/).' GLIDE TO USE OE WOOD AS AN ALTERNATE MATERIAL IN AGRICULTURAL IMPLEMENTS June 1942 \2Bnno(rtiw.}!i> r ^ UNIV. OF FL LIB — , DOCUMPNTf ricPoT DEPOSITORY UNITED STATES DEPARTMENT OF AGRICULTURE FOREST SERVICE FOREST PRODUCTS LABORATORY Madison, Wisconsin In Cooperation with the University of Wisconsin GUIDE TO USE OF WOOD AS AN ALTERNATE MATERIAL IN AGRICULTURAL IMPLEMENTS A. 0. BENSON, Wood- Technologist C. C. BELL, Forester The past few months have witnessed the develonment of shortages in several important raw materials used in farm equipment prior to the war. Duo to the necessity not only of maintaining hut even considerably increasing the production of farm crops the shortage of such raw materials as iron, copper, rubber, etc., cannot be permitted to stand in the way of an output of essential fprm equipment. The notable developments in farm equipment have come in the present generation largely because of the substitution of mechanical for animal power. Steel has replaced wood in many places where it is the hotter material for the use. At the same time steel in various forms has been used in some items where wood can serve without much change either in service or design. Right now it is important that all items of equipment be thoroughly analyzed with the objective of using wood wherever it is adaptable in an effort to conserve metals that are essential in the war program. It is not necessary to go be- yond the uses where wood can be used to advantage to arrive at totals that represent substantial savings of metal and rubber. On the basis of information, both from manufacturing plants and Laboratory research, subject matter is presentee' in this report that will be helpful to manufacturers and to others looking for opportunities to replace critical materials. Implement Parts of Similar Use Requirements Many implements in the agricultural machinery field have parts or assemblies for which the requirements are similar. It is possible, therefore, to group items on a use requirement basis even though the implements embody- ing these part3 may be quite dissimilar. For instance, Guide Handles may be set up to apply to all walking implements, such as plows, planters, cultiva- tors, hillers, and diggers. The function of the guide handles for these var- ious implements is the same, and a material that is suitable for one is suit- able for another. Naturally plow handles must be capable of withstanding greater loads than garden cultivators. But, essentially, if wood will serve for one it will serve for the other. Table 1 is a listing of parts of similar service requirements where wood has been used with satisfaction in the past or where it is reasonable to conclude that it can be used now as a means of reducing the drain on critical metals. At this time mere preference for a given material cannot be a decid- ing factor; it is a matter of necessity to use the most serviceable and eco- nomical material that is available in quantity. Wood, right now, is a material that meets these conditions in numerous cases. R1298 Table 1. — Grouping of farm implement items on basis of similar use requirements Suggested form of wood stock Typical use groups : Lumber Dimension stock Plyrood or fibre board Beams : plows, cultivators : Conveyor chutes : x elevators, shellers, threshers : Conveyor slats : binders, elevators, pickers, loaders : Floors : x wagons, spreaders : Framework : x peanut pickers, poultry batteries, : feeders, grinders : Handles, guide : plows, cultivators, planters : Hitch parts : wagons and other horse-dra^n implements : Hoppers : x d ills, fertilizers, lime sowers, : anters, feeders : Levsrs : harrows, mowers, rakes, plows : Panels : x hammer mills, incubators, threshers, : shellers : Poles or tongues : wheeled implements, wagons : Reels o : x binders, combines : Running gears : vagons, manure spreaders, rakes, drills Skids : x engines, portable feeders and brooders : Tanks : x watering, storage, spraying, cooling : x Table 1 also indicates what 6eems to be the logical form of wood product to use for the various parts. In solid form wood can be bought as lumber in whatever quality classes or grades the manufacturer may elect to use. As dimension or ready-cut stock it is available from both sawmills and plants specializing in fabricated parts. Also millwork and furniture plants may be looked to as potential suppliers of machined and ready-to-use parts. In sheet form plywoods and dense fibre and mineral boards will give service in many cases comparable to that rendered by sheet metal or solid lumber. Where coverage is the chief purpose to be served plywood of two gen- eral types based on adhesive used in manufacture is in the picture: (1) Ordinary or interior type for equipment kept inside or operated outside only in dry weather, and (2) wea.ther-resistant or exterior type for equipment that may be subject to longer periods of exposure to the weatner or to other damp conditions. The compressed fibre boards also come strongly into the picture for coverage purposes. Especially where there is some fire hazard, as in incubators, the mineral boards, such as asbestos-cement or gypsum compositions, have special virtue. Designr. may need altering to make changes from sheet metal to these materials; curved surfaces may have to give way to flat ones, because neither thick plywoods nor wall boards as normally manufactured will take extreme curvature. Wire used extensively in some poultry equipment may be replaced by wooden dowels or wooden lattice work. Choice of Woods for Farm Implements and Equipment Table 2 deals with the selection of species for the component parts of farm implements and equipment. The list is not complete from the stand- point of kinds of machines, but broad types of implements are represented. Tor items not included some comparable machines appear in the list, and con- clusions can bs drawn with respect to the adaptability of wood for the use and the kind of wood that would be suitable. No attempt has been made to list all the woods that might be used for the various implement parts. In some cases the use requirements are not ex- acting, and the list of satisfactory woods might be extended to include any species commonly available. The recommendations for woods take into consider- ation a number of factors, namely, strength properties, ability to stay in place, decay resistance, resistance to v; ear, availability, price, and others. The choice of a wood is based on a, combination of these factors. Occasionally a certain wood is exceptionally adapted to meet ax outstanding requirement, as, for instance, the ability of hickory to withstand the vibration and shock to which a pitman rod is subjected. Broadly, however, woods fall into prop- erty groups, and within these groups there is often considerable latitude for selection. There are the dense (or heavy) hardwoods, such as oaks, elms, hick- ories, ashes, maples, birches; the nondonse (light-weignt) hardwoods represented by such species as the cottonwoods, basswood, yellowpoplar; the dense soft- woods, of which southern yellow pine, Douglas-fir, and western larch are are examples; the nondense softwoods, such as the soft pines, true firs, spruces, and cedars. Naturally there are no sharp lines separating one ;;roup 31298 -2- from another, but on the average the dense hardwoods are stronger than the nondense , the dense softwoods stronger than the nondense, and the dense soft- woods are stronger than the nondense hardwoods. Thus, there are cases where a use requirement is such that the choice of wood may be from more than one group. Where strength is a requirement, the dense hardwoods or dense soft- woods include the suitable woods; where the use is chiefly a matter of cov- erage the suitable wood will most likely be found among the nondense hard- woods or the nondense softwoods. Strength properties alone do not govern the choice of woods. Woods with excellent mechanical properties may not be available in the sizes re- quired, they may not be obtainable through regular lumber market channels, or they may be had only at prohibitive prices. Insofar as possible these various factors have been given weight in preparing table 2. Alternate Names for Species U. S. ?orest Service nomenclature has been used here in listing woods.. In some cases this differs from the commonly accepted commercial or trade nomenclature. In order that there may be no misunderstanding the chief instances where differences occur are pointed out in the following tabulation: Nomenclature in Lists Common Trade Fame Red pine Norway pine Water tupelo Tupelo Sweet gum Red gum Baldcypress Cypress Sugar maple- ■ •' Hard maple, rock maple When oak is listed it is meant to include the commercial white oaks or com- mercial red oaks. White ash includes the ashes accepted in the white ash group. Hickory includes the true hickories as distinguished from the pecan hickories. Southern yellow pine includes principally longleaf, shortleaf, lob- lolly, slash, and pond pines. The dense wood of any southern pine has prac- tically the same strength and characteristics as the dense wood of any other southern pine, and the lighter pieces are more or less alike. Where high strength values are important, longleaf pine, or dense southern yellow pine have been suggested. The term "dense", when, used in connection with southern yellow pine and Douglas-fir, refers to lumber, traded under a density specification. Spruce includes any of the spruces, regardless of snecies, which may be available in lumber form to the fabricating plant. Rock elm refers to the true rock elm only, and not to the elas of other species sometimes designated in the trade as rock elm. R1298 _3_ Table 2. — Substitution in specific implement parts and by kinds of wood Equipment and parts : Serviceable woods Binders, combines (grain, rice, etc.) Decks Reel Divider board Pitman rod Lever Rein guide Rollers Conveyor slats :0ak, sugar maple, southern yellow pine,' : Douglas-fir : Southern yellow pine, red pine, Douglas- : fir, ponderosa pine, yellowpoplar, : basswood : Southern yellow pine, oak, "diite ash, : sugar maple, yellow birch, cottonwood, ; yellowpoplar, louglas-fir :Hickory, sugar maple, white ash, oak : Hickory, white ash, sugar maple, oak, : yellow birch. : White ash, oak, sugar maple : Sugar maple, yellow birch, southern : yellow pine , oak .Yellow birch, beech, sugar maple, hickory, pecan, oak, white ash Brooders ; (poultry, battery type) ! Framework j Oak, sugar maple, yellow birch, southern yellow pine, Douglas - + "ir, white ash Corn shellers j (hand and power) ! Hopper, bang board : Cob stacker : Base : Frame : Panels : Grain and feeder elevators : Cottonwood, sweetgum, water tupelo, black- gum, southern yellow pine, Douglas-fir Southern yellow pine, Douglas-fir Oak, sugar maple, beech, white ash, southern yellow pine, Douglas-fir Cottonwood, yellowpoplar, basswood Southern yellow pine, Douglas-fir, ponderosa pine, white pine, spruce Cultivators (tractor, sulky) : Lever : Hickory, white ash, sugar maple, oak, yellow birch Diggers (walking units) : Handles, beams, and levers : Oak, white ash, hickory SI 29 8 (a) Table 2 (continued) Equipment and parts : Serviceable woods Drills Hopper Footboard Wheels (see wagons) Levers : Yellowpoplar , redwood, baldcypress, : southern yellow pine, western hemlock, : cottonwood, sweet gum : Southern yellow pine, oak, white ash, sugar maple, Douglas-fir .Hickory, white ash, sugar maple, oak, yellow birch Elevators (portable) : Conveyor chute : Conveyor cleats : Chute derrick : Wagon hoist derrick : Hopper : Southern yellow pine, Douglas-fir, western larch, cottonwood, baldcypress, redwood Oak, southern yellow pine Oak, southern yellow pine, Douglas-fir, western larch Oak, southern yellow pine, Douglas-fir, western larch Southern yellow pine, Douglas-fir, western larch Ensilage and hay cutters 5 Feeder sides : Conveyor slats : Southern yellow pine, Douglas-fir, western larch, yellowpoplar, oak, white ash, cottonwood, basswoocl Oak, sugar maple, beech, yellow birch, white ash, pecan Peed grinders : Hopper : Stand : Skids : Southern yellow pine, Douglas-fir, yellowpoplar, baldcypress, western larch Oak, sugar- maple, white ash, beech, yellow birch Southern yellow pine , Douglas-fir, western larch, any dense hardwood Feeders, hog : Hopper Cover Trough Skids Southern yellow pine, western larch, Douglas-fir, western hemlock:, white pine, red pine Southern yellow pine, Douglas-fir :0ak : Southern yellow pine, Douglas-fir, western larch, any dense hardwood Feeders, poultry Stand and trough H1298 Southern yellow pine, Douglas-fir, redwood, baldcypress, cedar, cottonwood, ponderosa pine, basswood, sweet gum (b) Table 2 (continued) Equipment and parts Serviceable foods Fertilizer distributors Hopper Southern yellow pine, bsldcypress, Douglas-fir, redwood, ccttonwood, basswood, ~hite pine, yellorpoplrr Haraes Sugar maple, yellow birch, beech, white ash Hammer mills Feed tables Side and top-plates Skids Frame Southern yellow pine, Douglas- fir, any dense hardwood Any commercial softwood Southern yellow pir.e, Dougl?s-fir, any dense hardwood Oak, white ash, sugar mapl° , yellow birch, beech Harrows, drag Tooth bars Draw bar Lever Onk, white ash, sugar maple Oak, southern yellow pine, white ash, hickory, Douglas-fir Hickory, white ash, sugar maple, oak, yellow birch Harrows, disc Weight boxes Bushings Levers Oak, sugar maple, white ash Sugar maple, persimmon, dogwood Hickory, white ash, sugar maple, op.':, yellow birch Harrows, spring tooth Draw bar Lever Oak, southern yellow pine, white ash, hickory, Douglas- fir Hickory, white ash, sugpr maple, oak, yellow ^birch Hay loaders Conveyor cleats Rake bars, deck, and deck :0ak, sugar maple, yellow birch, white ash, : hickory sides : Southern yellow pine, Douglas-fir Hay presses Feedtable Division blocks Block setter head Running gear Frame Southern yellow pine, Douglas-fir, red pine Southern' yell o'" pine, yellowpoplar, Douglas-fir, sweetgum, cottonwood, oak Oak, sugar maple, white ash, hickory, any dense hardwood Oak, white ash, hickory Super maple, any dense hardvoou Tcontinued") R1298 (c) Table 2 (continued) Equipment and parts Serviceable woods Hay rakes, sulky- Tooth bars Wheels (see wagons) Oak, sugar maple, white ash, Douglas-fir, yellow birch, southern yellow pine Hay rakes, sweep Teeth : Southern yellow pino, Douglas-fir, oak Hitch parts Neck yoke, singletree, double- tree, evener, and draw bar Oak, hickory, white ash, sugar maple, beech, yello™ birch, rock elm, black locust, s^eetgum, dense southern yellow pine, dense Douglas-fir Hillers, walking Beam, handles, guide Oak, white ash, hickory Hog feeders, rotary Hopper Southern yellow pine, Douglas-fir, bald- cypress, redwood, western larch Incubators •.Western redcedar, redwood, baldcypr^ss Lime spreaders Hopper Wheels (see wagons) Manger partitions Southern yellow pine, Douglas-fir, bald- cypress, cottonwood, yellowpoplar, b as swood , swee tgum :Any commercial softwood, any commercial hardwood Manure spreaders (see wagons) Mowers Divider or swath board Lever Pitman rod Divider board stick Southern yellow pine, Douglas-fir, cottonwood, yellowpoplar Hickory, white ash, sugar maple, oak, yellow birch Hickory, sugar maple, white ash, oak Oak, white ash, su^ar maple, yellow birch, southern yello^ pine, Douglas-fir Pickers and huskers Elevators Conveyor flights Gatherers Southern yellow pine, Douglas-fir, yellowpoplar , cottonwood Oak, birch, maple, beech Oak, sugar maple, yellow birch, southern yellow pine, Douglas-fir, red pine R129S (d) (continued) Table 2 (continued) Equipment and parts : Serviceable woods Pickers, peanut Frame : Southern yellow pine, Douglas-fir, oak, : maple Agitator bars Oak, maple, hickory, white ash, beech, yellow birch, southern yellow pine, Douglas-fir Fan housing Yellowpoplar , cottonwood, bass^ood Hopper Oak, sugar maple, beech, yellow birch, white ash Chute Yellowpoplar, cottonwood, bass^o'od, magnolia Trucks (see wagons) Planters, corn, potato, etc, Hoppers Levers Wheels (see wagons) Southern yellow pine, Douglas-fir, cottonwood , yellowpoplar Hickory, "white ash, sugar maple, oak, yellow birch Planters, garden Wheels (see wagons) Frame, guide handles Hopper Oak, white ash Cottonwood, yellowpoplar , basswood, white pine, red pine, ponderosa pine, gum Plows, cultivators, walking Beams, stretchers, and guide handles Frame Wheel (see wagon) Oak, white ash, hickory, sugar maple Any dense hardwood Plows, sulky and tractor Levers Hickory, white ash, sugar maple, oak, yellow birch Poles, implement :Longleaf pine, Douglas-fir : (dense) Potato sorter and grader Hopper Rollers Platform, draw bar Southern yellow pine, Douglas-fir, oak Oak, white ash, hickory, southern yellow pine, Douglas- fir R1298 (e) (continued) Table 2 (continued) Equipment and parts Serviceable woods Skids, engine and other 'Oak, southern yellow pine, Douglas- fir , western larch, any dense hardwood Sleighs : Runners : Rock elm, oak, hickory, white ash Sowers, hand Hopper Cottonwood, yellowpoplar, basswood, pines, Douglas-fir, spruce Spraying machines (See tanks) (See poles, implement) Stanchions Sido bars Sugar maple, yellow birch, beech, white ash, oak, hickory, pecan Tanks, watering Storage, cooling Baldcypress, Douglas-fir, redwood, cedar, white oak, southern yellow pine Thills : White ash, oak, hickory, southern yellow pine Tongues or poles (See wagons, tongues) Wagons, spreaders Floor boards Sills Scoop boards End ladders Side and end boards Footboards Seat Cleats (see hounds, below) R129S Edge-grained Douglas-fir , edge-grained southern yellow pine, edge-grained wes- tern larch, yellow birch, sweet birch, white ash, beech, oak, sugar maple Southern yellow pine, Douglas-fir, oak, hickory, pecan, ash Edge-grained southern yellow pine , edge- grained Douglas-f ir, edge-grained wes- tern larch, any dense hardwood Southern yellow pine, Douglas-fir, oak, white ash, hickory, yellow birch, beech, sugar maple Yellowpoplar, cottonwood, basswood, oak, white ash, southern yellow pine, Douglas- fir, baldcypress, yellow birch, sugar maple Same as' for floor boards Yellowpoplar, white pine, cottonwood, basswood (f) (continued) Table 2 (continued) Equipment and parts Serviceable woods Wagons, spreaders, trailers, Eubs Felloes and rims Spokes Tongue and reach Axles Bolsters Bolster stakes Sand bolster Hounds, and slider bar Brake bar Brake block Brake bar hanger trucks Bock elm, oak, black locust, sugar maple, sweet birch, yellow birch Hickory, oak, white ash, rock elm, yellow birch, sugar maple Hickory, oak, rock elm, white ash, yel- low birch, sweet birch, sugar maple Oak, white ash, southern yellow pine, Douglas-fir Hickory, white ash, sugar maple, oak, pecan, yellow birch Hickory, oak, white ash, sugar maple, pecan, yellow birch Same as for hounds Hickory, oak, pecan, sugar maple, white ash, yellow birch Hickory, oak, white ash, rock elm, yellow birch, sugar maple, beech Same as for axles Same as for axles Hickory, white ash, sugar maple, oak, pecan, yellow birch Waterers, poultry Stands Troughs Southern yellow pine, Douglas-fir, red pine, baldcypress, redwood Redwood, baldcypress, cedar Wheelbarrows Handles Trays, garden type Trays, utility type Oak, hickory, sugar maple, yellow birch, white ash, elm Basswood, yellowpoplar , cottonwood, sweetgum, water tupelo Elm, oak, sugar maple, beech Windmills Platform Sails Arms Tower Pump pole Ladder Sucker rods Pump jack H1293 Baldcypress, redwood, white oak, Douglas- fir, southern yellow pine, western larch, cedar Baldcypress, yellowpoplar, spruce, basswood Oak, southern yellow pine, Douglas fir Southern yellow pine, Douglas-fir, wes- tern larch, oak, sugar maple, yellow birch, white ash White ash, hickory, oak, southern yellow pine, Douglas-fir Southern yellow pine, oak, sugar maple, yellow birch, Douglas-fir, white ash White ash, hickory, southern yellow pine, Douglas- fir Southern yellow pine, Douglas fir (g) (concluded) Availability of Species During the war period it is impossible to state with certainty the extent to which the individual species are available for farm implement and equipment manufacture. As demand for wood increases with 'expanding military uses and substitution becomes necessary because of limitation of use of critical materials the supply situation is constantly changing. A wood that is available in abundance today may be less available tomorrow. The recent order freezing certain grades of softwood construction lumber is a case in point. However, the shop and factory grades are not frozen so that the sup- ply although narrowed in range may still be sufficient in quantity and quality to meet any demands that might come from farm implement manufacturers and other users of lumber in remanufactured form. Certain hardwoods have been relatively scarce for some time because of abnormal demand for special war uses. White oo.k, white ash, and yellow birch are examples. There are other roods that will give comparable service. Some woods are abundant in certain localities, and yet not generally available throughout the territory in which the farm implement industry is largely concentrated. For instance, black locust is abundant in the Appalachian region from Pennsylvania south into Georgia and Alabama and in parts of the Ohio Valley, yet it comes into the general lumber markets only in small quantities because it is not a general purpose wood. Certain woods with excellent properties are available in the sizes required only at prohibitive prices. Among such' ere dogwood, persimmon, and osageorange. Unless a manufacturer is unusually well located with respect to supply of these woods they should be considered in the unavailable class. Op tional Forms of Wood Stock and Sources of Supply A wood user has much the same option in buying stock as has the metal user. He may buy material in unworked form or he may buy parts for his prod- uct in machined form ready to assemble at his factory. There are many sub- stantial sawmills and woodworking plants that are equipped with dry kilns and machinery that are capable of doing just as good a job as the factories them- selves. For farm equipment plants without woodworking machinery or men fa- miliar with woodworking the purchase of ready-cut parts offers a solution to the problem of changing from metal to wood. For factories equipped with fa- cilities for working wood the opportunity to buy parts cut and dried to their requirements has some distinct advantages. It enables them to increase production at a rapid rate without overloading their wood preparatory shops. Another decided advantage is elimination of a. large lumber inventory with the many items of direct and indirect costs that go with it. The advantage of a substantial back-log of lumber is that the factory is more or less in- dependent of extreme fluctuations in prices and there is also less danger of a breakdown in supply flowing tc the assembly shop. At the present time ceiling inrices on most lumber items have eliminated the danger of run-a^y price3, so that the argument for a large lumber inventory loses much of its force. R1292 _l+- On the "basis of a thousand board feet, cuttings bought ready-cut and cuttings obtained by a factory from lumber in its own shop should not vary greatly in cost. The advantage is usually on the side of ready-cut stock as a factory operator who has included all of his costs knows. It is the advantages aside from apparent costs that often strengthen the case for ready-cut stock. A convenient method of locating sources of supply for lumber and ready-cut stock is through lumber trade associations. Among the lumber associations important from the standpoint of farm equipment manufacturers are the National Hardwood Lumber Association 59 East Van Buren St., Chicago, Illinois Northern Hemlock & Hardwood Manufacturers 1 Association Oshkosh, Wisconsin Southern Hardwood Producers, 805 Sterick Building, Memphis, Tenn. Northeastern Lumber Manufacturers' Association 271 Madison Avenue, New York, N. Y. Southern Pine Association Interstate Bank Building, New Orleans, La. West Coast Lumbermen' s Association 36U Stuart Building, Seattle, Wash. Western Pine Association 510 Yeon Building, Portland, Oregon Appalachian Hardwood Manufacturers, Inc. Ul4 Walnut Street, Cincinnati, Ohio Hardwood Dimension Manufacturers' Association 229 Heyburn Building, Louisville, Ky. A request to the National Lumber Manufacturers' Association, 1337 Connecticut Avenue, N. W. , Washington, D. C, will always bring pertinent information whether the inquiry concerns hardwoods or softwoods. Plywood Were circumstances normal resin-bonded plywoods would be available for many uses. They are especially useful where coverage is the chief requirement. Such plywoods Pre so extremely resistant to moisture that they will withstand prolonged exposure to weather. However, present mili- tary demands for this type of plywood plus the demand for the materials from which the synthetic resin glue.s are made create a situation which leaves limited quantities for ordinary civil uses. R1298 -5- Where equipment is used indoors or is exposed to the weather for only short periods plywoods formed with other glues will give good service. For some uses plywood has qualities superior to those of solid wood. It swells and shrinks less than solid wood when exposed to changes in humidity. It is effectively resistant to checking. It can' he obtained in wide, long panels, and where rigidity is a factor large, unbroken sections have a de- cided advantage over sections of the same size composed of a number of narrow pieces not edge-glued. Plywoods are available in various thicknesses and of different woods. Among the sources for information on plywood supplies and uses are the Hardwood Plywood Institute, 20^ West Wacker Drive, Chicago, Illinois, and the Douglas Fir Plywood Association, 1203 East D Street, Tacoma, Washington. Most local lumber distributing agencies can be relied on for information on plywood that will be helpful to prospective users. Fibre Boards and Wall Boards Of fibre boards there are several that might be considered as al- ternates to plywood. Some of these are hard and stiff, and serve well for coverage. Properly coated they will stand severe exposure to the weather. They may be obtained in large panels, U feet by S feet, and in thicknesses from 1/8 inch up. Another type of wall board is that made from minerals or minerals combined with wood or other fibres. Examples of these are gypsum boards and asbestos-cement boards. These are highly fire-resistant, and are especially adaptable to uses where the fire hazard is a factor to be reckoned with. Information on fibre boards or wall boards is generally available from local building material supply agencies. Classification of Woods According to Important Properties Table U shows in approximate terms the property relationships of a number of the commercially important woods. Provided a prospective user knows the requirements for a specific purpose the table may be used as a guide in the choice of woods for items not included in table 2. Usually the choice is determined by a combination of two or more properties along with the factor of price and availability. Where requirements are not exacting price may be more important than properties of the woods, and again where two or more woods have almost identical property ratings, advantage as represented by price nay outweigh other considerations. For the more complete information on wood properties that every de- signing engineer should have there is available from the Superintendent of Documents, Washington, D. C, the "Wood Handbook," price 35 cents (cash or money order, stamps not accepted). It deals in detail with wood as a mate- rial of construction, and contains data for its use in design and specifi- cations. R1293 -6- Use of Wood in New Forms and by New Methods Hew forms of wood products, new processes, new treatments, new equipment, and new fastenings have come into existence since wood "began to recede from use in agricultural implements. With the exception, however, of the structural use of plywood and dense fiber boards and improved kiln-dry- ing facilities the prospective user or designing engineer should not put too much reliance on using wood in some radically new form. This is not to min- imize the importance of the new developments, but to focus on the obvious fact that the important substitutions of wood for other materials in the implement field for the immediate present will fee through the use of conven- tional materials and forms. The fact that often critical materials are in- volved in the newer developments or that supply facilities cannot be set up at this time is the main reason why the designer must adhere largely to standard form. There are opportunities for the designer to show ingenuity and to devise short cuts using standard readily available forms of material without relying on forms more difficult to obtain. In addition to^the exceptions referred to above there are, however, certain rapidly growing practices that may be expected to find application in this field more readily than others. Reference is made to: (1) Special metal connectors to supplement bolted joints in heavy structural members. Such connectors are available on a license basis from one supply organiza- tion. (2) The lamination of curved or straight members, with moisture- resisting, cold-setting adhesives, by nail, clamp, or machine pressure. G-lued, laminated products are available from a few producing plants which specialize in this business, or they can be made fairly readily by the user. Two uses in which laminated construction is known to hrve been used in the agricultural equipment field are for tongues and quite recently for heavy hoops for storage bins and silos. Mysterious formulae for impregnations or coatings to eliminate the swelling and shrinking of wood have been commonly promoted, but wood still swells and shrinks. Soundly compounded, heavy-bodied coatings are effec- tive in reducing the rate of dimensional change but not the amount of change. Considerable progress has been made in the development of coatings that re- duce end splitting of lumber and logs incident to storage or seasoning. Fairly good f ire-retardant paints are available for special usages if re- quired. Information in this field can be supplied upon request. Wood plastics, plasticized wood, compressed ^ r ood, and similar new products have special utilities and promise, but for quantity nondefense usage at present are practically out of consideration because of the dif- ficulty of obtaining accessory materials or equipment needed in their pro- duction. As a substitute for brass in small bearings or similar parts cer- tain products in the laminated plastic field do come in for consideration if the need is sufficiently important. -7- R1298 Table k. — Broad classification of woods according to characteristics and properties (A, among the woods relatively high in the particular respect listed; 3, among the woods intermediate in the particular respect listed; C, among the woods relatively low in the particular respect listed) Kind of wood Working and behavior char- acteristics : : »h w : CO o u P»c0 O CD Strength properties cu) --»0, •C! ^ CD CO CO . .tJ • to • in 1 ,3 • <0 •V s +» . • rf t& w • • -H a o . r -H CD P,* . 'H ^ (-> -p d • CO CO CO co ji o £1- 2:3 7: 8 : 9 :10 : 11 : 12: 13 : lH Ash, white. A9h, black. Baldcypress Basswood, . . Beech Birch, yellow Cedar, northern white Cedar, western red. Chestnut Cottonwood. . . Douglas-fir.. Elm, soft.... Elm, rock.... Fir, balsam. . Fir, white. . . Hackberry. . . . Hemlock, eastern Hemlock, western Hickory, true. Hickory, pecan Larch, western Locust, black Maple, hard. . Maple, soft.. Oak, red Oak, wnite... Pine, ponderosa Pine, southern yellow White pine group: Northern white... Western white. . . . Sugar pine : A: A : B : 3 : C : . . : A : C : C : A : A : A : : A: B : C : 3 : C : . . ; . . . : C : C : 3 • 3 : C i : B: B : 3 : B : 3 : A : B : A : 3 : 3 : E • 3 ; : C: C : C : 3 : A ; . , : C : C : C . n . p : C : : A: A : C : C : C 1 • . : A : C : B : A : A : 3 : : A: A : C ■ 3 : C ! • . : A : C : A : A : 3 : : C: C : A : A : A : A : C : A : A : C : C : C : : C: C : A : A : A : A : C : A : A : C : C : 3 : : B: B : B : A B ! • • : B : A : A : C : C : C : : C: B : C : C : B > • • : C . C : C : : 3 : C : : B: B 3 ! B : C c : 3 : 3 : A : A : A : A : : A: A: C ! C • C \ • • A 3 : B : 3 3 ; 3 • : A: A- c B C • • ■ • « B : B : A • A jS * : C: C: B 3 ! B B . • • C 3 C C ! C : : C: C B B ! B : B C ! C ■ C B 3 3 : : A: A< C ! B ! C : . . . . . • ♦ • • • C , 3 C C : : B: B: B : B : B : B: B : c 3 : 3 : 3 3 : : B: B: 3 : B i 3 : 3: B : c C : 3 : A: 3 : : A: A: C : 3 : C : • * i A : c B A : A A : : A: A: C ; 3 : C : • • ! • • . < c A : A. A : : A: A: B : B : C : C: A : B ; A A - A: A : : A: A: B : 3 : C : . . ■ A : A A A : A: A : : A: A: C : 3 : C : . . A : C C : A : A: A '. : A: A: B : 3 : C : . . A ; C : C : C : C: C : : A: A: C : B : C : • . : A : C : 3 : .ri. ; A: E : : A: A: C : 3 : C : • . ; A : A : 3 : A : A! 3 . : C: B: B : A : A : B: B : (2) 1 C : C : C: C : : A: A: B : 3 : c : C: A : B : C : A : A: A : : C: C: A : A : A : A: B : (2) ; 3 : C : C: C : : C: 3: 3 : A : A : A: B : (2) : B : B: ■B . : C: C: A : A : A : A: . . . : (2) : 3 : C : C: C : A A C A A C C B E A A C C A E 3 A A 3 A A C A R129S (continued) Table k (continued) Kind of wood Ui fO CD d U d Working and behavior char- acteristics 6/j. •H " ' en O • CD • ' >» CD : rt o cj; o d oj : iu 5w: r-i O d x* o o •H O +3 iz fn +3 O (-, O 0) ^^ Strength properties CO : d t rEl in +J ' y> : ,d WW CD -^ +3 d « d ; a0 c/> ; •H 0) f n d o T3) £-. •H u , -p d '. m C/J en 9 o C-i 2: 3: ^ : 5 : 6 : 7: 10 ill 12 : l 7 , : Ik Redwood : B: B: A : A : B Spruce, eastern C: 3: B : A : B Spruce , Sitka 0: B: 3 A : B Spruce , Engelmann C: C: 3 A : B Sweet gum B: B: C C : B Sycamore A: A: C C : C Yellowpoplar ■ 0: B: 3 i! A : A Water tupelo : A: A: B : C : C A : B • A : B : 3 . C : 3 ! . . . C : B c C : , B B : . A C : , 3 : C : . A : C : A C C c B B 3 3 C 3 : 3 : A : : B : B : : A B : : C C : : B B : : 3 3 : : 3 C : : B ! 3 : 3 3 B C 3 B C 75 ^Exclusive of the all-hear twood grades that are available on special order in birch, cedar, baldcypress, Douglas-fir, sweet gum, southern yellow pine, and redwood. ^Conflicting opinion and absence of adequate test data preclude a definite rating. Placing reliance on high decay resistance is not recommended when this wood is used untreated. R1298 (concluded) Lumber Grading Softwoods Softwood lumber is graded under rules issued by the various regional lumber inspection bureaus or associations. The following table indicates where to go for information on grading the various species referred to in table 2. Lumber Inspection Agencies Kinds of wood Agency or association sponsoring grading rules Address of association Southern yellow pine Southern Pine Inspection Bure au Canal Building, New Orleans, La. Baldcypress Southern Cypress Manufacturers' Assn. -.~f2? Barns tt National : Bank Building, : Jacksonville , Fla. Douglas-fir, western hem- '.Pacific Lumber Inspection lock, western redcedar,: Bureau Sitka 9pruce : : 36U Stuart Building, : Seattle, Washington Eastern white pine, red {Northern Pine pine, eastern spruce : Manufacturers' Assn. :UU38 Wentworth Avenue, : Minneapolis, Mian. Eastern spruce, northern : Northeastern Lumber white pine, red pine : Manufacturers' A.ssn. : 2 7 1 Madison Ave nue , :New York, IT. Y. Redwood : California Redwood Assn. , U05 Montgomery Street, San Francisco, Calif. Ponderosa pine, western :Western Pine Association white pine, western : larch, sugar pine, : western redcedar : 510 Ye on Building, Portland, Oregon Eastern hemlock : Northern Hemlock and : Hardwood Manufacturers' : Association P. 0. Box IOUO, Oshkosh, Wis. Hardwoods Standard grading rules for grading all commercially important hard- woods are issued by the National Hardwood Lumber Association, 59 East Van Bur en Street, Chicago, Illinois. Among the ^oods included are oak, maple, PJ.298 -3- ash, elm, basswood, beech, birch, hickory, sweetgum, yellowpoplar , cotton- '••ood, pecan, locust, tupelo. Also included in the rules issued by this association is cypress. Lumber Prices Information on current lumber prices is published in various trade journals. Among such are the following: American Lumberman, Commercial Bulletin, Hew York Lumber Trade Journal, Southern Lumberman, and West Coast Lumberman. Published price information is chiefly valuable for comparison of species. Prices are quoted with reference to specific markets so that they are not reliable indexes of what the costs might be delivered to cer- tain points distant from the price basing centers. There are no published prices for dimension or ready-cut stock. Seasoning Wood used in the manufacture of farm machinery and equipment will not give its best service unless it has been properly dried before it is installed. Tests made by the Forest Products Laboratory show that wood for outdoor use should be dried to moisture contents of 7 to L4 percent based on oven-dry weight. For use in the dry southwestern states the average should bo 9 percent and the variation in moisture content not greater than 7 to 12 percent. In: the remainder of the United States the moisture content should be about 12 percent and variation not more than between 9 a™* 1*+ per- cent. Wood dried to these moisture contents will give satisfactory service in most items of farm machinery and equipment. It is especially recommended, however, that wood wheel and wagon box parts be thoroughly dried so there will be no further shrinkage after assembly. Moisture Content Tests The moisture content of wood can be determined bv any one of sev- eral methods, the most common of which are oven-drying tests and instan- taneous electrical moisture meters. The oven-drying method is the more accurate but is slow, while the electrical method gives quick results, but is not accurate under all conditions. In the oven-drying method, samples 3.A to 1 inch long in the direc- tion of the grain are sawed from representative boards or pieces. These samples should be cut at least 1 foot froj. the end of the piece to avoid the effects of drying from the ends, and should be free from knots and other defects. Cutting samples for oven-drying tests . — Each sample is weighed immediately after cutting, placed in an oven heated to 212° to 221° 7. , and dried for 8 to 2U hours or until no more weight .is lost. Scales or R1298 -9- "balances with a capacity of about 200 grams and sensitive to 0.1 gram should be used. The following example illustrates how moisture content is computed: (Original weight) (Oven-dry weight) l^ljSramj minus 103 grams = 20 = 0#lg or ig percent 105 grams 10? (Oven-dry weight) Several types of portable electrical moisture meters are available with which the moisture content of wood can be determined directly. In us- ing these instruments sharp, short, metallic terminals are imbedded in the wood, and the electrical resistance read from the instrument in terms of moisture content. The range of most of these instruments is about 7 to 214- percent. Electrical moisture meters measure the moisture content of the wettest wood with which the terminals come into contact. They sre usually- designed for use on lumber or wood parts which are about 1 inch thick and may not be accurate for thicker material — which is normally wetter in the interior than on the surface. In wood thicker than 1 inch the moisture gra- dient may be estimated by using electrodes driven to different depths. These instruments rill also be inaccurate in testing pieces which have for any reason been recently wet on the surface. Air Seasoning Thoroughly air-dried wood will reach a moisture .content of 12 to 15 percent, and is, therefore, usually at or above the 'maximum which should be used for farm equipment parts. For this reason it is important that manu- facturers who have no kiln-drying facilities air dry their lumber to the lowest practicable moisture condition. The methods of piling lumber for air seasoning have been studied in considerable detail, and considerable information is available covering the methods and practices which should be followed in order to get the best results. Following is a summary of these practices as concern the most important damages to lumber during air seasoning. Lumber Pil ing Practices Which Will Reduce Seasoning Dam age To reduce the occurrence of: Checking Wanoing Blue stain and decay Lower the founda- tions. Decrease the spacing be- tween boards and between piles. Use thinner, nar- rower stickers. Place the end stickers so that they project be- yond the ends of the pile. Use end coatings, Use stickers, of uni- form thickness properly aligned and sup- ported, and suf- ficient in number Raise the foundations. Increase the spacing be- tween boards and between piles. Provide one central flared chimney, or a series of narrow chimneys. . Use thicker , narrower stickers. Build narrower piles. Provide short chimneys (l/3 or 1/2 height of pile). Use thicker stickers in the lower part of the pile. Stain or decay occurring through- out the pile. Stain or decay oc- curring in the low- er part of the pile only. R1298 -10- Kiln Drying Advances in dry kiln construction, installation, and operation have been rapid, especially during the past 1^ or 20 years. Most of the old- model kilns do not have the volume or quality of production which is possible in the newer units, in which temperature and relative humidity can bo con- trolled more closely and in which the rate of circulation has been increased greatly. As in the case of air seasoning, detailed studies and research have been conducted covering many important phases of dry kiln construction, operation, and maintenance. The folloring is a summary of these practices as they apply to some of the most important items of damage to wood during kiln drying: Practices Which Will Reduce Eiln Drying Damage To reduce the occurrence of: Surface checking : End checking : Warping Honeycomb Increase the rate of circulation. Use higher humid- ities at the be- ginning of run. Pile more carefully. Use end coat- ings. :Pile more care- : fully, using : more stickers. : Increase rate of : circulation : through pile. : Relieve casehard- : ening. :Use heavy weights : on top of pile. Prevent surface check- ing and minimize case- hardening by using milder drying con- ditions. Get uniform circula- tion throughout pile. Snd Coatings Since rood dries faster from the end grain than from the side grain some kinds of rood, especially in thick sizes, may check and split during air seasoning. For this reason it is often advisable to use s moisture- resistant end coating for air seasoning or kiln drying. Coatings ordinarily used are of two classes. Those ir. the first class are liquid at ordinary air temperatures and can be applied cold. Those in the second class are solid at ordinary -temperatures, and must be heated before being applied. The hot or cold coatings are effective for drying temperatures up to lU0° P. , but for temperatures between lUO° and 170 o hot coatings should be used. The two best cold coatings developed are hardened gloss oil thick- ened with barytes and magnesium silicate (very cheap) and high-grade ?par varnish and barytes (expensive). The gloss oil is made up as follows: The oil should be of a thick grade made up (by the paint manufacturer) of about 8 parts by weight of quick lime, 100 parts rosin, and 57. S parts mineral spirit. To 100 parts R129* -11- of the gloss oil add 25 parts barytes and 25 parts of magnesium silicate. One or two parts of lampblack can be added if a black coating is desired. This coating can be made by any paint manufacturer, or it can be mixed hy the user as needed, in case the proper grade of gloss oil is obtained. Some glosr. oils have little moisture resistance, and it is necessary, therefore, that the coating be made up according to the above formula. Paraffin is a satisfactory end coating for use on material which is to be air seasoned, but its melting point is too low for use on stock to be kiln dried. The most effective method of applying hot coatings is to dip the ends of the stock about 1/2 inch into the coatings. For this reason it is difficult to apply these coatings to large-size material. Hot coatings are effective in the following order: 213° coal-tar pitch (chenp) 25^° coal-tar pitch (cheap) Rosin and lampblack (100 parts of rosin to 7 parts of lampblack) (moderate cost) Preservative Treatment The use of wood in farm machinery and equipment involves only rel- atively few parts and items in which preservative treatment or the use of naturally durable woods is necessary. These parts are, for' example: Skids — for engines, shellers, self-feeders, hog traps, and other wood-mounted items Tanks and silos — for water and fodder storage Foundations and. frames — the lower parts of which' normal 1?" are 'in contact with the ground The need for decay resistance in a wood part will be determined by use conditions. Resistance to rot is necessary in parts which are to be in direct contact with the ground and in parts which otherwise are used under conditions which result in the accumulation of moisture. For use under these conditions it is recommended that the wood parts concerned be treated by one of the following methods: 1» Pressure treatments -— using preservatives such as coal-tar creo- sote or pentachlorrhenol solutions (for part3 which are not to be painted) , or zinc chloride (for parts which are to be painted). Pressure treatment is the most effective, and most expensive, treating method, and need be used only under conditions of high decay hazard. 2. Hot and cold bath treatments - are less expensive than the pres- sure treatments, and can be accomplished at the manufacturing plant. These are the most effective of the nonpressure treatments, and are suitable for de- cay protection under all but the most severe service conditions. R129S -12- 3. Steeping treatments - are generally less effective than the hot and cold bath methods. Mercuric chloride has been commonly used, but zinc chloride, sodium fluoride, and other water-soluble preservatives can be employed. Soaking dry wood in untreated solutions of pentachlorphenol gives some protection with practically any wood and may give excellent results with woods that are easy to treat. k. Dipping treatments - using hot preservatives, such as the cre- osotes or pentachlorphenol solutions, have only limited effectiveness under severe service conditions. 5« Crushing and spraying treatments - that are sometimes used with preservative oils, are the least effective methods of protecting wood from decay. Detailed information on these treatments and the chemicals used is available from the Forest Products Laboratory. Bent Food Equipment Farts Curved members of wood are produced oy band saving or by bending. 3and-sawed parts are more subject to splitting and breaking because the direction of the grain of the wood does not follow the curvature of the piece. Thin stock bends more readily than thick stock; therefore, bent single pieces are sometimes glued together to produce a part of the re- quired thickness. In making single-piece bent members the stock must be softened, and heated usually with steam or hot water, to permit the required defor- mation. Straight-grained material free from defects is essential for bends that involve extreme deformations. Hardwoods, especially elms, ashes, hickories, withstand extreme bending better than softwoods — pines, firs, hemlocks, etc. The oaks, beech, birches, maples, and gums can be successfully bent. Wood that has been steam-bent should preferably be dried on forms or otherwise held to desired shape until at about the moisture content it will have in service is reached. An extremely important factor in bendinr wood successfull ,r is the design of the mechanical apparatus used for ppplying pressure, itony commer- cial losses in bending can be prevented through the use of proper equipment. The use of adequate straps on the tension side of the b^nd and proper ores- sure take-up devises for the ends of the pieces ore features commonly over- looked. This is a clear-cut mechanical problem, not one that has to b e left to chance and the so-celled vagaries of wood. Wood loses some of its strength in bending, the rmount of loss de- pending upon the severity of the bend. Trade directories include the names of concerns that specialize in wood bending. In some cases it may be advan- tageous to investigate the capacities of such plants for undertaking special bending jobs. R129S -13- Wo o d- damaging Insects Implement stock in dry storage is sometimes badly damaged by the larvae of the powder-post beetle, so it is well to be on the lookout for this destructive insect. Evidence of its work is the accumulation of a fine powder coming from holes l/lb to 1/12 inch in diameter. When these holes are numerous they weaken the wood to a considerable degree. Woods preferred by these insects are ash, hickory, and oak; other hardwoods, including maple, elm, and poplar, are affected to a lesser ex- tent. Only seasoned sapwood of these woods is damaged; therefore, wood that has been in dry storage for a considerable period of time needs close watching and preferably old stock should be used before newly-piled material. Since the eggs of the insect are laid in the open pores of the wood any finish, such as paint, varnish, or boiled linseed oil, will effectively prevent infection. If infestation is already present, sterilization may be accomplished by steaming at not less than 130° 3?., treatment in a dry kiln at 180° for 1-1/2 hours is effective for inch lumber, and a proportionately longer time for thicker lumber. Where practical the infestation may be halted by a thorough appli- cation of kerosene or a mixture of three parts kerosene and one part coal- tar creosote. The following points are set down to sum up this discussion: 1. Commonly affected woods are ash, oak, hickory. 2. Keartwood is not affected. 3» Only seasoned sapwood is affected. h. Keep old stock moving. 5* If practical, paint or finish parts to be stored. 6. If practical, sterilize wood with steam or dry kiln treatment. 7« Where practical, halt infestation with kerosene or kerosene- coal-tar creosote mixture. R129S _lh. UNIVERSITY OF FLORIDA 3 1262 08927 3220