(6) There are a number of "impregnation" methods of preserving timber, and their practice is spreading rapidly. Of the various preservative processes, those using coal tar creosote and zinc chloride have proved most efficient. The purpose is to force the preservative into the pores of the wood, either by painting, soaking, or putting under pressure. Such impregnation methods double or treble the life of railway ties. It is now being used with great success to preserve electric wire poles, mine-props, piling, fence-posts, etc.
Wood preservation has three great advantages, it prolongs the life of timbers in use, reduces their cost, and makes possible the use of species that once were considered worthless. For example, the cheap and abundant loblolly pine can be made, by preservative methods, to take the place of high priced long-leaf pine for many purposes.
PRACTICAL SUGGESTIONS FOR STORING LUMBER.
Under the hasty methods prevalent in the mill, very little wood comes to the shop well seasoned, and it should therefore be carefully stored before using, so as to have the fullest possible air circulation around it. Where the boards are large enough, "sticking" is the best method of storage, i. e., narrow strips of wood are placed at short intervals between the pieces which are piled flat. The weight of the boards themselves helps to prevent warping. Boards set upright or on edge are likely to be distorted soon. It is often wise to press together with weights or to clamp together with handscrews boards that show a tendency to warp, putting the two concave sides together. Then the convex side is exposed and the board may straighten thus: Fig. 58.
By wrapping up small boards in paper or cloth in the intervals between work on them, they may be kept straight until they are a.s.sembled.
[Ill.u.s.tration: Fig. 58. Clamping up Boards to Prevent Warping.]
Another precaution to take is to be sure to plane both sides of a board if either is planed, especially if the board has been exposed to air-drying for some time.
WOOD MEASUREMENTS.
Lumber is a general term for all kinds of sawn wood. Logs may be sawn into timber, that is, beams and joists, into planks, which are 2" to 4" thick, or into boards which are from 1/4" to 1-3/4" thick. These may be resawn into special sizes.
Lumber is measured by the superficial foot, which is a board 1" thick, 12" wide, and 12" long, so that a board 1" thick, (or 7/8" dressed) 6"
wide and 12" 0" long, measures 6" B. M. (board measure). Boards 1"
or more thick are sold by the "board foot" which is equivalent to 12"
square and 1" thick. Boards less than 1" thick are sold by the square foot, face measure. Dressed lumber comes in sizes 1/8" less than sawn lumber. Regular sizes are:
5/8" dressed to 1/2"
3/4" dressed to 5/8"
1" dressed to 7/8"
1-1/4" dressed to 1-1/8"
1-1/2" dressed to 1-3/8"
2" dressed to 1-7/8"
Any of these may be dressed down to thinner boards, or resawn on a special band-saw.
In ordering it is common to give the dimensions wanted, in the order of thickness, width, and length, because that is the order in which dimensions are gotten out. E. g.:
6 pcs. quar. oak, 7/8" 6" 3"0"
2 pcs. quar. oak, 3/4" 7-1/2" 15"
If a piece wanted is short the way the grain goes, the order would be the same, thus: 3/4" 11" (wide) 6" (long). That is, "long"
means the way the grain runs. It is always safe to specify in such a case. It is common when small pieces are ordered to add one-quarter to the cost for waste.
In large lots lumber is ordered thus: 800" (B. M.) whitewood, dressed 2 sides to 7/8", 10" and up. This means that the width of any piece must not be less than 10". Prices are usually given per "M," i. e., per 1000 ft.: e. g.: ba.s.swood may be quoted at $40.00 per M.
When thin boards are desired it is often economical to buy inch stuff and have it resawn.
Some lumber is also ordered by the "running" or lineal foot, especially moldings, etc., or by the piece, if there is a standard size as in fence-posts, studs, etc. Laths and shingles are ordered by the bundle to cover a certain area. 1000 4" shingles (=4 bundles) cover 110 sq. ft. with 4" weather exposure. 100 laths (1 bundle) each 1/4" 1-1/2" 4"0" cover about 150 sq. ft.
There are several methods of measuring lumber. The general rule is to multiply the length in feet by the width and thickness in inches and divide by 12, thus: 1" 6" 15" 12 = 7-1/2 feet. The use of the Ess.e.x board-measure and the Lumberman"s board-measure are described in Chapter 4, pp. 109 and 111.
THE SEASONING AND MEASURING OF WOOD.
REFERENCES:[*]
SEASONING.
_For. Bull._, No, 41, pp. 5-12, von Schrenk.
Dunlap, _Wood Craft_, 6: 133, Feb. "07.
_For. Circ._ No. 40, pp. 10-16, Herty.
Barter, pp. 39-53.
Boulger, pp. 66-70, 80-88.
_Wood Craft_, 6: 31, Nov. "06.
_For. Circ._ No. 139.
_Agric. Yr. Bk._, 1905, pp. 455-464.
MEASURING Sickels, pp. 22, 29.
Goss, p. 12.
_Building Trades Pocketbook_, pp. 335, 349, 357.
Tate, p. 21.
[Footnote *: For general bibliography see p. 4.]
CHAPTER IV.
WOOD HAND TOOLS.
The hand tools in common use in woodworking shops may, for convenience, be divided into the following cla.s.ses: 1, Cutting; 2, Boring; 3, Chopping; 4, Sc.r.a.ping; 5, Pounding; 6, Holding; 7, Measuring and Marking; 8, Sharpening; 9, Cleaning.
1. CUTTING TOOLS.
The most primitive as well as the simplest of all tools for the dividing of wood into parts, is the wedge. The wedge does not even cut the wood, but only crushes enough of it with its edge to allow its main body to split the wood apart. As soon as the split has begun, the edge of the wedge serves no further purpose, but the sides bear against the split surfaces of the wood. The split runs ahead of the wedge as it is driven along until the piece is divided.
It was by means of the wedge that primitive people obtained slabs of wood, and the great change from primitive to civilized methods in manipulating wood consists in the subst.i.tution of cutting for splitting, of edge tools for the wedge. The wedge follows the grain of the wood, but the edge tool can follow a line determined by the worker. The edge is a refinement and improvement upon the wedge and enables the worker to be somewhat independent of the natural grain of the wood.
In general, it may be said that the function of all cutting tools is to separate one portion of material from another along a definite path. All such tools act, first, by the keen edge dividing the material into two parts; second, by the wedge or the blade forcing these two portions apart. If a true continuous cut is to be made, both of these actions must occur together. The edge must be sharp enough to enter between the small particles of material, cutting without bruising them, and the blade of the tool must constantly force apart the two portions in order that the cutting action of the edge may continue.
The action of an ax in splitting wood is not a true cut, for only the second process is taking place, Fig. 59. The split which opens in front of the cutting edge antic.i.p.ates its cutting and therefore the surfaces of the opening are rough and torn.
[Ill.u.s.tration: Fig. 59. Wedge Action.]