Carpentry for Boys

J >> J. S. Zerbe >> Carpentry for Boys

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[Illustration: _Fig. 44._]

PREPARING A BOX JOINT.--In order to match a box joint for the inner end
of a table drawer, the first step is to select two work sides. One work
side will be the edge of the board, and the other the side surface of
the board, and on those surfaces we will put crosses, as heretofore
suggested.

[Illustration: _Fig. 45._]

[Illustration: _Fig. 46._]

[Illustration: _Fig. 47._]

FIRST STEPS.--Now lap together the inner surfaces of these boards (Y,
Z), so the ends are toward you, as shown in Fig. 45. Then, after
measuring the thickness of the boards to be joined (the thinnest, if
they are of different thicknesses), set your compasses, or dividers, for
1/4 inch, providing the boards are 1/2 inch thick, and, commencing at
the work edge of the board, step off and point, as at A, the whole width
of the board, and with a square make the two cross marks (B), using the
two first compass points (A), then skipping one, using the next two, and
so on.

[Illustration: _Fig. 48._]

[Illustration: _Fig. 49._]

[Illustration: _Fig. 50._]

When this is done, turn up the board Z (Fig. 46), so that it is at right
angles to the board Y, and so the outer surface of the board Z is flush
with the end of the board X, and with a sharp knife point extend the
lines B along with the grain of the wood on board Z, up to the cross mark
C. This cross mark should have been previously made and is located as
far from the end of the board Z as the thickness of the board Y.

We now have the marks for the outer surface of the board Z, and the end
marks of board Y. For the purpose of getting the angles of the end of
the board Z and the outer side of board Y, a cross line (D, Fig. 47) is
drawn across the board X near the end, this line being as far from the
end as the thickness of the board Z, and a vertical line (E) is drawn
midway between the two first cross marks (A).

Now, with your compass, which, in the meantime, has not been changed,
make a mark (F), and draw down the line (G), which will give you the
working angle at which you may set the bevel gage. Then draw down an
angle from each alternate cross line (A), and turn the bevel and draw
down the lines (H). These lines should all be produced on the opposite
side of the board, so as to assure accuracy, and to this end the edges
of the board also should be scribed.

CUTTING OUT THE SPACES.--In cutting out the intervening spaces, which
should be done with a sharp chisel, care should be observed not to cut
over the shoulder lines. To prevent mistakes you should put some
distinctive mark on each part to be cut away. In this instance E, H show
the parts to be removed, and in Fig. 48 two of the cutaway portions are
indicated.

When the end of the board Z is turned up (Fig. 49), it has merely the
longitudinal parallel lines B. The bevel square may now be used in the
same manner as on the side of the board Y, and the fitting angles will
then be accurately true.

This is shown in Fig. 50, in which, also, two of the cutaway parts are
removed.

TOOLS USED IN LAYING OUT TENONS AND MORTISES.--A sharp-pointed knife
must always be used for making all marks. Never employ an awl for this
work, as the fiber of the wood will be torn up by it. A small try square
should always be used (not the large iron square), and this with a
sharp-pointed compass and bevel square will enable you to turn out a
satisfactory piece of work.

The foregoing examples, carefully studied, will enable you to gather the
principles involved in laying off any work. If you can once make a
presentable box joint, so that all the dovetails will accurately fit
together, you will have accomplished one of the most difficult phases of
the work, and it is an exercise which will amply repay you, because you
will learn to appreciate what accuracy means.

CHAPTER VI

THE USES OF THE COMPASS AND THE SQUARE

THE SQUARE.--The square is, probably, the oldest of all tools, and that,
together with the compass, or dividers, with which the square is always
associated, has constituted the craftsman's emblem from the earliest
historical times. So far as we now know, the plain flat form, which has
at least one right angle and two or more straight edges, was the only
form of square used by the workman. But modern uses, and the development
of joinery and cabinet making, as well as the more advanced forms of
machinery practice, necessitated new structural forms in the square, so
that the bevel square, in which there is an adjustable blade set in a
handle, was found necessary.

THE TRY SQUARE.--In the use of the ordinary large metal square it is
necessary to lay the short limb of the square on the face of the work,
and the long limb must, therefore, rest against the work side or edge of
the timber, so that the scribing edge of the short limb does not rest
flat against the work. As such a tool is defective in work requiring
accuracy, it brought into existence what is called the try square,
which has a rectangular handle, usually of wood, into which is fitted at
one end a metal blade, which is at right angles to the edge of the
handle. The handle, therefore, always serves as a guide for the blade in
scribing work, because it lies flat down on the work.

THE T-SQUARE is another modification of the try square, its principal
use being for draughting purposes.

THE COMPASS.--The compass is one of the original carpenter's tools. The
difference between _compass_ and _dividers_ is that compasses have
adjustable pen or pencil points, whereas dividers are without adjustable
points. Modern work has brought refinements in the character of the
compass and dividers, so that we now have the bow-compass, which is,
usually, a small tool, one leg of which carries a pen or pencil point,
the two legs being secured together, usually, by a spring bow, or by a
hinged joint with a spring attachment.

PROPORTIONAL DIVIDERS.--A useful tool is called the proportional
dividers, the legs of which are hinged together intermediate the ends,
so that the pivotal joint is adjustable. By means of this tool the scale
of work may be changed, although its widest field of usefulness is work
laid off on a scale which you intend to reduce or enlarge
proportionally.

DETERMINING ANGLES.--Now, in order to lay out work the boy should know
quickly and accurately how to determine various angles used or required
in his work. The quickest way in which to learn this is to become
familiar with the degree in its various relations.

[Illustration: _Fig. 51._]

DEFINITION OF DEGREE.--A degree is not a measure, as we would designate
a foot or a pound to determine distance or quantity. It is used to
denote a division, space, interval or position. To illustrate, look at
the circle, Fig. 51. The four cardinal points are formed by the cross
lines (A, B), and in each one of the quadrants thus formed the circle is
divided into 90 degrees. Look at the radial lines (C, D), and you will
find that the distance between these lines is different along the
curved line (E) than along the curved line (F). The degree is,
therefore, to indicate only the space, division or interval in the
circle.

THE MOST IMPORTANT ANGLE.--Most important for one to know at a glance is
that of 45 degrees, because the one can the more readily calculate the
other degrees, approximately, by having 45 degrees once fixed in the
mind, and impressed on the visual image. With a square and a compass it
is a comparatively easy matter accurately to step off 45 degrees, as it
is the line C, midway between A and B, and the other degrees may be
calculated from the line C and the cardinal lines A or B.

DEGREES WITHOUT A COMPASS.--But in the absence of a compass and when you
do not wish to step off a circle, you will in such case lay down the
square, and mark off at the outer margin of the limbs two equal
dimensions. Suppose we take 2 inches on each limb of the square. The
angle thus formed by the angle square blade is 45 degrees. To find 30
degrees allow the blade of the angle square to run from 2 inches on one
limb to 3-1/2 inches on the other limb, and it will be found that for 15
degrees the blade runs from 2 inches on one limb to 7-1/2 inches on the
other limb. It would be well to fix firmly these three points, at least,
in your mind, as they will be of the utmost value to you. It is a
comparatively easy matter now to find 10 degrees or 25 degrees, or any
intermediate line.

WHAT DEGREES ARE CALCULATED FROM.--The question that now arises is what
line one may use from which to calculate degrees, or at what point in
the circle zero is placed. Degrees may be calculated either from the
horizontal or from the vertical line. Examine Fig. 53. The working
margin indicated by the cross mark is your base line, and in specifying
an angle you calculate it from the work edge. Thus, the line A indicates
an angle of 30 degrees. The dotted line is 45 degrees.

[Illustration: _Fig. 52._]

[Illustration: _Fig. 53._]

[Illustration: _Fig. 54._]

THE DIVIDERS.--The dividers are used not only for scribing circles, but
also for stepping and dividing spaces equally. There is a knack in the
use of the dividers, where accuracy is wanted, and where the surface is
of wood. Unless the utmost care is observed, the spaces will be unequal,
for the reason that the point of the dividers will sink more deeply into
the wood at some places than at others, due to the uneven texture of the
wood grain. It will be better to make a line lengthwise, and a cross
line (A) for starting (see Fig. 54). You may then insert one point of
the dividers at the initial mark (B), and describe a small arc (C). Then
move the dividers over to the intersection of the arc (C) on the line,
and make the next mark, and so on.

Some useful hints along this same line will be found under the chapter
on Drawing, which should be carefully studied.

CHAPTER VII

HOW THE DIFFERENT STRUCTURAL PARTS ARE DESIGNATED

THE RIGHT NAME FOR EVERYTHING.--Always make it a point to apply the
right term to each article or portion of a structure. Your explanation,
to those who do know the proper technical terms, will render much easier
a thorough understanding; and to those who do not know, your language
will be in the nature of an education.

PROPER DESIGNATIONS.--Every part in mechanism, every point, curve and
angle has its peculiar designation. A knowledge of terms is an
indication of thoroughness in education, and, as heretofore stated,
becomes really the basis of art, as well as of the sciences. When you
wish to impart information to another you must do it in terms understood
by both.

Furthermore, and for this very reason, you should study to find out how
to explain or to define the terms. You may have a mental picture of the
structure in your mind, but when asked to explain it you are lost.

LEARNING MECHANICAL FORMS.--Suppose, for example, we take the words
_segment_ and _sector_. Without a thorough understanding in your own
mind you are likely to confuse these terms by taking one for the other.
But let us assume you are to be called upon to explain a sector to some
one who has no idea of terms and their definitions. How would you
describe it? While it is true it is wedge-shaped, you will see by
examining the drawing that it is not like a wedge. The sector has two
sides running from a point like a wedge, but the large end of the sector
is curved.

If you were called upon to define a segment you might say it had one
straight line and one curve, but this would not define it very lucidly.
Therefore, in going over the designations given, not only fix in your
mind the particular form, but try to remember some particular manner in
which you can clearly express the form, the shape or the relation of the
parts.

For your guidance, therefore, I have given, as far as possible, simple
figures to aid you in becoming acquainted with structures and their
designations, without repeating the more simple forms which I have used
in the preceding chapters.

[Illustration: _Fig. 55.-Fig. 65._]

55. _Arcade._--A series of arches with the columns or piers which
support them, the spandrels above, and other parts.

56. _Arch._--A curved member made up, usually, of separate wedge-shaped
solids, A. K, Keystone; S, Springers; C, Chord, or span.

57. _Buttress._--A projecting mass of masonry. A, used for resisting the
thrust of an arch, or for ornamentation; B, a flying buttress.

58. _Chamfer._--The surface A formed by cutting away the arris or angle
formed by two faces, B, C, of material.

59. _Cotter or Cotter Pin._--A pin, A, either flat, square or round,
driven through a projecting tongue to hold it in position.

60. _Crenelated._--A form of molding indented or notched, either
regularly or irregularly.

61. _Crosses._--1. Latin cross, in the Church of Rome carried before
Bishops. 2. Double cross, carried before Cardinals and Bishops. 3.
Triple or Papal cross. 4. St. Andrew's and St. Peter's cross. 5. Maltese
cross. 6. St. Anthony or Egyptian cross. 7. Cross of Jerusalem. 8. A
cross patte or ferme (head or first). 9. A cross patonce (that is,
growing larger at the ends). 10. Greek cross.

62. _Curb Roof._--A roof having a double slope, or composed on each side
of two parts which have unequal inclinations; a gambrel roof.

63. _Cupola._--So called on account of its resemblance to a cup. A roof
having a rounded form. When on a large scale it is called a dome.

_Crown Post._--See _King Post_.

64. _Console._--A bracket with a projection not more than half its
height.

65. _Corbels._--A mass of brackets to support a shelf or structure.
Largely employed in Gothic architecture.

[Illustration: _Fig. 66.-Fig. 79._]

66. _Dormer._--A window pierced in a roof and so set as to be vertical,
while the roof slopes away from it. Also called a _Gablet_.

67. _Dowel._--A pin or stud in one block, or body, designed to engage
with holes in another body to hold them together in alignment.

68. _Drip._--That part of a cornice or sill course A, or other
horizontal member which projects beyond the rest, so as to divert water.

69. _Detents._--Recesses to lock or to serve as a stop or holding place.

70. _Extrados._--The exterior curve of an arch, especially the upper
curved face A. B is the _Intrados_ or _Soffit_.

71. _Engrailed._--Indented with small concave curves, as the edge of a
bordure, bend, or the like.

72. _Facet._--The narrow plain surface, as A, between the fluting of a
column.

73. _Fret, Fretwork._--Ornamental work consisting of small fillets, or
slats, intersecting each other or bent at right angles. Openwork in
relief, when elaborated and minute in all its parts. Hence any minute
play of light and shade. A, Japanese fretwork. B, Green fret.

74. _Frontal_, also called _Pediment_.--The triangular space, A, above a
door or window.

75. _Frustums._--That part of a solid next the base, formed by cutting
off the top; or the part of any solid, as of a cone, pyramid, etc.,
between two planes, which may either be parallel or inclined to each
other.

76. _Fylfat._--A rebated cross used as a secret emblem and worn as an
ornament. It is also called _Gammadium_, and more commonly known as
_Swastika_.

77. _Gambrel Roof._--A curb roof having the same section in all its
parts, with a lower, steeper and longer part. See _Curb Roof_ and
distinguish difference.

78. _Gargoyle._--A spout projecting from the roof gutter of a building,
often carved grotesquely.

79. _Gudgeon._--A wooden shaft, A, with a socket, B, into which is
fitted a casting, C. The casting has a _gudgeon_, D.

[Illustration: _Fig. 80.-Fig. 93._]

80. _Guilloche._--An ornament in the form of two or more bands or
strings twisted together or over or through each other.

81. _Half Timbered._--Constructed of a timber frame, having the spaces
filled in with masonry.

82. _Hammer Beam._--A member of one description of roof truss, called
hammer-beam truss, which is so framed as not to have a tie beam at the
top of the wall. A is the _hammer beam_, and C the pendant post.

83. _Haunches._--The parts A, A, on each side of the crown of an arch.
Each haunch is from one-half to two-thirds of the half arch.

84. _Header._--A piece of timber, A, fitted between two trimmers, B, B,
to hold the ends of the tail beams, C, C.

85. _Hip Roof._--The external angle formed by the meeting of two sloping
sides or skirts of a roof which have their wall plates running in
different directions.

86. _Hood Molding._--A projecting molding over the head of an arch, as
at A, forming the outer-most member of the archivolt.

87. _Inclave._--The border, or borders, having a series of dovetails.
One variation of molding or ornamentation.

88. _Interlacing Arch._--Arches, usually circular, so constructed that
their archivolts, A, intersect and seem to be interlaced.

89. _Invected._--Having a border or outline composed of semicircles or
arches, with the convexity outward. The opposite of engrailed.

90. _Inverted Arch._--An arch placed with the crown downward; used in
foundation work.

91. _Keystone._--The central or topmost stone, A, of an arch, sometimes
decorated with a carving.

92. _King Post._--A member, A, of a common form of truss for roofs. It
is strictly a tie intended to prevent the sagging of the tie beam, B, in
the middle. If there are struts, C, supporting the rafters, D, they
extend down to the foot of the _King Post_.

93. _Label._--The name given to the projecting molding, A, around the
top of the door opening. A form of mediaeval architecture.

[Illustration: _Fig. 94.-Fig. 104._]

94. _Louver._--The sloping boards, A, set to shed rain water outward in
an opening of a frame, as in belfry windows.

95. _Lintel._--A horizontal member. A spanning or opening of a frame,
and designed to carry the wall above it.

96. _Lug._--A. projecting piece, as A, to which anything is attached, or
against which another part, like B, is held.

97. _M-Roof._--A kind of roof formed by the junction of two common roofs
with a valley between them, so the section resembles the letter M.

98. _Mansard Roof._--A hipped curb roof, that is, a roof having on all
sides two slopes, the lower one, A, being steeper than the upper portion
or deck.

99. _Newel Post._--The upright post at the foot of a stairway, to which
the railing is attached.

100. _Parquetry._--A species of joinery or cabinet work, consisting of
an inlay of geometric or other patterns, generally of different colored
woods, used particularly for floors.

101. _Peen._ also _Pein._--The round, _round_-edged or hemispherical
end, as at A, of a hammer.

102. _Pendant._--A hanging ornament on roofs, ceilings, etc., and much
used in the later styles of Gothic architecture where it is of stone.
Imitated largely in wood and plaster work.

103. _Pentastyle._--A pillar. A portico having five pillars, A, is
called the _Pentastyle_ in temples of classical construction.

104. _Pedestal._--An upright architectural member, A, right-angled in
plan, constructionally a pier, but resembling a column, having a
capital, shaft and base to agree with the columns in the structure.

[Illustration: _Fig. 105.-Fig. 117._]

105. _Pintle._--An upright pivot pin, or the pin of a hinge; A
represents the _pintle_ of a rudder.

106. _Portico._--A colonnade or covered structure, especially in
classical style, of architecture, and usually at the entrance of a
building.

107. _Plate._--A horizontal timber, A, used as a top or header for
supporting timbers, roofs and the like.

108. _Queen Post._--One of two suspending posts in a roof truss, or
other framed truss of simple form. Compare with _King Post._ A, B, tie
beam; C, C, queen posts; D, straining piece; E, principal rafter; F,
rafter.

109. _Quirk Molding._--A small channel, deeply recessed, in proportion
to its width, used to insulate and give relief to a convex rounded
molding. An excellent corner post for furniture.

110. _Re-entering._--The figure shows an irregular polygon (that is,
many-sided figure) and is a re-entering polygon. The recess A is a
re-entering angle.

111. _Rafter._--Originally any rough and heavy piece of timber, but in
modern carpentry used to designate the main roof support, as at A. See
_Queen Post_.

112. _Scarfing._--Cutting timber at an angle along its length, as the
line A. Scarfing joints are variously made. The overlapping joints may
be straight or recessed and provided with a key block B. When fitted
together they are securely held by plates and bolts.

113. _Scotia Molding._--A sunken molding in the base of a pillar, so
called from the dark shadow which it casts.

114. _Sill._--In carpentry the base piece, or pieces, A, on which the
posts of a structure are set.

115. _Skew-Back._--The course of masonry, such as a stone, A, with an
inclined face, which forms the abutment for the voussoirs, B, or
wedge-shaped stones comprising the arch.

116. _Spandrel._--The irregular, triangular space, A, between the curve
of an arch and the enclosing right angle.

117. _Strut._--In general, any piece of a frame, such as a timber A, or
a brace B, which resists pressure or thrust in the direction of its
length.

[Illustration: _Fig. 118.-Fig. 123._]

118. _Stud, Studding._--The vertical timber or scantling, A, which is
one of the small uprights of a building to which the boarding or
plastering lath are nailed.

119. _Stile._--The main uprights of a door, as A, A; B, B, B, rails; C,
C, mullions; D, D, panels.

_Tie Beam._--See _Queen Post_.

120. _Trammel._--A very useful tool for drawing ellipses. It comprises a
cross, A, with grooves and a bar, B, with pins, C, attached to sliding
blocks in the grooves, and a pen or stylus, D, at the projecting end of
the bar to scribe the ellipse.

121. _Turret._--A little tower, frequently only an ornamental structure
at one of the angles of a larger structure.

122. _Transom._--A horizontal cross-bar, A, above a door or window or
between a door and a window above it. Transom is the horizontal member,
and if there is a vertical, like the dotted line B, it is called a
_Mullion_. See _Stile_.

123. _Valley Roof._--A place of meeting of two slopes of a roof which
have their sides running in different directions and formed on the plan
of a re-entrant angle.

CHAPTER VIII

DRAWING AND ITS UTILITY

A knowledge of drawing, at least so far as the fundamentals are
concerned, is of great service to the beginner. All work, after being
conceived in the brain, should be transferred to paper. A habit of this
kind becomes a pleasure, and, if carried out persistently, will prove a
source of profit. The boy with a bow pen can easily draw circles, and
with a drawing or ruling pen he can make straight lines.

REPRESENTING OBJECTS.--But let him try to represent some object, and the
pens become useless. There is a vast difference in the use of drawing
tools and free-hand drawing. While the boy who is able to execute
free-hand sketches may become the better artist, still that art would
not be of much service to him as a carpenter. First, because the use of
tools gives precision, and this is necessary to the builder; and,
second, because the artist deals wholly with perspectives, whereas the
builder must execute from plane surfaces or elevations.

FORMING LINES AND SHADOWS.--It is not my intention to furnish a complete
treatise on this subject, but to do two things, one of which will be to
show, among other features, how simple lines form objects; how shading
becomes an effective aid; how proportions are formed; and, second, how
to make irregular forms, and how they may readily be executed so that
the boy may be able to grasp the ideas for all shapes and structural
devices.

[Illustration: _Fig. 125._]

[Illustration: _Fig. 126._]

[Illustration: _Fig. 127._]

ANALYSIS OF LINE SHADING.--In the demonstration of this work I shall
give an analysis of the simple lines formed, showing the terms used to
designate the lines, curves, and formations, so that when any work is
laid out the beginner will be able, with this glossary before him, to
describe architecturally, as well as mathematically, the angles and
curves with which he is working.

HOW TO CHARACTERIZE SURFACE.--Suppose we commence simply with straight
lines. How shall we determine the character of the surface of the
material between the two straight lines shown in Fig. 125? Is it flat,
rounded, or concaved? Let us see how we may treat the surface by simple
lines so as to indicate the configuration.

[Illustration: _Fig. 128._]

[Illustration: _Fig. 129._]

[Illustration: _Fig. 130._]

[Illustration: _Fig. 131._]

CONCAVE SURFACES.--In Fig. 126 the shading lines commence at the upper
margin, and are heaviest there, the lines gradually growing thinner and
farther apart.

CONVEX SURFACES.--In Fig. 127 the shading is very light along the upper
margin, and heavy at the lower margin. The first shaded figure,
therefore, represents a concaved surface, and the second figure a
convex surface. But why? Simply for the reason that in drawings, as well
as in nature, light is projected downwardly, hence when a beam of light
moves past the margin of an object, the contrast at the upper part,
where the light is most intense, is strongest.

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