spider heart; D, grub channels. 
 
 it 
 
 ) 
 
Z M 86731 F 
 
 Figure 3.--A, adventitious bud cluster; B, heavy bird peck; 
 C, bump; D, burl. 
 
Z M 86722 
 
 F Figure 4.- -A, canker; B, conk; C, hole; D, unsound knot. 
 
 
I 
 
 v - 
 
 - a i *4 
 
 1 
 
 Z M 86723 F 
 
 Figure 5 ---A, overgrowths; B, old wound. 
 
^777777 
 
 4 3 
 
 SLAB AND TURN DOWN^ 2 
 
 B 
 
 C 
 
 Z M 8672U F 
 
 Figure 6. --Schematic drawings of cutting sequence: A, on log 
 having 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) 
 
 \ 
 
(fig. 3- B), bulges, tumps (fig. 3, C), burls (fig. 3, D), butt scars, 
 cankers (fig. h, A), conks 'fig. 4, B), holes (fig. 4, C), knots (fig. k, D), 
 overgrowths (fig. 5.. A), and wounds (fig. 5; B), can be treated as a group 
 in their influence on the manner of dividing the log into faces and sawing 
 sequence, logs will include the full range between those with few indicators 
 affecting a localized area to many dispersed over the surf-'-e. Visualize 
 the indicator-free perimeter zone as possible faces for Iir ' tally placing the 
 log and then successively turn the log so as to cut the high-grade material 
 from these faces before cutting deeply into the defective ones. Thus, for a 
 log with three high-grade fa^es, the defective one should be slabbed and 
 turned down for mills turning down (fig. 6. A) and slabbed and turned up 
 l80° for mills turning up. with the defective face being sawed last. 
 
 Logs with two high-grade faces adjoining are slabbed on each of the 
 low-grade faces. Or. mills turning 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 90° (fig. 6, B) . Where turning up is practiced, 
 the log is placed with one low-grade face to the saw and the other up, is 
 slabbed and turned l30°, and the high-grade face is worked to degrade, turned 
 up 90°, slabbed, and turned l80° to the other high-grade face. 
 
 Logs with two opposite high-grade fa^es are placed with one to the 
 saw regardless of the urning method. After the high-grade material is 
 sawed from this face, the log is turned down 90° a b 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 l80° after the first face is sawed and the other 
 good face is then sawed. In both caser> high-grade faces are usually taper- 
 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 l80°, 90°, and 180°. 
 
 Where a clear face adjoins one having one or mere 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 net likely to be removed by edging, and hence 
 should center the poor face . 
 
 Logs with sweep should be placed on the cr.rriage with the crook 
 out ^fig. J). and the four faces should be successively worked in the 
 sequence dictated by turning equipment. Better grade recovery usually 
 results from getting widest boards from the faces that are at the top and 
 bottom in reference to the first face sawed. 
 
 Sawing the Log 
 
 It is important that the location of faces be fixed in accordance with 
 the factors outlined. The high-grade faces are usually sawed parallel to the 
 
 Eeport Lie. R899-27 -3- 
 
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 f\ 
 
 be sawed parallel 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 slabbing 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 
 one 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, this 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 
 (fig. 8, C) . The intention is to take out the taper from the low-grade 
 material in the core instead of from high-grade 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 3-1/2 inches for No. 1 Common or lower. 
 When sawing any face, usually k/h lumber is taken from next to the slab 
 to minimize edging waste, but when slabbing a face opposite to a previously 
 sawed one, the sawyer slabs so that the final piece will conform to size 
 requirements, thicknesses, or widths of the intended item. Faces indicative 
 of 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 
 mills specializing in cutting factory lumber, such turning is justified so 
 long as lumber better than No. 3 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 , 
 
 Instructions on edging material for factory outlets 
 
 The minimum width for dry factory lumber is 6 inches for FAS and 
 3 inches for Common. Normally, a shrinkage alLowance of l/l6 inch per inch 
 of width is made, so that green FAS should be at least 6-3/8 inches and 
 green Common at least 3-3/l6 inches in width Boards are usually edged 
 with the narrower or bark face up. 
 
 > 
 
 Report No. R899-2T -k 
 
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 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. Remqfce by ripping 
 cr 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. The l/l6-inch 
 allowance per inch of width should be made for shrinkage from green to dry 
 condition. Material in thicknesses exceeding 3 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 one-half the area of this last foot must 
 have clear face. The 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. 
 
 Report No. R899-27 -5- 
 
For construction outlets 
 
 UNIVERSITY OF FLORIDA 
 
 I llllll till I II 
 
 3 1262 08926 8980 
 
 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. TELFOED 
 Small-mill Specialist 
 February 1951 
 
 Eeport No. R899-27 -6-