.‘a' - o ‘ . o ‘ n U i ‘ a .‘V O . :5. . .9, 0‘2. - ~ Thesis for the Degree of M. ' MICHIGAN TATE UNIVERSITY . MICHAEL J. moon ' 1974 - - ”yrs 'v -\ .v '( I 8-,] if," 2 reps ‘ ' . 0’ - .n-. . . . --o o .‘l' _ u I . v . . , - . .. . I L”! . - . - , , . -- ' o ' _ o I. .- . Afl- _ ‘I I ‘g . . - .. . 0‘ .- -: . — ‘ .,_. . a . 1 .(10- . .~ ‘ . . I 0 ~ - o .0. r‘ l.‘ ,..- . . "of'° - .J- _ I M ' . . . I g - - o..- . - ~‘ '0 " ‘ ' .U c“, - 1‘ 3" 0-.»\ 0 . - o..‘ ’ ' ._ ’P?/.. 0" pg. .o.l-..- ¢ no I o- -_... - , ~—.:. '5‘ a- fin. . . ..l o n - o - ,J ‘of . I ...y ’.-- .-- .‘.' I ’ . -o- - J-Io .- ‘5‘"-1." '¢‘..‘- a.‘ ‘.u~:.P ,1- “‘0 . . ‘_ -o . on . o -.. . . a . ’v o--’ ~"" ' . - r.“'.' --o~'o 0.0V I.- y‘ ’ , . an o 'd.‘.. -- qs- v o A - . ' . .. a - -. . .'. ’ - ..‘ - .‘VO'u'H -.v '.' .- U ’ ' _ . ‘. '_.'r‘" ‘-/'. ‘._.,' . . __~..... .-' ..-'~ V - . . O t ‘ _ . -. .o o . -- . a -.' O. .r. 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" LIMA Y ”‘3 Pvfiaiigjm Vite g Universff {3} A B S T R A C T The supply of large trees from Michigan's original old-growth forests has long been exhausted. Sixty percent of all growing stock of desirable commercial species is in small trees 7 to 15 inches diameter breast height. Hardwoods make up 74 percent of this growing stock volume. The principle species are aspen and hard maple, each of which constitutes 15 percent of the total volume. Michigan's pallet industry relies heavily on this supply of domestic hardwoods. A production survey taken during 1973 concluded that 80 percent of the bolts used by these mills were of low quality and were best suited for use as pallet stock. On the other hand, this same study estimated that 20 percent of the material being used was from bolts of significantly higher quality. The material obtained from these quality bolts could be redirected to the furniture industry in the form of square dimension stock. Furniture squares and other dimension hardwoods are in demand. The short bolt user has the Opportunity to meet this demand and increase his own profits by perhaps as much as 300 percent. This paper identifies those quality bolts, and provides the users with some facts pertaining to their conversion into furniture dimension stock. SAWING FURNITURE QUALITY DIMENSION FROM SHORT LOG BOLTS By Michael J? Kroon A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Forestry 1974 (x?) ACKNOWLEDGMENTS The author wishes to express his appreciation to Professor Alan Sliker and Dr. Henry A. Huber whose guidance and supervision played an important part in the completion of this thesis. He is also indebted to the U.S. Forest Service (USDA) State and Private and Michigan Department of Natural Resources for providing a portion of the funds for this work and to Dr. Daniel E. Dunmire for his helpful insight with the subject matter. For being a patient, understanding, kind and loving helpmate the author is eminently grateful to his wife, Barbara. ii T A B L E O F C 0 N T E N T S Page ACKNOWLEchiENT S O O O I 0 O O O O I O I O O O I O O O O I O O 0 O i i LIST OF TABLES O I 0 O O O O O O I O O O O O O O O O O O O O O O 0 iv LIST OF FIGURES . O O O O O O O O C O O O I O O O I O O O O O O O v LIST OF APPENDICES O O O O O O O O O O O 0 O I O O O O O 0 O O O 0 Vi INTRODUCTION I O O I O O O O O I O C O I O O O O O O O O O O O O O WOOD SUPPLY . . . . . . . . . . . . . . . . . . . . . . . . . BOLTER SAWS . . . . . . . . . . . . . . . . . . . . . . . . . PALLET INDUSTRY . . . . . . . . . . . . . . . . . . . . . . . POTENTIAL USE OF BOLT LUMBER . . . . . . . . . . . . . . . . SURFACE DEFECTS AND TIMBER QUALITY . . . . . . . . . . . . mV-L‘WH H PURPOSE AND OBJECTIVES O O O O O O O O O O O I O O O O O O O O O O 11 PROCEDURE 0 O O O O I O O O I O O O O O O 0 O O O O O 0 O O O O O 12 SPECIES SELECTION . . . . . . . . . . . . . . . . . . . . . . 12 MILL SELECTION O O . O O O O O O O O O O O O O O O O O O O I O 12 MILL LAYOUT . . . . . . . . . . . . . . . . . . . . . . . . . l4 DATA COLLECTION . . . . . . . . . . . . . . . . . . . . . . . 15 RESULTS AND ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . 18 SAWING TIME FOR BOLT BREAKDOWN . . . . . . . . . . . . . . . 18 PERCENT LUMBER RECOVERY . . . . . . . . . . . . . . . . . . . 20 GRADE RECOVERY FROFI BOLTS O O O O O O O O O O O O O O O O O O 23 APPLICATION OF BOLT GRADES . . . . . . . . . . . . . . . . . 26 CONCLUSION AND RECOMMENDATIONS . . . . . . . . . . . . . . . . . . 29 LITERATURE CITED 0 O O O O I O O O O O O O O O C O O I O O C O I O 34 APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 iii Table L I S T O F T A B L E S Page Distribution of 159 Sugar Maple Bolts by Diameter Class, Bolt Length, and Number of Clear Faces . . . . 16 Square Recovery of 2 1/4 Inch Squares From Four Foot Sugar Maple Bolts . . . . . . . . . . . . . . . . 20 Grade Recovery of 2 1/4 Inch x 2 1/4 Inch Squares by Number of Clear Faces . . . . . . . . . . . . . . . 24 iv L I S T 0 F F I G U R E S Figure Page 1 Cost—Product Value Curve of Primary Producer . . . . . 6 2 Time Required to Saw 2 1/4 Inch Thick Cants and 5 1/2 Inch Thick Cants from Four-Foot Bolts . . . . . . 19 3 Percent Recovery Based on Predicted Yield (Int. 1/4 Inch Log Rule) by Bolt Diameter . . . . . . . . . . 21 4 Dimension Grade Recovery of 2 1/4 Inch Squares by Number of Clear Faces of Bolt . . . . . . . . . . . 25 5 Percent Grade Recovery by Bolt Diameter, Four-Foot Bolts, and PA Bolt Grades . . . . . . . . . . . . . . . 28 Appendix A L I S T O F A P P E N D I C E S Floor Plan of Pallet Mill Used in this Study Production Survey Taken at Pallet Mill, Summer 1973, Mr. David Dyer, Owner . . . . . . . . . Table of Species and Grade Composition (Input) cu. Ft. 0 O O O O O O O O O O O I O O O I O 0 Log Diagram Form Used in Sugar Maple Study Mill Tally Summary Sheet . . . . . . . . . . Bolt Conversion Time Study Tables for 5 1/2 Inch and 2 1/4 Inch Cants . . . . . . . . . Recovery Data for 2 1/4 Inch x Random Width and 5 1/2 Inch x Random Width Cants . . . . . Summary of Grade Recovery by Diameter and Number of Clear Faces . . . . . . . . . . . . Grade Recovery by Bolt Grade (PA-Bolts) . . . Pennsylvania Bolt Grades and Prices, June 18, 1971 Page . 37 . 38 O 39 . 40 . 41 . 47 . 50 .GKD u67' I N T R O D U C T I O N WOOD SUPPLY Accelerated inflationary trends in our industrialized economy have made us all aware of the impending problem of material shortages. U.S. News (29) recently wrote, "In one line of business after another, you hear this growing complaint — Shortages of key materials are getting worse, spreading from factories to distributors and on to retail customers." Business Week (4) states that ”Shortages are hitting plastics, synthetic fibers and other textiles, steel, aluminum, copper, lumber, and paper products." One industry in particular which is experiencing challenges in obtaining material is the furniture industry in Michigan. Particularly those manufacturers using exposed and solid core domestic hardwoods in their production lines are finding themselves forced into using available substitutes that are less expensive and at times less attractive. This shortage of hardwoods is especially acute for grade oaks, yellow birch, hard maple, white ash, black cherry, black walnut, sweet—gum, and yellow—poplar (3). The supply of big trees from the original old—growth forests has long been exhausted. Sixty percent of all forest growing stock of desirable commercial species is in small trees 7 to 15 inches in diameter breast height (27). Hardwoods make up 74 percent of Michigan's growing stock volume. The principle species are aspen and hard maple (mostly sugar maple), each of which constitutes 15 percent of the total volume. Hard maple is a valuable species, and present demand for high-quality logs and bolts exceeds the current estimate of allowable cut for this species (6). One way to cope with the increased demand for lumber is to make better use of small logs. Greater use of bolts will play an important role in attaining this goal. A bolt is defined as tree sections eight foot and smaller. By using bolts, loggers can utilize tree sections considered unmerchantable under present harvesting practices (21). Hardwood stands can also be substantially improved by removing trees that can produce bolts of shorter length and lower quality than would otherwise be permissible for sawlog production. Gill and Phelps (8) suggest that the use of bolt wood by manufac- turing industries increased 61 percent from 1960 to 1965. Manufacturers of wood products have realized that the cutting pattern required for their production lines can often be satisfied better economically by the short lumber from bolts than by cross—cutting and ripping longer lumber. Johnson (13) states that converting hardwood lumber to dimensioned pieces wastes 34 to 40 percent of the original volume. This does not include waste in producing lumber from logs. In addition, the user of dimension stock out from standard lengths of hardwood lumber has to pay freight, handling, and overhead costs on that portion of the lumber that is wasted in producing short dimension stock. Also, he must be concerned with the disposal of this waste and its associated environmental consequences (13). If short dimension stock can be furnished to the user directly from short length bolts, he should achieve substantial savings because he will be utilizing practically all of the material shipped into his mill. BOLTER SAWS Short length bolts are most frequently converted into squares or flat stock by the use of bolter saws. The short-log bolters originated in the New England States over 75 years ago and were used to saw square stock for the wood turning and dowel industries (2). They still serve as producers of squares, but their use is growing for production of flat stock for pallet and furniture manufactures. Two types of short—log bolter are manufactured: the table bolter and the carriage bolter, or short-log carriage. The carriage and table are powered through a set of conical iron and fiber independent frictions. These are placed beneath the carriage and engaged by either foot pedals or a lever. A top saw is also used in some locations where bolts of larger diameter are sawn (2). Bell and Calvert (2) state that two distinct possibilities for improving the utilization of both small and defective hardwood trees are provided by the use of short-log bolters as compared to conventional saws. First, since the bolter is a relatively flexible machine, and as the operator has close control of the sawing, greater care could be taken in sawing for grade and in obtaining the greatest yield from the log. Second, the bolter handles short length material, and trees could be bucked into short lengths with the consequent elimination or reduction of defective material and crook. Three points of economic significance which have stimulated interest in bolter operations are first, the low production requirements, second, the low cost of bolter machines, auxiliary equipment, and plant, and third, it's portability. For these three basic reasons together with the States abundance of bolt type materials, bolter operations have received their greatest acceptance in Michigan's pallet industry. PALLET INDUSTRY Pallet manufacture is the fastest growing lumber consuming industry in the United States. Nationally it consumes more than two and one—half billion board feet of lumber annually - over 6 percent of our domestic production (10). The pallet which had its birth in the mid-1930's, achieved major use when the military services began to use it to speed the warehousing, handling, and delivery of supplies during World War II. The fork-lift truck and the wooden pallet combination created the "cubic concept" of modern warehousing, which permits the use of air space as well as floor space in storage areas and transportation vehicles (23)- Today, the wooden pallet is a basic tool of modern materials handling and automation. It's use can be seen in the automotive, masonry, food and many other industries. In conjunction with the flat pallets are the pallet containers. Pallet containers are being used to good advantage to increase the efficiency and lower costs of storage, handling, transportation, and harvesting of various agricultural as well as industrial products (1). In spite of the optimistic picture regarding economic growth of this industry, it does have its drawbacks. The main problem of the wooden pallet industry is that it has the lowest profit margin of all the lumber and wood products industries. It also has the highest financial mortality rate of all of these same industries (1). It is a business that one can enter with a small investment in equipment and physical assets. This often leads to persons of little or no financial responsibility becoming wooden pallet manufactures. Financial success can come quickly for the energetic business entrepreneur’ with the proper technical and managerial mixture but financial mortality in this industry might likewise be termed quick. Much of the economic difficulties experienced by operating pallet mills stems from milling substantial quantities of logs whose total handling costs exceed the value of the products derived from them. Another source of economic difficulty is that the higher grade materials are sold as low quality pallet stock. These two problems cause a narrow profit margin which has lead to financial instability for the industry as a whole. Knowing ones costs from the standing tree, to the final disposal of the product, and increasing the value of the primary product is important in order to establish a desirable profit margin. Specific publications (2), (9),(10), (12), (25), and (26) can aid the short-log producer in reducing his costs and increasing his product value. This idea illustrated simply by use of cost-product value curves as seen in Figure l. Lowering the cost curve through application of modern conversion techniques or raising the product value curve by means of increasing lumber grade yield will widen the profit margin. FIGURE 1. COST-PRODUCT VALUE CURVE OF PRIMARY PRODUCER —— DOLLARS ——" LOG SIZE *— Reasons for the poor profit performance of the pallet industry in Michigan is that the typical pallet plant lacks the capital and managerial ability to expedite cost reduction. Another limitation is that pallet material is used in a low—value product with minor restriction as to quality or species requirements. Thus to raise the product value curve would require finding other markets for the higher quality material. POTENTIAL USE OF BOLT LUMBER One possible market for this quality material is the furniture industry. As previously stated, increased demands for grade oaks, maples, ash and other species of lumber could be obtained from short dimension stock derived from bolts. It would seem most logical that the largest users of bolts would try to satisfy this market if profitable. There are two possible alternatives for marketing lumber cut from bolts. One is to sort out the number one common and better lumber grades produced at the pallet plant and sell it direct to the furniture industry. This often requires modification of existing hardwood lumber standards for which most pallet stock does not qualify. Also, a sizing problem exists in that the furniture industry requires a majority of 4/4 inch stock. Most pallets are made from other thicknesses such as 5/16 inch, 3/4 inch deck boards and 6/4 inch runners. The second alternative solution is to custom cut squares or 4/4 inch lumber from selected bolts for use in higher grade products. The first requirement for success in the recovery of the optimum potential, in terms of product or value yield of a log, is to be able to recognize the potential of the log. Prior to 1930 there was no generally accepted concept of timber quality. From 1930 on, interest in the field mounted, and the researchers began to examine the relationship between log characteristics and products or value yields. It was then possible to write a set of specifications which grouped the logs by similar characteristics or grades. The Hardwood Log Grades for Standard Lumber are the first of these grades recognized and used by the Forest Service (9). Since the late 1950's the Forest Service has established a program for developing grades of this type for all species (28). With the advent of high speed computers, complex relationships in infinite combinations can make the task of grade formulation possible. SURFACE DEFECTS AND TIMBER QUALITY The need for understanding the factors affecting timber quality are essential for grade formulation. Volume per acre is lower and trees are smaller than in the past. Changing utilization patterns require new interpretations of defects for grading. In regard to bolt quality, factors such as height of bolts above ground, rate of growth, age and number of clear faces all directly affect its quality. Stayton and Marden (24) conducted a study on sugar maple defects and found that the percentage of bark distortions and surface rises that had associated interior defects increased as height of indicator above the stump increased. The interior defects associated with surface rises and bark distortions are closer to the tree surface with increased height above stump, and thus more likely to be in the quality sapwood zone (24). Thus, knowing how the percentage of associated interior defects in the quality sapwood zone increases with height would permit better segregation of tree stem sections into product-use classes. The percentages of bark distortions, flutes, and overgrown seams that had interior defects were significantly correlated with tree age. As tree age increased, the percentage of bark distortions and flutes associated with interior defect increased but the percentage of overgrown seams associated with interior defect decreased. The number of epicormic branches and surfaces rises per tree increased as tree age decreased while the number of overgrown seams increased as tree age increased. Growth rate also plays its role in timber quality in that the number of bark distortions and flutes per tree increased as growth rate increased. Surface features such as knots, birdpecks, insect signs, adventitious bud clusters, and limbs also serve as defect indicators. Various publications describe exterior defects and there associated interior defects, (17) and (24). On trees 7 to 15 inches d.b.h. these defects will limit the length of clear cuttings in lumber sawed from most merchantable sawlogs or bolts (3). A literature review Of previous 10 articles written on bolt grading systems showed that the number of clear faces in a bolt provides a highly significant indication of lumber quality attained from bolts (7), (l3), and (21). Johnson (13) stated that "as the number of clear faces increased, the yield of clear and select squares increased and the yield of common and number 2 decreased." He continues, "the largest recovery of clear and select squares can be obtained by utilizing bolts with two, three, and four clear faces." ¢ It is important to note at this time that the presence of most defects in merchantable logs usually is signified by bark distortions and other surface indicators. ”But bark grows, so indicators lose their usefulness progressively; and in time the indicators may become buried under normal bark growth. It is not always possible to predict the loss of an indicator, the entrance or emergence of a grub, the growth of a new branch or the feeding of a sapsucker (3)." The study of surface indicators and their associated relationship to interior defects is of vital importance and its application will simplify the future task of bolt grade formulation. P U R P O S E A N D O B J E C T I V E S The purpose of this study was to gather research in the area of bolt grades, and examine, in a practical manner, it's application to the bolter mill operations in Michigan's pallet industry. Inherent in the purpose, are the following objectives: 1. Identify those quality bolts procured by pallet manufacturers, that could be converted into furniture dimension. Determine the lumber dimension grade yield from those quality bolts using National Hardwood Lumber Association grade rules. Predict the dimension recovery from bolts based on predicted yields using the International 1/4 Inch Log Rule. Establish the time necessary to convert quality bolts into furniture dimension. ll P R O C E D U R E SPECIES SELECTION Hard maple is a "universal” industrial specialty wood. For any purpose where hardness, strength, wearing ability, and good finish are required, it is very desirable (11). The close-grained wood can be bleached and stained to look like cherry. It also is well adapted for bending purposes as in chair legs and backs and also is well suited for turnings. The Hardwood Market Report (16) ranks hard maple second only to birch as one of the most valuable Northern Hardwoods. With these facts along with Michigan's abundance of bolts, hard maple was selected for use in this study. MILL SELECTION The mill selected for this study is located in LeRoy, Michigan, 10 miles south of Cadillac, owned and managed by Mr. David Dyer. The primary product of this mill is a standard industrial flat pallet using both hard and soft woods in its construction. The mill purchases both stumpage and cordwood from privately owned woodlots in the area and relies on independent loggers to fell 12 l3 and haul the raw material to the mill. At the mill, the logs are unloaded with a tractor unit equiped with a front end hydraulic loader, and bunched in an adjacent storage yard. The logs are then bucked into pallet length bolts and transported to the mill for conversion. Several factors were influential in determining the selection of this mill for the study. Among the most important were the simplicity of the mill operation, the availability of required species, and the expressed interest of the owner to participate in the study. The simplicity of the mill was important in order to obtain an accurate tally from each individual bolt. Other plants were excluded because of numerous resaws and rip saws which result in the dispersion of material from one bolt to several different machines, this would greatly increase the difficulty of getting an accurate count from any one bolt. This mill also had the required species in quantity and quality. Various production samples taken during the year showed as much as 34% maple, 12% beech, 8% basswood, and the remaining species consisting of disproportionate units of pine, oak, ash, elm and cherry. Appendix C lists species and grade distribution as obtained from a random survey conducted by the author during the summer. The Forest Products Laboratory suggests other factors that should be considered, as listed below: 1) The log supply should be great enough to allow adequate 14 time for diagramming the logs without slowing down the normal production of the mill. 2) The log deck or holding yard should be large enough to allow adequate diagramming space and time. 3) Logs should not be covered with mud that obscures defects on end or bark surfaces nor should the bark be absent. MILL LAYOUT This pallet mill is a garage-like structure approximately 20 feet x 50 feet with a poured concrete slab as the floor base. All equipment is secured to this base (see Appendix A). The mill contains three major pieces of equipment - a head—saw, trim—saw, and slat saw. The head-saw, located perpendicular to the loading deck, is a 40-inch diameter - 945 r.p.m. Brettrager bolter saw. Its primary function is to break the bolts down into 3 l/2 inch or 5 1/2 inch thick x random width cants. The cants are then sent to a swing cut—off saw where they are trimmed to the length required to fill the order. The cut to length cants are then carried over to a Brettrager slat saw equiped with a 36-inch diameter saw - 1,050 r.p.m. and sliced into deck boards or runner stock whichever may be the case. The cut stock is then carried to the nailing room and nailed into the flat pallets by using pressurized air-nail guns. At full capacity, this mill is capable of producing 3.4 M board feet of pallet cut-stock each eight hour shift. It requires a minimum 15 of 5 people to operate the mill with an additional supervisor to control log supplies and other managerial duties. (See Appendix B for production data.) DATA COLLECTION For this study 3.2 M board feet International 1/4 inch rule, 12 foot hard maple logs were selected. Each log was bucked into 48- inch or 72-inch length bolts then scaled, diagramed and graded. (See Table 1.) Net bolt scale was obtained by subtracting the amount of defective material from the gross scale. Defective material includes bolts with decay and wind shake; bolts with crook and twist were also eliminated. Each bolt was diagramed using standard Forest Service forms. Bolts were theoretically quartered; each quarter representing a face and defects recorded on the diagram forms using appropriate defect symbols (18). End defects were also inspected and recorded when visible. Each bolt was then numbered at the ends so recovery data could be collected from individual bolts. Appendix D shows the diagram form used in this study. The sawing pattern used in this study was that of sawing around. The first slab was removed from the face containing the most defects. After its removal, the bolt was turned down 90° so that the defective side faced the table. The bolt was then alligned parallel to the fence and another slab removed in order to expose a 3 to 4 inch face. Sawing parallel to the bark maximizes the yield of straight—grained stock, 16 TABLE 1. DISTRIBUTION OF 167 SUGAR MAPLE BOLTS BY DIAMETER CLASS, BOLT LENGTH, AND NUMBER OF CLEAR FACES. BOLT LENGTH AND NUMBER OF CLEAR FACES DIAMETER CLASS 4 FEET 6 FEET (INCHES) 0 l 2 3 4 O l 2 3 4 TOTAL 6 O 7 O 8 l l 9 2 1 l 1 1 6 10 2 5 1 l 2 4 4 19 ll 3 4 5 9 3 2 4 1 31 12 1 3 9 13 1 2 3 2 2 36 13 5 3 3 l8 2 2 1 34 14 l l 4 7 1 14 15 1 3 4 l l 10 16 2 4 6 17 l l 2 3 7 18 l 1 19 2 2 TOTAL 2 10 15 33 63 4 7 13 14 6 167 17 which is an important criterion for furniture dimension (l8)- Two and one-quarter inch cants were then removed consecutively until an apparent loss of grade occurred at which time the bolt was turned down and the process completed until total bolt conversion. Each cant removed from the bolt was then carried to the slat saw where it was squared. The squares were then recorded by bolt number and graded following generally the grading standards established by the National Hardwood Dimension Manufactures Association. (See Appendix E.) The squares were then self-stickered and banded for transportation. Self—stickered squares facilitates faster air drying thus thought to reduce possible blue stain degrade. R E S U L T S A N D A N A L Y S I S SAWING TIME FOR BOLT BREAKDOWN During this study, time values were recorded for bolt conversion whenever possible. The unit time measured was the actual minutes required to convert the bolt into 2 1/4 inch x random width cants. Variations in time were observed within each diameter class due to sawing various grade bolts. The sawyer was asked to turn the bolt down when there was an apparent loss in grade. Thus bolts in the lower grade classes required more turning while clear bolts were converted the quickest. Sawing time increased as a linear function of bolt diameter up to 14-inch diameter bolts. Data points were best fitted to the equation § = -l.OO + .2620 (x) where § equals the minutes required to convert the four foot bolt and x equals the bolt diameter. The correlation coefficient was calculated to be .9957. (See Appendix F.) Bolts 15 inches - 20 inches exceeded the bolter saw capacity and required additional sawing time for slab removal. However, other bolter saws such as the J.W. Penny Model B are equipped with an overhead saw which is designed to handle the larger bolts. In another part of this study, time values were taken for converting bolts into 5 1/2 inch thick x random width cants. As was 18 l9 expected, more sawing time was required to produce 2 1/4 inch cants than was required for cutting 5 1/2 inch cants. The regression equation § = —.6243 + .2114 (x) was calculated with a correlation coefficient of .8997. Results from these two studies are shown in Figure 2. FIGURE 2. TIME REQUIRED TO SAW 2 1/4 INCH THICK CANTS AND 5 1/2 INCH THICK CANTS FROM 4 FOOT BOLTS. E: O (D Lu 2 2 [6) o ”/ g / 0 e [.— U) 1 L‘.‘ 3 GD 3 l 0 " z / I! " G) 5477?.RAN00M lDTl-I CANTS g a 244W RANDOM WIDTH CANTS p. O 6789lOl| l2 l3l415l6 BOLT DIAMETER IN INCHES 20 PERCENT LUMBER RECOVERY Recovery data was obtained directly from the mill tally record sheets. The squares from each individual bolt were counted, and actual board footage calculated. Percent recovery equals the actual board footage in the squares divided by the volume of wood in the bolts as measured by the International 1/4 Inch Log Rule. Table 2 contains the percent recovery for four-foot bolts. TABLE 2. SQUARE RECOVERY OF 2 1/4 INCH SQUARES FROM FOUR-FOOT SUGAR MAPLE BOLTS 1 2 3 4 5 Diameter Predicted Actual Z Recovery Ave. Number of Class Volume Mill Tally 2 1/4" Squares Inches (Int. 1/4") Bd. Ft. Bd. Ft. Col. 3 é-Col. 2 per Log 9 10 12 120% 5 10 15 16 94% 7 11 18 17 95% 9 12 23 20 87% 10 13 28 21 75% 11 14 33 25 76% 13 15 38 31 82% 17 16 43 33 76% 17 17 48 34 71% 18 MEAN 86% As the diameter of the bolts increased, the total yield decreased when measured as a percentage of the predicted yield. The recovery data from 2 1/4 inch cants was plotted by bolt diameter and percent recovery for bolts 9-14 inches. The results showed that one could expect a square recovery of 86 percent based on the predicted Int. 1/4 Inch Log Rule. PECOVE RY PERCENT 21 Once the bolt diameter approached 13 inches however, recovery leveled off at approximately 78 percent. (See Figure 3.) FIGURE 3. PERCENT RECOVERY BASED ON PREDICTED YIELD (Int. 1/4 Inch Log Rule) BY BOLT DIAMETER. I50 R I40 \ IZO AJA\ IIO \ loo \ \ U3 0 S7g/ G so s 91 G) 5 7 . . 0 A PALLET DECKEIOARDS 4‘ BOLTS 60 O 2'4"><2'/4” SQUARES 4’ BOLTS so 56789lOl||2|3l4l5|6 BOLT DIAMETER IN INCHES 22 This was the case in similar studies by Redman and Willard (22), Johnson. (13% Bell and Calvert (2). Redman and Willard (22) also investigated the yield of usable furniture dimension cut from logs 26, 35, 43, 51, and 72 inches long. They found that the length of the bolt had no effect upon yield except in the percentage of usable dimension that was full length of the bolt. In another related study conducted as a part of this project, recovery data was collected from bolts which were processed into pallet material. Instead of slicing the bolts into 2 1/4 inch cants, as was done with the hard maple, these were processed into 5 1/2 inch cants. Deckboards 3/4 inch x 5 1/2 inch x 48 inches were then removed from the cants and recorded by individual bolt number. The results were tabulated (Appendix G) for bolts 7-13 inches giving an overall mean of 106% recovery based on International 1/4 Inch Log Rule. As the bolt diameter approaches 11 inches, recovery percent will level off at approximately 85 percent as shown in Figure 3. The difference in overrun is inherent to the log rule and could also be the result of grade sawing. The sawyer turned the bolts around, removing the outer-quality material. The waste was in the outside slabs, the sawdust, a wedge—shaped center, which contained the pith and usually mineral stain. On the other hand, the waste incurred in producing the deckboards was in the sawdust and the outside slabs only. The defective centers went into pallet dimension. 23 GRADE RECOVERY FROM BOLTS Grade recovery data was analyzed by using the bolt diagram forms and mill tally sheets. Preliminary examination of the diagram forms indicated a correlation between usable square material and the number of clear quarter faces on a bolt. Bolts with four clear faces had a higher percentage of clear square material than those with three, two, or one clear faces. Lumber grade recovery was analyzed as a function of clear faces. An increase in the number of clear faces resulted in a higher percentage of clear and select squares. A reduction in the number of clear faces resulted in an increase in Common and No. 2 squares (Appendix H). Bolts with four clear faces had an average of 60 percent clear, 14 percent select, 7 percent Common, and 18 percent No. 2. (See Table 3.) There was no observed percentage increase in the number of clear squares with an increase in diameter for bolts with four clear faces. For bolts with three clear faces, the number of squares reduced to 43 percent clear, 22 percent select, and increased to 10 percent common, and 23 percent No. 2. Bolts having three clear faces with diameters 14 inches to 17 inches had more clear squares than bolts 10 inches to 13 inches. Those bolts having two clear faces showed 25 percent clear, 20 percent select, 13 percent common, and a sharp increase to 39 percent No. 2. Here again, those bolts ranging between 10 inches to 13 inches had a lower percentage of clear squares than those 14 inches and larger. When the number of clear faces was reduced to one and zero, 24 the percentage clear squares was only 5 percent, select 20 percent, common 25 percent and 41 percent No. 2. (See Figure 4 for graphed results.) Overgrown knots, seams, and heavy bark distortions had a serious degrading influence on bolts up to 14 inches. Bolts 14 inches and larger were able to grow enough wood over the defects so it was possible to produce some clear and select squares before the defects became apparent on the exposed surface of the bolt. The large number of common and No. 2 squares is a result of the mineral stain and decay found in hard maple. Unsound knots, overgrown knots, and large bumps seemed to contain a large amount of decay which caused staining in the longitudinal directions. This stain is undesirable for exposed solids and turnings causing a reduction in grade, usually to NO. 2 or common. TABLE 3. GRADE RECOVERY OF 2 1/4 INCH x 2 1/4 INCH SQUARES BY NUMBER OF CLEAR FACES NUMBER OF NUMBER OF PERCENT SQUARE YIELD BY DIMENSION GRADE CLEAR FACES OBSERVATIONS CLEAR SELECT COMMON No. 2 No. 3 4 64 60.27 13.53 6.45 17.81 1.95 3 43 42.83 21.64 10.38 23.18 1.97 2 36 25.16 19.76 12.58 38.76 3.74 1 5 7.14 18.41 20.32 47.38 6.75 0 2 - 22.62 36.91 23.81 16.67 25 FIGURE 4. DIMENSION GRADE RECOVERY OF 2 1/4 INCH SQUARES BY NUMBER OF CLEAR FACES FOR ALL BOLT DIAMETERS CLEAR =90 '7. DEFECT FREE SELECT = 75 07. DEEECT FREE - CE>MM IN = 63 0?. DEFECT FREE / N >.2 = Is”+ 5017. 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