Elements of woodwork

Preface To The Series

This series consists of five volumes, four of wliich are intended as textbooks for pupils in manual-training, industrial, trade, technical, or normal schools. The fifth book of the series, the " Handbook in Woodwork and Carpentry," is for the use of teachers and of normal students who expect to teach the subjects treated in the other four volumes.

Of the pupils' volumes, the first two, '' Elements of Woodwork " and "Elements of Construction," are adapted to the needs of students in manual-training schools, or in any institution in which elementary woodwork is taught, whether as x^urely educational handwork, or as preparatory to a high, or trade, school course in carpentry or vocational training.

The volumes " Constructive Carpentry " and " Inside Einishing" are planned with special reference to the students of technical, industrial, or trade schools, who have passed through the \\ork of the first two volumes, or their equivalent. The subjects treated are those which will be of greatest value to both the prospective and the finished workman.

For the many teachers who are obliged to follow a required course, but who are allowed to introduce supplementary' or optional models under certain conditions, and for others who have more liberty and are able to make such changes as they see fit, this series will be found perfectly adaptable, regardless of the grades taught. To accomplish this, the material has been arranged by tojucs, which may be used by the teacher irrespective of the sequence, as each topic has to the greatest extent possible been treated independently.

iii iv PREFACE TO THE SERIES

The author is indebted to Dr. George A. Hiibbell, Ph.D., now President of the Lincohi Memorial University, for encouragement and advice in preparing for and planning the series, and to George R. Swain, Principal of the Eastern High School of Bay- City, Michigan, for valuable aid in revising the manuscript.

Acknowledgment is due various educational and trade periodicals, and the publications of the United States Departments of Education and of Forestry, for the helpful suggestions that the author has gleaned from their pages.

CHARLES A. KING.

Bay City, Michigan.

Preface To Elements Of Woodwork

In preparing this book, it has been the author's purpose to present, in as complete and concise form as possible, the knowledge which every wood-worker sliould possess regarding the care and use of his tools and the material upon which he employs them.

Whether an amateur, apprentice, or skilled workman, whether a carpenter, boat builder, pattern maker, or wood carver, the elementary knowledge of the construction of tools, of sharpening them, and of their adjustment and manipulation is practically the same. The structure of wood, and the necessity of a])plying its peculiarities of grain and texture to the advantage of the work in hand, also is the same upon all branches of woodwork.

While innumerable tools and cutting devices have been invented to enable the wood-worker to accomplish special results economically both as to time and material, a study of them will prove that they all operate upon a few simple principles, a knowledge of which is not difficult to acquire, though skill and judgment in the application of the tools can be attained only by continuous and properly directed practice.

It would be both impossible and unnecessary in a book of this sort to describe these various devices, though in a schoolroom it is a great advantage to have as many of them as practicable, not for tlieir use only, but that the students may become familiar with their purposes and the applications of the fundamental principles upon which each is based.

The actual use of tools may be considered the ABC of woodwork, as it bears the same relation to the finished product of the workman as the alphabet bears to literature, the space between vi PREFACE TO ELEMENTS OF WOODWORK

the mere mechanical facility in the use of eitiier tools or alphabet, being the result of the judgment, skill, and individuality of either the workman or the author.

Thus, if a student acquires the facility to use the tools described in this volume, he will have little difficulty in using other and more complex tools; and when he has mastered the principles of construction involved in the exercises explained in the following book of this series, the "Elements of Construction," and the correct use of the tools involved in making these, together with their applications and combinations, he has acquired the fundamental knowledge of all construction in wood.

CHARLES A. KING.

Bay City, Michigan.

Table Of Contents

Chai'tkr I. Growth of Wood. — Kinds of trees used for lumber; The formation of wood ; Tissues ; Tlie medullary rays ; The grain in trees ; Defects found in lumber ; When to cut lumber . . 1

Chattkr II. Llmherixo and Varieties of Wood. — The manufacture of lumber ; To saw lumber of irregular dimensions ; The grading of lumber ; The testing of lumber ; Surveying or estimating lumber ; Qualities of wood 12

Chapter III, Care of Lumber. — The piling of lumber; Permanent lumber ways ; To minimize the warping of lumber ; Weather-dried lumber ; Kiln-dried lumber ; Moist air kilns ; Induced draft kilns ; Kesults of the two systems ; Filling a kiln ; Length of time lumber should be left in the kiln ; The care of kiln-dried lumber ; Steaming wood ; Preserving wood 45

CHAPTER I Growth of Wood

1. Kinds of trees used for lumber. — (A.) The classification of trees here considered is based upon the method by which the trunk, or stem, of a tree is formed. The term exogenous is appHed to outside growers, around which a layer of wood grows each year, and from which is cut the lumber of commerce. As the wood-worker is interested mainly in trees which grow by this method, we will do no more than mention the endogenous, or inside-growing, trees or plants of the nature of palm trees, cornstalks, etc., in which the woody fiber is formed upon the inside of the stem.

(B.) The new wood formed each year upon exogenous trees is known as the annual layer, or ring; the separate layers being more prominent in open-grained woods, such as oak, ash, and chestnut, than in close-grained woods, such as maple, cherry, poplar, and birch. It is the difference in the character and structure of these layers which makes some woods hard and others soft, some with open and others with close grain, and which also, with the coloring matter peculiar to each kind of wood, causes its individuality and adaptability to certain uses.

(The color and odor of wood are caused by chemical combinations, and are not part of the substance of the wood.) Each of these annual layers is composed of two parts, the formation being shown m Fig. 1, in which the grain of yellow pine is depicted. The soft, cellular, or open, grain,

a, is formed as the sap moves upward in the spring, and the hard, compact grain, h, is formed later in the year. In soft woods the open grain predominates, while in hard woods the compact grain is more in evidence.

The age of a tree may be determined by counting these annual rings upon the stump, though a drouth during the growing season may have at some time so affected its growth as to make some layers indistinct, rendering it impossible to be absolutely sure of the count. In a young tree the annual layers are thicker than when the tree becomes more mature.

(C.) The different kinds of timber which the carpenter uses are cut from deciduous, or broad-leaf, trees, and from coniferous, or needle-leaf, trees. This classification of trees is based upon the difference in the forms of their leaves, the former kind furnishing the ash, oak, walnut, beech, birch, and other woods that are hard to work, as well as poplar or white wood, linn or bass wood, and others which

Fig. i.

Section of Pine.

Yellow soft, cellular grain; h, hard, compact grain.

GROWTH OF WOOD 3

are called hard woods, not in the sense that they are hard to work, but because then- method of growth is the same.

The coniferous or evergreen trees furnish the cedars, pines, hemlocks, spruces, firs, redwood, tamarack, cy- })ress, and a few other woods of the same nature. These woods have a resin which is always present, no matter how old or dry the wood may be, which explains their superior weather-resisting qualities.

2. The formation of wood. — (A.) In the spring the sap begins to flow upward, mainly through the open cells of the cambium (the new growth in the stem, by which the diameter of the tree is increased), and to some extent through the sapwood. As it conies in contact with the air by means of the leaves and the green shoots of the tree, (B.) it gives off water and oxygen, and absorbs carbonic acid gas from the air, (C.) which is formed into starch, sugar, oil, etc.; this in turn becomes part of the sapwood, and forms the compact part of the annual ring, completing the layer for that year.

(D.) The wood is formed by a deposit of matter from the sap, which gradually thickens the cell walls until the cells are filled, when that layer becomes a part of the heartwood, or that part of the tree which is inclosed within the annual laj^ers of sapwood.

(E.) Both the fibers and the cells of the sapwood are filled with water or sap, which may be removed by seasoning, but the sapwood of most trees used for building purposes is not as good lumber as the heartwood, as it is always susceptible to moisture. The exceptions to this will be mentioned elsewhere.

(F.) In all unseasoned lumber from 20 to 60 per cent of its weight is moisture, which must be evaporated before the lumber has its highest commercial value. This may be done by weather drying or by artificial means, the lumber being treated in a specially constructed kiln.

3. Tissues. — (A.) A tree trunk is composed of four different tissues, viz.:

1. The pith (Fig. 2, a), a cellular tissue: this is worthless and its presence in lumber is considered a defect.

2. The wood, which includes the heartwood (6), the sap wood (c), and the medullary rays {g). From this part of the tree the commercially valuable lumber is taken.

3. The cambium (d), which is a thin layer between the sapwood (c) and the bast (e).

4. The bark, which includes both the bast (e) and the outer bark (/). The bark of most trees is worthles^^, but that of chestnut, oak, hemlock, and other trees which are rich in tannic acid is used in large quantities by tanneries.

(B.) The heartwood (b), or duramen, of most trees is the part generally used by carpenters upon the best work. It is firm, compact, and of the color and qualities characteristic of the wood.

(C.) The sapwood (c), or alburnum, is generally light-colored, and in most building woods its presence is considered a defect, though not in. hickory, ash, maple, or yellow pine, and a few other woods ; in fact, in these woods it is often preferred to the heartwood for many kinds of work on account of its color. The alburnum is filled with the active elements of the sap, which are deposited as the sap passes through the trees, and in time becomes part of the duramen, or heartwood. The time required

GROWTH OF WOOD

Fig. 2. — Section of Oak Tree Trunk.

a, pith; b, heartwood, or duramen; c, sapwood, or alburnum; d, cambium; e, bast, or inner bark; /, outer bark, or corky layer; g, medullary rays, or silver grain; po, plain oak; qo, quartered oak.

for sapwood to attain maturity ranges from thirty to one hundred years, according to its kind and age.

(D.) Outside of the sapwood (Fig. 2, c) is the cambium (d), which furnishes the substance upon which the hfe of the tree depends. Here, nourished by the richest sap, new cells are formed, which become either sapwood or a part of the bast. (E.) At (e) is shown the bast or inner bark, which is composed of a woody fiber combined with a tissue of cells. This is elastic, which allows it to expand as the wood grows beneath it. Outside of the bast is the bark (/), or outer covering, which is of a corky nature, and protects the delicate vital parts of the tree.

4. The medullary rays. — Every tree has medullary rays (Fig. 2, g), usually spoken of by wood-workers as the ^' silver streak," or '^ silver grain." These rays connect the center of the tree with the outside, and are more prominent in such woods as oak, beech, and sycamore than in other woods It is to take advantage of the beauty which these medullary rays impart that so much quarter-sawed lumber is used, though lumber sawed in this way is preferred for other reasons, which will be discussed later.

In many woods these rays are so small as to be invisible to the naked eye, as in pine, for instance, which has fifteen thousand to the square inch. Aside from adding much to the beauty of the lumber, they also give strength ; if lumber is dried out too rapidly by artificial heat, it is apt to check, or crack, upon the line of the medullary rays.

5. The grain in trees. — In open or exposed situations trees usually grow more or less gnarled or crooked, which

GROWTH OF WOOD 7

tends to improve the grain. The strength of lumber cut from trees grown as described is impaired, however, l''iG. 3. — Defects in Lumber.

a, wind shakes or cup shakes: 6, heart shakes; c, star shakes; d, branch broken off, showing the method by which the annual layers gradually cover broken branches; e, hard knoi,.

as the wood is more cross-grained than that from trees which grow in the heart of a forest, with practically the same conditions on all sides. As forest trees are continually reaching up for the sunlight, they grow taller and straighter, which makes it possible for straighter-grained lumber to be cut from them, and as the branches are at the top, where they receive the sunlight and air, there are few cross-grained places.

When the annual rings are large, the grain is said to be coarse, and if the rings are fine, the term fine-grained is used to describe it. When the direction of the fibers is nearly parallel with the sides and the edges of the board, it is said to be straight-grained; when the lumber is taken from a crooked tree, it is said to be cross-grained, as the grain follows the shape of the log, while the board is sawed straight. Cross-grained lumber is the handsomer ; in this the fibers, being at different angles with the surface of the board, form a variety of figures, which add much to the beauty of the wood.

6. Defects found in lumber. — (A.) Some of the most common defects found in lumber are wind shakes, or cup shakes (Fig. 3, a), which are cracks following the line of the porous part of the annual rings. These are caused by the action of severe winds. (B.) Heart shakes (Fig. 3, h) are cracks radiating from the center of the tree, and may be found in any kind of wood, as they are the result of deficient nutrition, or loss of vitality. (C.) Star shakes (Fig. 3, c) are caused by the shrinkage of the tree upon the outside, which is the result of a long dry spell of intense cold, or of the deficient action of the sap. Star shakes differ from heart shakes in being larger upon the outside of the tree; the heart shakes are larger at the center.

Shakes of all kinds are common defects and sometimes are so numerous as to make the log worthless.

GROWTH OF WOOD 9

(D.) Discolor ations are caused by decay which has at some time gained a foothold, but which the tree was sufficient!}^ vigorous to overcome ; or they may be due to imperfect or insufficient nutrition, which generally results in the entire tree being affected instead of small places upon the tree.

(E.) Timber grown in a damp, marshy locality is generally of a poorer quality than that grown upon higher ground, as more water is taken up by the roots than can be well assimilated, which prevents the formation of healthy compact wood. Some w^oods are adapted to such soil, the poplar or whitewood, willow, basswood, buckeye, and cypress being denizens of moist or swampy places.

Trees growing where they are exposed f to winds from one direction are apt to assume a spiral growth, which renders the timber almost worthless, as it is weak, and twists badly in drying.

(F.) Trees which have lumps appearing like growths upon them are usually unhealthy. These lumps, or tumors, may be caused by defective nutrition, checks, or shakes, or by the depredations of animals or insects.

(G.) Clefts, or splits, in a tree may be caused by extreme cold, heat, or drouth. They may extend into the tree several inches, and while the blemish will always remain, showing a discoloration or other defect, nature often repairs it so that the strength of the timber is but slightly affected. If these clefts are not healed, rain may find lodgment there, and the sap be so affected that the adjacent wood will be destroyed, and this in time will destroy the tree.

(H.) Eggs of certain insects are also deposited in these clefts, the larvae of which bore into the wood and destroy it. (I.) If it were not for the birds and other natural enemies of these insects, they would increase so rapidly that the lumber supply would be seriously affected, and, as it is, there are very few trees which are not injured to some extent by wood borers. The United States Bureau of Entomology estimates that the damage to trees by these pests amounts to at least $100,000,000 annually.

(K.) Sometimes (as at d, Fig. 3) branches die or are broken off ; this gives the elements access to the heart of the tree and usually causes a permanent injury, as the birds and other denizens of the forest frequently dig out the rotten wood as soon as the weather has had time to do its work, thus giving further opportunity for decay to continue its destructive action. If this does not happen, the wood will grow over the break after several years and leave a loose knot in the heart of the tree, which will be a decided blemish when the log is made into lumber. The sketch shows the endeavor of nature to repair the defect, as the annual rings will eventually close over the break.

The hard knot at e, Fig. 3, is not a serious defect, unless the wood is to be used for finish or where great strength is required.

7. When to cut lumber. — Trees which are intended for the use of wood-workers should not be felled while the sap is in motion. If cut at any other time than midsummer or in winter, the active sap is apt to sour and to cause decay. Owing to the scarcity of lumber, or from avarice, this precaution often is ignored, and trees are felled at any time of year, regardless of their age ; in such

GROWTn OF WOOD 11

cases, much of the lumber lacks the essential quaHties of its kind.

When a tree shows signs of dying at the top, it should be cut down, as the quality of the lumber it contains will deteriorate rapidly.

1. What is meant by exogenous trees? In what kinds of wood are the annual layers most prominent ? Describe the formation of annual layers. What causes the difference in the degrees of hardness of wood? In the color and odor of wood? How may the age of a tree be determined ? Are the broadest annual layers found in young or in old trees ? From what class of trees does soft wood come ? Hard wood ?

2. Describe the motion of sap. What forms the sapwood? With what are the cells of the sapwood filled ? Compare sapwood and heart - wood.

3. Describe the four different tissues in a tree. Describe the inner bark.

4. What are the medullar}^ ra^'s? In what woods are they most prominent? How do they affect the strength of timber?

5. What is the nature of trees which grow in exposed situations? Where are the straightcst trees found? Why does the location of a tree affect the grain ? What is meant by coarse, fine, straight, and cross-grained lumber ?

6. Wliat causes wind shakes ? Heart shakes ? Star shakes ? How may they be distinguished from each other? What causes discolorations ? What is the usual character of timber grown upon marsln^ ground ? W^hat woods are adapted to low ground ? What sometimes causes spiral growth? What do lumps and excrescences upon a tree generally signify ? What causes clefts in trees ? What are the results of clefts ? Does nature perfectly repair the cleft ? What is the usual result of a branch being broken off?

7. What is the per cent of moisture in green wood? Should very young trees be cut ? Why ? How may the top of a tree show when it should be felled ? At what time of year should trees be cut ?

Chapter II

8. The manufacture of lumber. — (A.) There are two distinct processes in the preparation of lumber for commercial purposes, logging and sawing ; the former includes

all the steps from felling the tree to the delivery of the logs at the sawmill; there the logs are sawed into boards, planks, and timbers of certain dimensions, which are piled and exposed to the sun and air for a sufficient time to allow a large part of the water in them to evaporate, when the lumber is said to be ''weather dried," and ready for shipment to the consumer.

W5

Fig. 4. — Felling a Tree.

(B.) If a lumber concern de.sii'es to begin operations in one of the great forest areas, a '' landlooker " or '' timbercruiser" is sent to spy out the land, and to report upon the probable yield of timber within certain areas, and the conditions which would aid or retard the work of getting out the logs. If the report is favorable, the standing timber may be purchased by

" stumpage," which means that a certain price will be paid for each thousand feet of lumber cut, or the land may be purchased outright, though in the early history of lumbering cases have been known where these little formalities were omitted.

Camps are located at convenient points throughout the boundary, roads are made through the woods, and foundations, or ''skidways," built at right angles to them, to receive the logs as they are hauled down the/'travoy" roads, which are narrow trails cut through the woods at frequent distances for this purpose.

(C.) The above preparations completed, the work of

Fig.

5. — Cutting Small Branches from Felled Spruce.

i'lG. (). SkIDWAY <)1' .Sl'KUCE LoGS

Fig. 7. — Load of White Pine Logs, felling the trees is begun (Fig. 4) ; this part of the work requires nice skill and judgment, as it is necessary that the tree should fall so that it will cause the least damage to itself and to surrounding trees. After the tree is down, the branches are cut close to the trunk (Fig. 5) and carried to one side so that they will not be in the way of the horses. The trunk is then sawed into logs, twelve, fourteen, sixteen, or eighteen feet in length, as the imperfections and the length of the tree trunk may allow.

Longer or shorter logs are rarely cut except for special purposes.

(D.) One end of the log is placed upon r. drag, or is gripped by a pair of tongs, and hauled to the nearest

travoy road and skidway, where it is piled (Fig. 6). (E.) From the skidway the logs are loaded upon trucks, cars, or sledges (Fig. 7), and carried to the cable (Fig. 8), which is a method of hauling logs used in some parts of the country, or to the railroad (Fig. 9), or floated down a river (Fig. 10). If either of these latter methods of

Fig. 8. — Hauling Logs by Steel Cable.

Fii. '.). — LoADiN i Logs from Shedway to Train.

Fig. 10. — Boom of Logs.

transportation is employed, the logs are generally piled upon another skidway until there is enough for a train load, or until the conditions upon the river are favorable for them to be floated to the mill.

(F.) Figure 11 illustrates a jam_ of logs, which is generally the most dangerous obstacle the lumberman has to face. A jam usually depends upon one key log, which, if loosened, will allow the jam to break instantly. The work of loosening the key log is frequently done by one or two men, who must be men of spring steel nerves and muscles, and possessed of the highest possible skill and activity, or they cannot hope to break a large jam and escape with their lives.

(G.) The mill illustrated by Fig. 12 is one which receives its logs by both rail and river. In this case the logs which come in by rail are rolled into the river, as they can be more easily placed upon the chain feed of the mill. In winter, a small pond of water is heated, in which the logs are soaked before they are taken into the

Fig. 12. — Sawmill in the Big Tree District.

mill ; this draws the frost out of them, and allows them to be worked much more easily:

(H.) There are different types of sawmills, in which the logs are worked into commercial shapes. The small enterprises use portable mills, which are moved into the woods and located upon a tract of land, remaining until all the desirable timber in the vicinity has been sawed, and then moved to another locality and the process repeated.

Large operations are conducted upon a different plan ; mills of a permanent type are erected as near the forest as practicable, roads are built, tracks laid, and the logs brought from the woods by one of the methods previously illustrated ; or, where it is feasible, flumes are built, and the logs floated in these to the mill. In erecting a mill of this sort, a location is selected upon a waterway if l^ossible, as the logs may be floated more cheaply than by any other method of transportation, though some of the heavier woods will not float, and have to be handled on land. (I.) The immersion of logs in water also improves the quality of the lumber, as the action of the water upon the sap prevents to some degree the tendency to decay, and also facilitates the seasoning of the manufactured product. If the log is left in the water until it becomes water-logged, it will sink, and while it is not injured for many purposes, the wood loses some of the strength which it is supposed to have. In many localities, the salvage of sunken logs has become an industry.

(J.) In modern large lumbering operations, the timber to be cut is selected by trained foresters, thus insuring a permanent supply, and in the near future all extensive lumbering operations will, beyond doubt, be conducted upon a scientific basis, as it is apparent that unless lumbering is carried on differently than it has been in the past, the supply for the future will be entirely inadequate for the demand.

(K.) In the smaller sawmills, the logs are usually sawed into lumber of various dimensions by a circular saw (Fig. 13) ; but in the larger mills, the band saw generally is used. Figure 14 illustrates a double cut band sawmill, in which it will be seen that the saw makes a cut each time the log is carried either way.

9. To saw lumber of irregular dimensions. — (A.) Besides sawing dimension timber, joists, scantlings, boards,

and planks of different thicknesses are sawed, as follows :

21'', 3^ 3|'',4''; and thicker, if desired.

(B.) If lumber is cut again from its original dimensions, it is said to be resawed. When boards or planks of the above dimensions are dressed on both sides, they will be about I!' thinner ; thus, a board sawed V thick will, when seasoned and dressed, be but J'', and a 2'' plank will be but 1 J" or If, though still classed by their sawed dimensions.

Thicker lumber than that -above-mentioned usually comes under the head of dimension timber, which is not used to the extent that it was formerly, as steel and concrete are replacing it upon heavy work.

If V^ boards are wanted, I4'' or " five quarter '' lumber is usually resawed to furnish it, and after resawing, is planed upon each side to the desired thickness. Boards

Fig. 13. — Circular Saw.

LUMBERING AXD VARIETIES OF WOOD for box stock and other special purposes are sometimes sawed as thin as Y^

(C.) The method of cutting a log illustrated by Fig. 15 is known as plain, slash, or bastard sawing, and is the cheapest way to cut logs, both as to time and waste. The log is first squared to secure a bed upon which it may

lie while being sawed, which also makes it unnecessary to run each board by the edging saw to straighten the edges. The slabs at a are sawed into boards as the log is squared, and the bark, or '^ live These make an inferior nearly all sap, but they a