1. LAYING OUT DUPLICATE PARTS. 2. SCRAPING AND SANDPAPERING. 3.
FASTENING PARTS.
=62. Laying out Duplicate Parts.=--Frequently a piece of work will
require the making of two or more like parts. To lay out these parts,
that is, to mark out the location of intended gains, mortises,
shoulders of tenons, etc., so that all shall be alike, the following
method is used: (1) On the face edge of one of the pieces measure off
with the rule and mark with knife the points at which the lines for
the joints are to be squared across. If knife marks would show on the
finished surface as scratches, use a sharp pencil instead. (2) Lay the
pieces on the bench top with the face edges up; even the ends with the
try-square. Fig. 117. Square lines across the edges of all of them at
the points previously marked on one of them. The pieces may then be
separated and lines corresponding to the lines just made on the face
edges, be carried across the face sides of each piece separately, the
try-square beam being held against the face edge in so doing, of course.
[Illustration: FIG. 117.]
In all duplicate work the aim of the worker should be to make as much
use as possible of the tool he has in hand before laying it down and
taking another. To illustrate, if there should be a number of like
parts each requiring two different settings of the gage, he should mark
all of the parts at the first setting, then all at the second setting
rather than to change the gage for each piece so that each piece might
be completely marked before another is begun.
=63. Scraping.=--In smoothing hard wood surfaces, a scraper will be
found helpful. If the grain should happen to be crossed or curled, a
scraper will become a necessity. The plane-iron may be made ever so
sharp and the cap-iron set ever so close to the cutting edge, still the
surface of some woods will tear. Sandpaper must not be depended upon to
smooth a torn surface.
[Illustration: FIG. 118.]
Cabinet scrapers for plane and convex surface work are rectangular
pieces of saw steel. Fig. 118 shows a swan-neck scraper suitable for
smoothing concave surfaces.
Beginners frequently mistake surfaces which have been planed at a mill
for smooth surfaces. They are not; and, unless the “hills and hollows”
which extend across the surface of every mill-planed piece of lumber
are removed before the finish of stain or filler is applied, the result
will be very unsatisfactory.
These “hills and hollows” are present even in the smoothest of
mill-plane surfaces. The reason is easily understood. When a board is
mill-planed, it is run through a machine which has a flat bed over
which the board is moved and above which revolve two knives. Fig. 119.
Unless the grain of wood is very badly crossed or curled, it will be
found very much easier, and time will be saved if the mill marks are
removed with a smooth-plane before the scraper is applied.
[Illustration:
A--Delivery Roller.
B--Cutter Head.
C--Feed Roller.
D--Roller.
E--Roller.
F--Board.
G--Work Table.
H--Knives.
FIG. 119.]
Scrapers may be pushed or pulled. Fig. 120. When properly sharpened
thin silky shavings will be cut off. The cutting edge of a scraper is a
bur which is formed at an arris and turned at very nearly a right angle
to the surface of the scraper.
[Illustration: FIG. 120.]
[Illustration: FIG. 121.]
When a scraper becomes dull (1) each edge is drawfiled, Fig. 121, so
as to make it square and straight, with the corners slightly rounded.
Sometimes the edges are rounded slightly from end to end to prevent
digging. Frequently the scraper has its edges and surfaces ground
square on an oilstone after the drawfiling that the arrises may be
formed into smoother burs. (2) After filing, the scraper is laid flat
on the bench and the arrises forced over as in Fig. 122. The tool used
is called a burnisher; any smooth piece of steel would do. (3) Next,
turn these arrises back over the side of the scraper. Fig. 123. Great
pressure is not necessary to form the burs properly.
[Illustration: FIG. 122.]
[Illustration: FIG. 123.]
=64. Sandpapering.=--To know when to use and when not to use sandpaper
is as much the sign of a good workman as to know how to use the tools.
Sandpaper should never be used until all tool work has been done as
well, and carried as far as is possible. Sandpaper is, as its name
implies, sand paper. In sanding a surface, this fine sand becomes
imbedded in the wood and should an edged tool be used thereon it will
be dulled. Slovenly work should never be done in expectation of using
sandpaper to fix it up. This practice is dishonest. Sandpaper should
not be expected to do the work of edged tools or disappointment will
follow. The sandpaper sheet, for use, is usually divided into four
parts, one of these parts being of good size for large work.
[Illustration: FIG. 124.]
For flat surfaces these pieces are placed on a sandpaper block. This
block is but a piece of wood squared up to a length equal to that of
the piece of paper and to such a width that the edges of the paper
will extend far enough up the edges of the block to allow the fingers
to grasp them firmly. Fig. 124. Do not waste the paper by wrapping
it around in such a way as to throw part of it on top of the block.
The block should be held flat upon the surface when sanding near an
arris, otherwise the arris will be rounded. The arrises should be kept
sharp unless on a table leg, arm of a chair or something similar, in
which the sharp arrises would be likely to injure the hand or become
splintered through usage. In such cases the sandpaper may be run
along the arrises once or twice, just enough to remove the sharpness.
Sometimes the plane is set shallow and drawn over the arris after the
surfaces have been squared, to remove the sharpness.
On curved surfaces, the sandpaper is held free in the hand, no block
being used. Fig. 115 illustrates the manner of sanding the convex curve
of the coat hanger. The sandpaper should be rubbed along the grain and
the rubbing should proceed only long enough to smooth the piece and to
bring out the grain clearly.
On the back of a piece of sandpaper will be found a number. This number
indicates the relative coarseness of the sand sprinkled upon the glue
covered paper. 00, 0, 1, 1¹⁄₂ and 2 are the numbers commonly used; 00
being finest and 2 relatively coarse. On table tops and surfaces which
are not very smooth to begin with, the coarse sandpaper is first used,
this is followed by the next in coarseness and so on until the finest
is used.
Never attempt to sandpaper surfaces or parts which are to be put
together later on to form joints, the edge tools alone must be depended
upon to secure proper smoothing.
=65. Hammers.=--Fig. 125 shows the two kinds of hammers most commonly
used by workers in wood. The plain faced hammer has a flat face and
is somewhat easier to learn to use than the bell-faced hammer, which
has a slightly rounded face. The advantage of the bell-faced hammer
lies in one’s ability to better set a nail slightly below the surface
without the assistance of the nailset. This is a very great advantage
on outside or on rough carpenter work. This setting of the nail with
the hammer leaves a slight depression, however, in the wood, and is
therefore not suited for inside finishing.
[Illustration: FIG. 125.]
The handle of the hammer is purposely made quite long and should be
grasped quite near the end.
=66. Nails.=--Nails originally were forged by hand and were therefore
very expensive. Later strips were cut from sheets of metal and heads
were hammered upon these by means of the blacksmith’s hammer, the vise
being used to hold the strips meanwhile. These were called cut nails.
Early in the nineteenth century a machine was invented which cut the
nails from the sheet metal and headed them.
Steel wire nails have about supplanted the cut nails for most purposes.
They are made by a machine which cuts the wire from a large reel,
points and heads the pieces thus cut off.
Wire nails, like cut nails, are roughly classed by woodworkers as
common, finishing and casing nails. Thin nails with small heads are
called brads. Wire nails are bought and sold by weight, the size of
wire according to the standard wire gage and the length in inches being
taken into consideration in specifying the size and fixing the price
per pound.
In former practice, the size of nails was specified according to the
number of pounds that one thousand of any variety would weigh. Thus
the term sixpenny and eightpenny referred to varieties which would
weigh six and eight pounds per thousand, respectively, penny being
a corruption of pound. In present practice, certain sizes are still
roughly specified as three, four, six, eight, ten, twenty and thirty
penny.
[Illustration: FIG. 126.]
Common wire nails are thick and have large flat heads. They are used in
rough work where strength is desired. Fig. 126 A. Finishing nails, Fig.
126 B, are used for fine work such as inside woodwork, cabinet work,
etc. Casing nails, Fig. 126 C, are somewhat thicker and stronger than
finishing nails; they have small heads.
=67. Nailing.=--Especial care is necessary in starting cut nails. Fig.
127 shows two views of a cut nail. From these it will be seen that the
sides of the nail form a wedge in one of the views while in the other
they are parallel. The nail should be so started that the wedging
action shall take place along, not across the grain.
[Illustration: FIG. 127.]
[Illustration: FIG. 128.]
In nailing through one piece into the edge of another, assume a
position so that you can look along the piece into the edge of which
you are nailing. Fig. 128. If the nail is to be driven plumb, it must
be sighted from two directions several times in the beginning of the
nailing. Having driven the points of the nails slightly below the
surface of the first piece, adjust the two pieces properly, force the
points into the second piece, and, holding the parts firmly with the
left hand, drive the nails into place.
=68. Nailset.=--Except in rough work, the nail should not be driven
entirely in with the hammer or the wood will be marred. A nailset held
as in Fig. 129 should be used to set the head of the nail slightly
below the surface of the wood--about one thirty-second of an inch. A
finger placed against the side of the nailset and allowed to rest on
the piece of wood aids greatly in guiding the set, which otherwise
might jump off the nail head when the blow is struck and indent the
wood.
[Illustration: FIG. 129.]
[Illustration: FIG. 130.]
=69. Withdrawing Nails.=--Should it be necessary to withdraw a nail,
place a block of wood under the head of the hammer, Fig. 130, to
prevent marring the surface of the wood. If the nail is a long one, the
size of the block used should be increased as the nail comes out, that
the nail may not be bent.
=70. The Screwdriver.=--Patent ratchet and spiral screwdrivers have
come into quite common use among workers in wood. The old style, Fig.
131, however, is much better suited to elementary work than any of
these special forms.
[Illustration: FIG. 131.]
=71. Screws.=--Screws, like nails, are made entirely by machinery. They
are packed in pasteboard boxes and sold by the gross. The size of a
screw is designated by the length in inches and the size of the wire
from which it is made; thus, 1 inch No. 10 flat-head bright screw.
The gage of wire for nails and the gage of wire for screws should not
be confused. Fig. 132 is a full-sized illustration of the gage used
for determining the size of wire for nails. The numbers apply to the
openings at the edge, not to the circular parts. The notch at No. 1
will just slip over No. 1 wire. Fig. 135 is a full-sized illustration
of a wire gage for screws. The gage is slipped over the screw just
below the head.
[Illustration: FIG. 132.]
Flathead screws are used for ordinary work. Roundhead screws are used
because they are more ornamental. Fig. 133. Either kind may be made of
steel or brass. Steel screws are often blued by treating them with heat
or an acid.
[Illustration: FIG. 133.]
[Illustration: FIG. 134.]
=72. Fastening with Screws.=--Where two pieces of hard wood are to be
fastened with screws, a hole just large enough to take in the shank of
the screw must be bored in the upper part. In the lower part, a hole
should be bored just large enough to take in the core of the screw
snugly. Fig. 134. For flathead screws, the hole should be countersunk
so that the head may be flush or sunk slightly below the surface of the
wood. In soft woods, the boring of a hole in the lower piece may be
omitted.
[Illustration: FIG. 135.]
=73. Glue.=--Nails are but seldom used in cabinet work to fasten parts
together; glue being used instead. Glue is manufactured from the refuse
parts of animals. Strippings of hide, bone, horn, hoofs, etc., are
boiled to a jelly; chemicals are added to give it the light color. It
is usually placed on the market in the form of dry chips.
Glue pots are made double, the glue being placed in one part and this
placed in a larger one which contains water.
[Illustration: FIG. 136.]
The glue is heated by the hot water and steam of the outer kettle. Fig.
136.
To prepare glue, dissolve the dry chips in water. It is well to soak
them over night unless quite thin. If the glue chips are thin they may
be barely covered with water and the pot set in the outer kettle of
boiling water. Some kinds of glue require less water. The glue should
be stirred occasionally. It should be used while hot and should be made
thin enough to flow easily when applied with a brush. If the wood is
cold it will chill the glue. Best results are obtained by warming the
wood in an oven.
Prepared liquid glues, to be applied without heating, are common. As
these glues thicken with age, due to evaporation, they must be thinned
occasionally. In cold weather they chill and must be warmed in hot
water to bring them to a proper consistency.
[Illustration: FIG. 137.]
=74. Clamps.=--Clamps are used in the making of a glue joint to expel
the glue from the surfaces of contact, forcing it up into the pores
of the wood or, if too much has been applied, out on the sides of the
joint. For holding small parts, the wooden hand-screw is used, Fig.
137. To adjust this clamp, hold the handle of the shoulder spindle
firmly in the left hand and the handle of the end spindle in the right
hand; revolve them about an axis midway between and parallel to the
spindles until the approximate opening of the jaw is obtained, Fig.
138. Place the clamp on the parts and screw the shoulder spindle up
tight, adjusting the end spindle when necessary so that when it is
tightened the jaws of the clamp shall be parallel, Fig. 139. In taking
off this clamp, the end spindle is the one which must be released.
[Illustration: FIG. 138.]
[Illustration: FIG. 139.]
Fig. 140 illustrates three kinds of bar clamps such as are used for
clamping wide frames and boards.
[Illustration: FIG. 140.]
Fig. 141 illustrates a simple form of clamp which can be made by the
student himself. Two wedges to each clamp, driven in with the hammer,
supply the necessary pressure. Whenever finished surfaces are to be
clamped, blocks of wood must be placed between them and the clamp jaws
to prevent their being marred.
[Illustration: FIG. 141.]
=75. Gluing.=--Where the end grain is to form part of a glue joint, it
is necessary to apply a glue size first.
This is done by filling the open grain of the end with a preliminary
coating of thin, hot glue.
Rubbed glue joints require no clamps. The edges are jointed perfectly
straight, glue is applied to each and they are then rubbed together
with as great pressure as is possible to expel the glue. When this is
properly done the pieces will hold together and may be set away to dry.
Fig. 142.
[Illustration: FIG. 142.]
PART II.
SIMPLE JOINERY.
CHAPTER VIII.
TYPE FORMS.
=76. Joinery.=--This term in its broader meaning refers to the art of
framing the finishing work of a house, such as doors and windows; and
to the construction of permanent fittings, such as mantels, cupboards,
linen presses, etc. Joinery as used herein refers merely to the putting
together of two or more parts, called the members.
=77. General Directions for Joinery:=--Take into consideration
the direction of the grain in planning the relative positions of
the members. Make due allowance where shrinkage is likely to be
considerable.
As far as possible, plan to have the members join face to face. Face
sides are more likely to be true than are the other two surfaces and
therefore the joints are more likely to fit properly.
Make all measurements from a common starting point, as far as
practicable. Remember to keep the head of the gage, and the beam of the
trysquare against one or the other of the faces, unless there should be
special reasons for doing otherwise.
In practice it is sometimes advisable to locate the sides of a joint by
superposition rather than by measurement. Laying out by superposition
consists in placing one member upon another and marking upon the second
member the width, thickness or length of the first. Fig. 143. Usually,
it is found possible to locate and square with knife and trysquare a
line to represent one of the sides of the joint. The first member is
then held so that one of its arrises rests upon this line, and a point
is made with knife at the other arris. The superimposed piece is then
removed and a line made with knife and try-square--not thru the mark of
the knife point but inside, just touching it.
[Illustration: FIG. 143.]
[Illustration: FIG. 144.]
Where several members or parts are to be laid out, cut and fitted,
it is of the utmost importance that the work be done systematically.
System and power to visualize--that is, to see things in their proper
relation to one another in the finished piece--make it possible for
men to lay out and cut the members to the most intricate frames of
buildings before a single part has been put together. Lay out duplicate
parts and duplicate joints as suggested in Chapter VII, Section 62.
Where several joints of a similar size and kind are to be fitted, mark
the different parts to each joint with the same number or letter as
soon as fitted that no other member may be fitted to either of these.
Fig. 144. On small pieces, such as the stool, it is possible to aid in
visualizing by setting up the posts in the positions they are to occupy
relative to one another, marking roughly, as with a penciled circle,
the approximate location of the mortises, auger holes, etc. The members
may then be laid on the bench and accurately marked without danger of
misplacing the openings.
While the knife is used almost exclusively in laying out joints, there
are a few instances in which a pencil, if well sharpened and used with
slight pressure is preferable. To illustrate, suppose it is desired
to locate the ends of the mortises in the posts. Fig. 144. To knife
entirely across the surfaces of the four pieces and around the sides of
each as would be necessary to locate the ends of the mortises, would
injure the surfaces. Instead, pencil these lines and gage between the
pencil lines. Those parts of the pencil lines enclosed by the gage
lines--the ends of the mortises--may then be knifed, if desired, to
assist in placing the chisel for the final cut.
In sawing joints in hard wood, the saw should be made to cut accurately
to the line, Chapter II, Section 14. When working soft wood, beginners
are often permitted to leave a small margin--about one thirty-second of
an inch--between the knife and the saw kerf. This margin is afterwards
pared away with the chisel.
[Illustration: FIG. 145.]
[Illustration: FIG. 146.]
=78. Dado.=--A dado, Fig. 145, is made by cutting a rectangular groove
entirely across one member into which the end of another member fits.
Dadoes are cut across the grain of the wood; when similar openings are
cut parallel to the grain, they are called simply, grooves. Dadoes are
used in the making of shelving, window and door frames, etc.
=79. Directions for Dado.=--(1) Locate by means of the rule one side of
the dado and mark its position with the point of the knife. (2) At this
point, square a sharp line across the piece with knife and trysquare.
(3) By superposition, locate and mark the second side. (4) Square these
lines across the edges of the piece a distance equal to the approximate
depth of the dado. (5) Set the gage for the required depth and gage
between the knife lines on the two edges. (6) Saw just far enough
inside the knife lines that the sides of the dado may be finished to
the lines with the chisel. Chapter II, Section 14. Saw down just to
the gage lines, watching both edges that the kerfs be not made too
deep. (7) Chisel out the waste until the bottom of the dado is smooth
and true. Chapter V, Section 47. Test the bottom as shown in Fig. 146.
Two brads are driven into a block having a straight edge until they
project a distance equal to the proposed depth of the dado. (8) Pare
the sides of the dado to the knife lines. Chapter V, Section 48. These
sides might be finished in another way, by setting a wide chisel in the
knife line and tapping it gently with a mallet. If care is taken the
successive settings of the chisel need not show.
Where the dado is to be cut on a piece narrow enough that the saw may
be made to follow the line accurately, it is considered better practice
to saw accurately to the line. Chapter II, Section 14.
=80. Cross-Lap Joint.=--Usually, stock for the two members of the
cross-lap joint can be best planed to width and thickness in one piece.
Place two sets of face marks on the piece, so that there shall be one
set of marks on each member after they are separated. Two methods
of making this joint are given. The first is safer for beginners;
the second, because the members cannot be tried until the joints are
completed, is an excellent test of one’s ability. Fig. 147.
[Illustration: FIG. 147.]
=81. Directions for Cross-Lap Joint.=--_First Method_: (1) Square the
two ends, measure from each of these the desired length of each member,
square knife lines around, saw apart, finishing the ends square to the
lines. (2) Measure from one end of each member the required distance
to the nearer edge of the joint. Since the corresponding faces of the
two members must be on the same side of the piece when the parts are
put together, it will be necessary to lay off the groove of one member
on the face and of the other member on the side opposite the face. If
the joints are to be in the middle of each member but one measurement
need be made. Chapter VII, Section 62. (3) Square sharp knife lines
across at these points. (4) By superposition, locate and knife the
second edge of each joint. (5) If the joints are to be in the middle of
each member, before proceeding further, test to see that the lines have
been laid out properly. If the members are placed side by side and the
ends evened as in laying out in (2) above, the lines will of necessity
correspond. Turn one of the members end for end and even the two ends;
the lines ought still to correspond. If they do not, points marked
midway between the corresponding lines will give the correct position
for the new lines, Fig. 148. (6) Extend the knife lines just made
across the two adjoining surfaces of each member. (7) Set the gage for
the required depth and gage between the knife lines on these surfaces.
Tho the groove on one member is laid out on the side opposite the face,
do not make the mistake of holding the head of the gage against other
than the face. (8) Saw accurately, Chapter II, Section 14, to the knife
lines and to a depth indicated by the gage lines. (9) Chisel out the
waste stock. Chapter V, Section 47. (10) Test as shown in Fig. 149.
A well made cross-lap joint is one in which the members can be put
together with the pressure of the hands and which will not fall apart
of their own weight. Fig. 150 shows the results of “forcing a fit.”
[Illustration: FIG. 148.]
[Illustration: FIG. 149.]
[Illustration: FIG. 150.]
=82. Directions for Cross-Lap Joint.=--_Second Method._ The two members
are to be planed to width and thickness in one piece but are not
to be separated until the grooves have been laid out and cut. The
grooves must be laid out by measurement only, since superposition is
impossible. The positions of the grooves relative to the faces are, as
in the first method, one on the face and one on the side opposite. The
gaging for both is done from the faces.
=83. Glue Joint.=--Frequently it becomes necessary to glue together a
number of boards to make one wide enough to meet the requirements of
the work in hand. A table top is a good illustration. A properly glued
butt joint ought to be stronger than the natural wood.
When the wood is of sufficient thickness, the joint may be reinforced
by means of dowels. The jointer should be used for planing the edges.
It is extremely difficult to prepare edges for glue joints with the
shorter planes. The jack plane should be used to rough off the edges
and prepare them for the jointer.
[Illustration: FIG. 151.]
=84. Directions for Glue Joint.=--(1) If the boards are in the rough,
plane one surface of each true and out of wind. (2) Pencil the face
marks upon these surfaces and indicate in some way the direction of
the surface grain as well. Later, it will be necessary to plane both
pieces at once in surfacing over the joints, and unless the parts are
fitted with proper regard to the grain, it will be impossible to plane
one without roughing up the other. Then too, the faces should be so
selected that the warpage of one shall counteract the warpage of the
other. Fig. 151 shows the manner of placing the pieces. Observe the
rings of growth. Chapter 12. (3) Joint one edge of each piece straight
and square. The final plane strokes must be taken the full length
of the board and the plane-iron must be set very shallow. Since the
shrinkage is more at the ends than in the middle, sometimes the middles
of long boards are planed just a shaving or two lower than the ends.
(4) Place one of the boards in the vise, jointed edge up, and place the
other board in position on it. Four tests are commonly used: First,
placing the eye on a level with the joint and looking toward the light,
Fig. 152; second, tapping the under board lightly to see if the top
board “rocks”; third, sliding the top board lengthwise slowly to “feel”
for suction; fourth, holding a straightedge as shown in Fig. 153 to see
that the faces lie in the same plane. (5) Glue the edges, Fig. 154.
Work rapidly but carefully. (6) Place the parts in the clamps and set
away to dry; ten hours is usually long enough. Keep the faces as even
as possible in applying the clamps. (7) When the glue has hardened
the clamps may be removed, the surplus glue scraped off and the parts
treated as one piece in squaring it up.
[Illustration: FIG. 152.]
[Illustration: FIG. 153.]
[Illustration: FIG. 154.]
=85. Doweling.=--Dowels are small wooden pins used in joining
parts together. Dowels can be bought ready made in a variety of
sizes. If desired short dowels may be made as follows: (1) Select
straight-grained strong wood--beech, birch or oak; waste wood can
usually be found that will do. (2) Split, not saw, these pieces roughly
to square prisms. The blocks from which they are to be split should
not be over eight or ten inches long to work well. (3) Plane off the
irregularities, roughly rounding the pieces to size. (4) Point the ends
slightly and drive the pieces thru a dowel plate. Fig. 155. The pegs
should be driven thru the larger hole first. The holes of the dowel
plate are larger in diameter on one side of the plate than on the other
to give clearance to the peg as it is driven thru.
[Illustration: FIG. 155.]
The cutting edge of the hole is at the smaller diameter; place that
side of the plate up. Never use a hammer as it would split the top of
the peg and would ruin the cutting edge of the dowel plate should it
strike it. Use a mallet, and when the peg is nearly thru finish by
striking a second peg placed upon the head of the first.
=86. Directions for Doweling.=--(1) Place the boards to be doweled side
by side in the vise, the face sides out, and even the jointed edges.
(2) Square lines across the two edges with knife and trysquare at
points where it is desired to locate dowels. (3) Set the gage for about
half the thickness of the finished board and gage from the face side
across the knife lines. (4) At the resulting crosses bore holes of the
same diameter as that of the dowel.
[Illustration: FIG. 156.]
These holes should be bored to a uniform depth. Count the turns of the
brace. One inch is a good depth for ordinary work. (5) Countersink the
holes slightly, just enough to remove the sharp arrises. This removes
any bur and allows a little space into which the surplus glue may run.
(6) Cut the sharp arrises off the dowel, just enough to allow it to be
started into the hole. (7) With a stick slightly smaller than the hole,
place glue upon the sides of the hole, and drive the dowel in. A small
V-shaped groove previously cut along the side of the dowel will allow
the surplus glue to escape and thus prevent any danger of splitting the
board. (8) Clean off the surplus glue, unless the members can be placed
together before it has had time to set. (9) Saw off the dowels to a
length slightly less than the depth of the holes in the second piece.
(10) Trim off the sharp arrises. Fig. 156. (11) Glue the holes and the
edge of the second board. (12) Put the two members in the clamps and
set away until the glue has had time to harden.
[Illustration: FIG. 157.]
=87. Keyed Tenon-and-Mortise.=--Fig. 157 shows the tenon, the mortise
in the second member into which the tenon fits, the mortise in the
tenon and its key or wedge.
[Illustration: FIG. 158.]
=88. Directions for Key=:--Keys are made in quite a variety of shapes.
Some of the simple forms are shown in Fig. 158. Where two or more
keys of the same size are to be made, it is customary to plane all
in one piece. (1) Plane a face side, a face edge, gage and plane to
thickness. If there is more than one key, saw each to length. (2) Shape
the remaining edge as desired. The lines AB and CD, Fig. 158, indicate
the points at which measurements are to be made to determine the length
of mortise in the tenon which is to receive the key. These lines should
be laid off at a distance apart equal to the thickness of the tenon.
=89. Directions for Tenon.=--(1) Measure from the end of the piece the
length of the tenon, and mark with a knife point. Where tenons are to
be cut on both ends of a piece, measurement is frequently made from
the middle of the piece each way to locate the shoulders. Should there
be any variation in the length of the piece from what it should be,
this difference will then be equally divided at the ends. This is done
when it is more important to have the distance between the shoulders
of a definite length than that the tenons be of correct length. (2)
Square knife lines entirely around the piece at the knife point mark.
(3) Set the gage equal to the distance required from the face edge to
the nearest edge of the tenon and mark on both sides, as far as the
shoulder marks, and on the end. (4) Repeat, setting the gage from the
face edge to the farther edge of the tenon. If the two members are of
the same width and the tenon and mortise are to be equally distant
from the face edge, both tenon and mortise should be gaged with the
same settings. Frequently, the gage settings are obtained from the
rule indirectly. The rule is laid across the piece and the width or
thickness of mortise or tenon marked with the point of a knife blade,
Fig. 159. The spur of the gage is then set in one of these points,
the block being pushed firmly against the face; the thumb-screw is
then fastened, Fig. 160. The second setting is obtained in a similar
manner from the same edge or side. All the pieces are marked for the
first width before resetting. (5) After having laid out the mortise in
the tenon, rip to the gage lines and cross-cut to the shoulder lines,
paring if necessary. (6) Slightly bevel the ends of the tenon.
[Illustration: FIG. 159.]
[Illustration: FIG. 160.]
=90. Directions for Mortise.=--(1) From one end of the piece measure
and mark with the knife point the respective distances to the two
edges of the mortise. (2) Square lines across the face edge and the two
broad surfaces at these points. (3) Set the gage equal to the required
distance from the face edge to the nearer edge of the mortise and mark
between the lines. (4) Set the gage equal to the required distance from
the face edge to the farther edge of the mortise and mark between the
lines. Make both gage lines on face side and side opposite as well.
(5) Cut the mortises. First, bore a series of holes thru the mortise,
using a bit somewhat smaller than the width of the mortise. Bore these
holes so that they connect one with another. (6) Place the piece on a
chiseling board and, taking thin cuts about half way thru, work from
the middle of the mortise out to within one thirty-second of an inch
of the knife and gage lines. (7) Reverse and chisel from the other
side, finishing it; then chisel the first side out to the lines. Test
the sides of the mortise with a straight edge--the blade of the chisel
makes a good one--to see that they are cut straight. Fig. 161.
[Illustration: FIG. 161.]
=91. Directions for Mortise in the Tenon.=--(1) Lay out the sides of
the mortise for the key before the sides and shoulders of the tenons
are cut. From the shoulder line of the tenon, measure toward the end a
distance slightly less--about one thirty-second of an inch--than the
thickness of the member thru which the tenon is to pass. This is to
insure the key’s wedging against the second member. (2) Square this
line across the face edge and on to the side opposite the face side.
(3) On the top surface measure from the line just squared around the
piece a distance equal to the width the key is to have at this point
when in place. Fig. 158, A B. (4) Square a pencil line across the
surface at this point. (5) In a similar manner, measure and locate a
line on the opposite side, C D, Fig. 158. (6) Set the gage and mark
the side of the mortise nearer the face edge on face side and side
opposite. (7) Reset, and from the face edge gage the farther side of
the mortise, marking both sides. (8) This mortise may be bored and
chiseled like the one preceding. As one side of the mortise is to be
cut sloping, a little more care will be needed.
[Illustration: FIG. 162.]
=92. Blind Mortise-and-Tenon.=--Probably no joint has a greater variety
of applications than the blind mortise-and-tenon, Fig. 162. It is of
equal importance to carpentry, joinery and cabinet-making. The tenon
shown has four shoulders; it is often made with but three or two.
=93. Directions for Tenon.=--(1) Measure from the end of the piece the
length of tenon, (see also directions for tenon, Section 89) and mark
with the point of a knife. (2) Square knife lines entirely around the
four sides at this point to locate the shoulders. (3) Lay the rule
across the face edge near the end of the piece and mark points with
the end of the knife to indicate the thickness of the tenon, Fig. 159.
(4) With the head of the gage against the face side, set the spur of
the gage in one of these marks, then fasten the set screw, Fig. 160.
Gage on the end and the two edges as far back as the knife lines. When
there are several tenons remember to mark all of them before resetting.
(5) Set the gage in the other mark, the head of the gage being placed
against the face side; then gage as before. (6) In a similar manner,
place the rule across the face side, mark points with the knife for
the width of tenon, set the gage to these points, and gage on the face
and side opposite as far as the shoulder lines and across the end. The
head of the gage must be held against the face edge for both settings.
(7) Rip to all of the gage lines first, then crosscut to the shoulder
lines, using back-saw. (8) The end of the tenon may be slightly beveled
that it may be started into the mortise without tearing off the arrises
of the opening.
=94. Directions for Laying out Mortise.=--(1) From one end of the piece
measure the required distance to the nearer and the farther ends of the
mortise. Mark points with the knife. (2) Square lines across at these
points. (3) Lay the rule across the face into which the mortise is to
be cut and mark points with the knife for the sides of the mortise. (4)
Set the gage as was done for the tenon, the spur being placed in the
knife point mark and the head of the gage being pushed up against the
face. Gage between the cross lines. (5) Reset from the same face for
the other side of the mortise, and then gage.
If a mortise or tenon is to be placed in the middle of a piece, find
the middle of the piece, Fig. 3, Chapter I, Section 1, and with the
knife, place points to each side of the center mark at a distance
equal to one half the thickness or width of the tenon or mortise. When
several mortises or tenons of the same size are to be laid out and are
to be equally distant from a face, the gage needs to be set but twice
for all--once to mark the nearer edges and once for the farther edges
of the tenon or mortise. Should there be several like members with like
joints, the gage settings obtained from the first piece will suffice
for all.
The importance of working from face sides or face edges only, cannot
be overestimated. To work from either of the other two sides of a
piece would make the joints subject to any variation in the widths
or thicknesses of the pieces. To gage from the faces only, insures
mortises and tenons of exact size no matter how much the pieces may
vary in widths or thicknesses.
=95. Directions for Cutting Mortise.=--Two methods of cutting mortises
are in common use, (a) boring and chiseling, and (b) chiseling alone.
_First method_: (1) Fasten the piece in the vise in a horizontal
position. (2) Bore a series of connecting holes to the required depth,
Chapter IV, Section 45, with a bit slightly smaller than the width of
the mortise. (3) The sides of the mortise are next pared to the gage
and knife lines, beginning at the auger holes and working with thin
slices toward the lines. This method requires care and patience in
order to get the sides of the mortise cut square to the surface. It is
especially well adapted to large mortises from which much wood is to be
removed.
[Illustration: FIG. 163.]
[Illustration: FIG. 164.]
=96. Directions for Cutting Mortise.=--_Second Method_: (1) Clamp the
piece which is to be mortised firmly to the bench top, using a hand
clamp. Fig. 163 shows a little device called a mortise grip. Tighten
the vise screw and tap the grip with the mallet until it holds the
piece solidly. (2) Select a chisel of a width equal to that desired
for the mortise. Stand well back of the mortise at one end or the other
so as to be able to sight the chisel plumb with reference to the sides
of the mortise. (3) Begin the cutting in the center of the mortise.
Make the first cut with the bevel of the chisel toward you; reverse the
bevel and cut out the wedge-shaped piece, w, Fig. 164. (4) Continue
cutting in this manner until the proper depth has been attained, making
the opening no larger at the surface than is necessary. (5) Set the
chisel in a vertical position, bevel towards you, begin at the center
and, taking thin slices, cut toward the farther end. Drive the chisel
the full depth of the mortise each time, then pull the handle towards
you to break the chip from the sides of the mortise. Cut to within
one-eighth of an inch of the end of the mortise. (6) Reverse the piece,
or your position, and cut in a similar manner to within one-eighth of
an inch of the second end. (7) With the bevel side of the chisel next
the end of the mortise pry out the chips once or twice as the cutting
proceeds. (8) Chisel the ends to the knife lines, carefully sighting
the chisel for the two directions. Fig. 165 suggests the order.
[Illustration: FIG. 165.]
=97. Miter Joint.=--The miter joint is subject to various
modifications. In the plain miter, Fig. 166, the ends or edges abut.
They are usually fastened with glue or nails or both. The most common
form of the plain miter is that in which the slope is at an angle of
forty-five degrees to the edge or side.
[Illustration: FIG. 166.]
[Illustration: FIG. 167.]
=98. Directions for Miter Joint.=--(1) Lay off the slopes (see Chapter
I, Section 4). (2) Cut and fit the parts. To fit and fasten four
miter joints, such as are found in a picture frame, is no easy task.
Special miter boxes are made for this purpose which make such work
comparatively easy. (3) Fig. 167 shows the manner of applying the hand
clamps to a simple miter joint. When a joint is to be nailed, drive
the nail thru one piece until its point projects slightly. Place the
second piece in the vise to hold it firmly. Hold the first piece so
that its end projects somewhat over and beyond that of the second; the
nailing will tend to bring it to its proper position, Fig. 168. If a
nail is driven thru from the other direction, care must be taken to so
place it that it will not strike the first, or a split join will result.
[Illustration: FIG. 168.]
=99. Dovetail Joint.=--Dovetailed joints are so named from the shape
of the pieces which make the joint. Fig. 169 shows a thru multiple
dovetail commonly used in fastening the corners of tool boxes. In hand
made dovetails, the tenons are very narrow and the mortises wide, while
in machine made dovetails, tenons and mortises are of equal width.
Mechanics lay out the tenons without measurement, depending upon the
eye unaided to give the proper size and shape. Sometimes dovetails are
laid out to exact shape and size, the tenons being marked on both sides
and ends. The mortises are marked with trysquare and bevel after one
side of each has been marked by superimposing the tenons. In some kinds
of dovetailing, such as the half-blind dovetail, the mortises are made
first and the tenons marked out from them by superposition.
[Illustration: FIG. 169.]
[Illustration: FIG. 170.]
=100. Directions for Dovetail Joint.=--(1) Square lines around each
end to locate the inner ends of the mortises and tenons. These lines
will be at a distance from the ends equal to the respective thicknesses
of the pieces. (2) Determine the number of tenons wanted and square
center lines across the end of the member which is to have the tenons.
Place these center lines so that the intervening spaces shall be equal.
(3) Measure along an arris and mark on either side of these center
lines one-half of the desired width of the tenon. In fine hand made
dovetails, the usual width for the narrow edge of tenon is scarcely
more than one-sixteenth of an inch--the width of a narrow saw kerf.
(4) Set the bevel for the amount of flare desired. Fig. 170 shows
measurements which may be used in setting the bevel. A flare stick may
be made of thin wood and used instead of a bevel if desired, Fig. 170.
(5) Mark the flares on either side of the center lines. Place the bevel
so that the wide side of the tenon shall be formed on the face side of
the piece. (6) Carry these lines back on each side of the piece as far
as the lines previously drawn across these sides. (7) With a fine tenon
saw rip accurately to the lines. Cut the kerfs out of the mortises,
not out of the tenons. (8) Chisel out the mortises formed between the
tenons and trim up any irregularities in the tenons. (9) Set the
tenons on end on the face side of the second member, with the face side
just touching the cross line placed on the second member, Fig. 171, and
mark along the sides of the tenons. (10) Square lines across the end to
correspond with the lines just drawn. (11) Saw accurately to the lines,
cutting the kerfs out of the mortises, not the tails. Chisel out the
mortises for the tenons, Fig. 172. (12) Fit the parts together.
[Illustration: FIG. 171.]
[Illustration: FIG. 172.]
CHAPTER IX.
ELEMENTARY CABINET WORK.
=101. Combination Plane.=--The most elementary of cabinet work
necessitates considerable groove cutting, rabbeting, etc. Rabbets and
grooves can be formed by means of the chisel, the sides first being
gaged. A better way, by far, is to plane them. In earlier practice,
joiners were obliged to have a great variety of special planes--one for
each kind of work, and frequently different planes for different sizes
of the same kind of work. There were rabbeting, dado, plow, filletster,
beading, matching planes, etc., etc.
[Illustration: FIG. 173.]
Fig. 173 illustrates a modern combination plane which, by an exchange
of cutters, can be made to do the work of a (1) beader, center beader,
(2) rabbet and filletster, (3) dado, (4) plow, (5) matching plane,
and (6) slitting plane, different sized cutters for each kind of work
permitting of a great variety of uses. By means of a guide or fence,
the plane can be set to cut to a required distance from the edge of the
board. A stop or depth gage can be set so as to keep the plane from
cutting any deeper than is desired. When cutting across the grain, as
in cutting dadoes, adjustable cutting spurs precede and score or cut
the fibers of the wood on either side of the cutter.
=102. Drawer Construction.=--The front of a drawer is usually made of
thicker stock than the other parts. Fig. 174. For example, if the front
were to be made of three-quarter inch stock the sides, back and bottom
would probably be made of three-eighths inch material. Drawer fronts
are always made of the same material as the rest of the cabinet or desk
while the sides, back and bottom are usually made of some soft wood
such as yellow poplar.
[Illustration: FIG. 174.]
[Illustration: FIG. 175.]
Fig. 175 A illustrates a very common method of fastening the drawer
sides to the front. This form is used mainly upon cheap or rough
construction. It is commonly known as a rabbeted joint. The half-blind
dovetail, Fig. 175 B, is a better fastening, by far, and is used almost
exclusively on fine drawer construction.
=103. Directions for Rabbeted Corner.=--The rabbeted joint, Fig. 175 A,
sometimes called a rebate or ledge joint is made as follows: (1) Line
across the face side of the drawer front at a distance from the end
equal to the thickness of the drawer sides; also, across the edges to
the approximate depth of rabbet. (2) Set the gage and gage on ends and
edges as far as the lines just placed, for the depth of rabbet. (3) Cut
the sides of rabbet, paring across the grain as in cutting the dado.
Fasten by nailing thru the drawer sides into the front, not thru the
front into the sides.
=104. Directions for Dovetail Corner.=--The front of the drawer should
be laid out and cut first. (1) Gage on the end the distance the drawer
side is to lap over the front. (2) Without changing the setting of the
gage, hold the head of the gage against the end of the drawer side and
gage on both broad surfaces. Ordinarily, one should not gage across
the grain of the wood nor should the head of the gage be held against
other than a face. A little thought will show why exception has been
made in this case. (3) Square a line across the face side--the inside
surface--of the drawer front at a distance from the end equal to the
thickness of the drawer side. This line gives the depth of mortise for
the tails. (4) The groove for the drawer bottom having been cut, or
its position marked on the end of the front, lay out on the end the
half tenons at both edges so that the groove shall come wholly within
a tail mortise. The amount of flare at which to set the bevel is given
in Chapter VIII, Section 100. (5) Determine the number of tenons wanted
and divide the space between the flares just drawn into the required
number of equal parts and draw center lines for the tenons, Fig. 176.
(6) With the bevel lay off to either side of these center lines the
sides of the tenons. (7) Carry these lines down the face side to meet
the line previously drawn to indicate mortise depth. (8) Saw exactly to
the knife lines, cutting, Fig. 177, the kerfs out of the mortises, not
the tenons. (9) Chisel out the mortises. Fig. 178.
[Illustration: FIG. 176.]
[Illustration: FIG. 177.]
[Illustration: FIG. 178.]
[Illustration: FIG. 179.]
The corresponding mortises and tails may now be laid out on the drawer
side and worked. (10) By superposition, Fig. 179, mark out the shape
of the mortises to be cut in the sides. (11) Saw and chisel these
mortises. Fig. 172.
=105. Directions for Drawer.=--(1) Square the different members to
size. (2) Groove the front and sides of the drawer to receive the
drawer bottom. These grooves should be made somewhat narrower than the
bottom is thick to insure a good fit. The under side of the bottom,
later, may be gaged and beveled on the two ends and the front edge,
Fig. 180. (3) Lay out and cut in the drawer sides the dadoes into which
the ends of the back are to be fitted, Fig. 181. (4) Lay out and cut
the joints on the front of the drawer. (5) Get the bottom ready; that
is, plane the bevels on the under side as suggested in 2, above. (6)
Assemble the members dry to see that all fit properly. (7) Take apart;
glue the joints by which the sides are fastened to the front and the
joints by which the back is fastened to the sides. Glue the bottom to
the front of the drawer but not to the sides or back.
[Illustration: FIG. 180.]
[Illustration: FIG. 181.]
Sometimes on large or rough work nails are used instead of glue to
fasten the members together. In this case the front, sides and back are
put together, the back being kept just above the grooves in the sides.
The bottom is then slipped in place under the back. It is fastened to
the front of the drawer only. Especial care should be taken in squaring
the bottom for the squareness of the drawer is dependent upon this.
=106. Paneling.=--Often it is desired to fill in a rather wide space
with wood. To offset the effects of shrinkage, winding and warpage,
a panel rather than a single solid piece is used. By increasing the
number of panels a space of any size may be filled. Fig. 182.
[Illustration: FIG. 182.]
=107. Cutting Grooves.=--Grooves for panels are best cut by means of
the panel plow or combination plane. It is not necessary to gage for
the sides of the groove; the adjustments of the plane are such as to
give the proper depth and location, when once set, and a cutter of the
width equal to that of the desired groove inserted. The fence of the
plane must be held against one or the other of the faces. Fig. 173.
=108. Haunched Mortise-and-Tenon.=--A groove must be plowed the full
length of a piece to work it to advantage. Where a mortise-and-tenon
joint is to be made in which the grooved surface is to become a part,
the tenon must be so cut as to allow its filling the groove. The
mortise should be cut before the groove is plowed. The tenon, after
being worked the full width, is gaged from the face edge to a width
equal to the length of the mortise and worked to that size. Fig. 183.
[Illustration: FIG. 183.]
Especial care must be taken in gluing up the frame that no glue shall
get into the grooves or on the edges of the panel.
=109. Rabbeting.=--Fig. 184 shows a corner of a frame rabbeted to
receive a glass. Rabbets are best worked with either a rabbet plane or
the combination plane. In rabbeting across the grain the spur must be
set parallel with the edges of the cutter.
[Illustration: FIG. 184.]
[Illustration: FIG. 185.]
Since the parts of the frame are rabbeted the full length for
convenience, a special joint is necessary at the corners. The mortises
are cut before the rabbets are worked. The tenons are laid out so that
the shoulder on one side shall extend as far beyond the shoulder on the
opposite side as the rabbet is deep. Fig. 185.
Where rabbeting must be worked with a chisel alone, Fig. 186
illustrates the manner of loosening up the wood preparatory to removing
it, when the rabbet extends along the grain of the wood.
[Illustration: FIG. 186.]
To place glass panels in rabbets, first place a slight cushion of putty
in the rabbet that the glass may rest against it. A light cushion
between the glass and the fillet will serve to keep the glass from
breaking and will keep it from rattling. Fig. 187.
[Illustration: FIG. 187.]
=110. Fitting a Door.=--A door is a frame with a panel or a combination
of panels. The names of the parts of a door and their relative
positions are indicated in Fig. 188.
[Illustration: FIG. 188.]
[Illustration: FIG. 189.]
(1) Mark with a trysquare and saw off the lugs, the parts of the stiles
which project beyond the rails. (2) Plane an edge of the door until it
fits a side of the frame against which it is to be hung. If the frame
is straight, this edge may be planed straight. It is not wise to take
for granted the squareness or straightness of a frame. A test or series
of tests may first be made with square and straight-edge. A mechanic,
however, usually planes an edge until it fits the frame, testing by
holding the door against the frame as near to its position as its
size will allow. (3) Plane the bottom or top edge of the door until
it fits the frame properly when the first planed edge is in position.
(4) Measure the width of the frame at its top and bottom, Fig. 189,
and transfer these dimensions to the top and bottom of the door,
connecting them with a straight edge. When approaching the line, in
planing, place the door against the frame often enough to see where the
allowances must be made for irregularities in the frame. (5) The length
of the frame may next be measured on each side and these dimensions
transferred to the door. Connect them with a straight edge and plane
and fit as was directed in the third step.
A door to work well must not be fitted perfectly tight; it must have a
little “play,” the amount depending upon the size of the door.
The edge of the door which is to swing free is usually planed slightly
lower at the back arris than at the front. An examination of the
movement of an ordinary house door will show the reason for this.
=111. Hinging a Door.=--The hinges most commonly used in cabinet making
and carpentry are the kind known as butts. Where the door stands in a
vertical position, hinges in which the two parts are joined by a loose
pin are generally used. By removing the pins the door may be removed
without taking the screws out of the hinge. Such hinges are more easily
applied than those with the fixed pin.
[Illustration: FIG. 190.]
[Illustration: FIG. 191.]
(1) Place the door in position; keep it tight against the top and the
hinge side of the frame. (2) Measure from top and bottom of the door to
locate the position for the top of the higher hinge and the bottom of
the lower hinge. Usually, the lower hinge is placed somewhat farther
from the bottom than the higher hinge is from the top. (3) With the
knife or chisel mark on both door and frame at the points just located,
Fig. 190. (4) Take out the door, place the hinge as in Fig. 191, and
mark along the ends, with a knife. In a similar manner mark the frame.
Make certain that the openings on door and on frame are laid off so as
to correspond before proceeding further. (6) Set the gage for the depth
the hinge is to be sunk and gage both door and frame. (7) Set another
gage for width of openings and gage both door and frame, keeping the
head of the gage against the front of the door. (8) Chisel out these
gains on door and frame. (9) If loose-pin butts are used, separate the
parts and fasten them in place. Use a brad awl to make openings for the
screws. To insure the hinges’ pulling tight against the side of the
gain make the holes just a little nearer the back side of the screw
hole of the hinge. Put the door in place and insert the pins. It is a
good mechanic who can make a door hang properly the first time it is
put up. It is better, therefore, to insert but one or two screws in
each part of a hinge until the door has been tried. (10) If the door
hangs away from the frame on the hinge side, take it off; take off
hinge on door or frame, or both if the crack is large; chisel the gain
deeper at its front. By chiseling at the front only and feathering
the cut towards the back, the gain needs to be cut but about one-half
as deep as if the whole hinge were sunk. If the door should fail to
shut because the hinge edge strikes the frame too soon, the screws of
the offending hinge must be loosened and a piece of heavy paper or
cardboard inserted along the entire edge of the gain. Fasten the screws
and cut off the surplus paper with a knife. If plain butt hinges are
used the operations are similar to those just described except that the
whole hinge must be fastened to the door and the door held in place
while fastening the hinges to the frame.
=112. Locks.=--Locks which are fastened upon the surface of a door are
called rim locks. Those which are set into mortises cut in the edge of
the door are called mortise locks. Locks are placed somewhat above the
middle of the door for convenience as well as appearance. Three styles
of cabinet locks such as are used on drawers and small boxes are shown
in Fig. 192.
[Illustration: FIG. 192.]
The manner of applying a cabinet lock will be suggested by the lock
itself. On surface locks, (1) the lock is held against the inside of
the door or drawer and the position of the keyhole is marked. (2) This
hole is bored. (3) The lock is screwed in place, and (4) the escutcheon
fastened to the outer or front surface. If a face plate is used, the
door is closed, the position marked, after which the door is opened and
the plate is set. The face plate is mortised into the frame so that
its outer surface shall be slightly lower than that of the wood. With
a lock such as the box lock, Fig. 192, sufficient wood must be removed
from the mortise so that the bolt may act properly before the plate is
screwed fast.
PART III.
WOOD AND WOOD FINISHING.
CHAPTER X.
WOOD.
=113. Structure.=--For convenience, tree structure is usually studied
(1) in transverse or cross section, (2) radially, (3) tangentially.
[Illustration:
V.--Vessels or pores.
T.S.--Tangential Section.
C.S.--Transverse „ „
R.S.--Radial „ „
FIG. 193.]
A transverse section is obtained by cutting a log at right angles
to its length; a radial section by cutting it along the radius; a
tangential section by making a cut at right angles to a radius. Fig.
193.
[Illustration: FIG. 194.]
If we should cut transversely a young tree, a sprout, or branch of
an oak or similar tree, we should find it composed of three layers
of tissue (1) pith or medulla, (2) wood, (3) bark, Fig. 194. These
tissues, if magnified, would be found composed of little closed tubes
or cells. Fig. 195.
Examine the end of a log cut from a tree such as the oak; we shall
find that the center, which in the young tree was soft, has become
hard and dry, and that upon it are marked a series of concentric
rings--rings having a common center. These rings are known as annual
rings because one is added each year.
Usually, about three-quarters of the rings from the center outward will
be found to have a different color from the remaining ones. These inner
rings form what is called heartwood. The wood of the remaining rings
will be found softer and to contain a larger proportion of sap. This
part is called sapwood. Young trees are composed mainly of sapwood. As
the tree grows older more of it is changed to heartwood, the heartwood
becoming greater in proportion to the sapwood with age.
[Illustration: FIG. 195.]
Upon examining these rings each will be found to be made up of two
layers; one a light, soft, open, rapid growth formed in the spring, the
other, a dark, hard, close, slow growth formed in the summer.
[Illustration: FIG. 196.]
Frequently, the center of the annual rings is not in the center of the
log. Fig. 196. This is due to the action of the sun in attracting more
nourishment to one side than to the other.
Surrounding the sapwood is the bark. The inner part of the bark is
called bast and is of a stringy or fibrous nature. Bark is largely
dead matter formed from bast, Fig. 195. Its function is to protect the
living tissues.
Between the bast and the last ring of the woody tissue is a thin layer
called the cambium. This layer is the living and growing part of the
tree. Its cells multiply by division and form new wood cells on the
inside and new bast cells on the outside.
Heartwood is dead so far as any change in its cells is concerned. Its
purpose is merely to stiffen and support the weight of the tree.
Sapwood, on the other hand, has many active cells which assist in the
life processes of the tree, tho only in the outer layer of cells, the
cambium, does the actual growing or increasing process take place.
Again examining the end of the log, we shall find bright lines
radiating from the center. They are composed of the same substance as
the pith or medulla and are called pith or medullary rays. These rays
are present in all trees which grow by adding ring upon ring but in
some they are hardly visible. The purpose of these horizontal cells is
to bind the vertical cells together and to assist in distributing and
storing up plant food.
[Illustration: FIG. 197.]
Fig. 197 shows a log cut longitudinally or lengthwise. The lines we
call grain, it will be seen, are the edges of the annual rings, the
light streaks being an edge view of the spring layer and the dark
streaks an edge view of the summer or autumn wood.
[Illustration: FIG. 198.]
Knots are formed by the massing or knotting of the fibers of the tree
through the growth of a branch. Fig. 198 shows the manner in which the
fibers are turned. This packing of the fibers is what causes a knot to
be so much harder than the rest of the wood.
=114. Growth.=--Sap is the life blood of the tree. In the winter
when most of the trees are bare of leaves there is but very little
circulation of the sap. The coming of spring with its increase of heat
and light, causes the tree to begin to take on new life; that is,
the sap begins to circulate. This movement of sap causes the roots
to absorb from the soil certain elements such as hydrogen, oxygen,
nitrogen and carbon, also mineral salts in solution. The liquid thus
absorbed works its way upward, mainly by way of the sapwood and
medullary cells. Upon reaching the cambium layer, the nourishment which
it provides causes the cells to expand, divide and generate new cells.
It also causes the buds to take the form of leaves.
When the sap reaches the leaves a chemical change takes place. This
change takes place only in the presence of heat and light, and is
caused by the action of a substance called chlorophyll. The importance
of the work performed by chlorophyll cannot be overestimated. Nearly
all plant life depends upon it to change mineral substance into food.
Animals find food in plant life because of this change.
Assimilation is the process of taking up and breaking up, by
the leaves, of carbonic acid gas with which the cells containing
chlorophyll come in contact. Carbon, one of the elements, is retained,
but oxygen, the other element, is returned to the air. Carbon is
combined with the oxygen and hydrogen of the water, which came up from
the roots, to form new chemical compounds. Nitrogen and earthy parts,
which came with the water, are also present.
Chlorophyll gives to leaves and young bark their green color.
The roots of the trees are constantly drinking plant food in the
daytime of spring and early summer. From midsummer until the end of
summer the amount of moisture taken in is very small so that the flow
of sap almost ceases.
The leaves, however, are full of sap which, not being further thinned
by the upward flow, becomes thickened thru the addition of carbonic
acid gas and the loss of oxygen.
Toward the end of summer this thickened sap sinks to the under side of
the leaf and gradually flows out of the leaf and down thru the bast of
the branch and trunk, where another process of digestion takes place.
One part of this descending sap which has been partly digested in the
leaves and partly in the living tissues of root, trunk and branch,
spreads over the wood formed in the spring and forms the summer wood.
The second part is changed to bark. What is not used at once is stored
until needed.
The leaves upon losing their sap change color, wither and drop off. By
the end of autumn the downward flow of changed sap from the leaves is
completed and the tree has prepared itself for the coming winter.
It must be remembered that the foregoing changes are made gradually.
After the first movement of the sap in the early spring has nourished
the buds into leaves of a size sufficient to perform work, there begins
a downward movement of food materials--slight at first, to be sure, but
ever increasing in volume until the leaves are doing full duty. We may
say, therefore, that the upward movement of the sap thru the sapwood
and the downward flow of food materials thru the bast takes place at
the same time, their changes being of relative volumes rather than of
time.
=115. Respiration and Transpiration.=--Plants, like animals, breathe;
like animals they breathe in oxygen and breathe out carbonic acid gas.
Respiration which is but another name for breathing, goes on day and
night, but is far less active than assimilation, which takes place only
during the day. Consequently more carbonic acid gas is taken in than is
given out except at night when, to a slight extent, the reverse takes
place, small quantities of carbonic acid gas being given off and oxygen
taken in.
Very small openings in the bark called lenticles, furnish breathing
places. Oxygen is also taken in thru the leaves.
Transpiration is the evaporation of water from all parts of the tree
above ground, principally from the leaves.
The amount of water absorbed by the roots is greatly in excess of what
is needed. That fresh supplies of earthy matter may reach the leaves,
the excess of water must be got rid of. In trees with very thick bark,
transpiration takes place thru the lenticles in the bottom of the deep
cracks.
=116. Moisture.=--Water is present in all wood. It may be found (1) in
the cavities of the lifeless cells, fibers and vessels; (2) in the cell
walls; and (3) in the living cells of which it forms over ninety per
cent. Sapwood contains more water than heartwood.
Water-filled wood lacks the strength of wood from which the greater
part of the moisture has been expelled by evaporation.
=117. Shrinkage.=--Water in the cell walls--it makes no difference
whether the cells are filled or empty--causes their enlargement and
consequently an increase in the volume of the block or plank. The
removal of this water by evaporation causes the walls to shrink; the
plank becomes smaller and lighter. Thick walled cells shrink more than
thin ones and summer wood more than spring wood. Cell walls do not
shrink lengthwise and since the length of a cell is often a hundred
or more times as great as its diameter the small shrinkage in the
thickness of the cell walls at A and B, in Fig. 199, is not sufficient
to make any noticeable change in the length of the timber.
[Illustration: FIG. 199.]
[Illustration: FIG. 200.]
Since the cells of the pith or medullary rays extend at right angles
to the main body, Fig. 200, their smaller shrinkage along the radius
of the log opposes the shrinkage of the longitudinal fibers. This is
one reason why a log shrinks more circumferentially, that is along the
rings, than it does radially or along the radii. A second cause lies in
the fact that greatly shrinking bands of summer wood are interrupted,
along the radii, by as many bands of slower shrinking spring wood,
while they are continuous along the rings.
[Illustration: FIG. 201.]
This tendency of the log to shrink tangentially or along the radii
leads to permanent checks. Fig. 201 A. It causes logs sawed into boards
to take forms as shown in Fig. 201 B.
Warping is caused by uneven shrinkage. Sapwood, as a rule, shrinks more
than heartwood of the same weight. The wood of pine, spruce, cypress,
etc., shrinks less than the wood of trees such as the oak.
=118. Weight.=--Wood substance is 1.6 times as heavy as water; it
matters not whether it be wood of oak, pine or poplar. Wood placed in
water floats because of the air enclosed in its cells; when the cells
become filled with water it sinks.
The weight of any given piece of wood is determined (1) by the wood
substance--this is always the same; (2) by the amount of water enclosed
in its cells--this varies.
Some kinds of woods are heavier than others similarly seasoned because
they contain more wood substance in a given volume.
Weight of wood is an important quality. To a large extent, strength is
measured by weight; a heavy piece of oak will be stronger than a light
one of the same species.
Lightness, strength and stiffness are properties which recommend wood
for different uses.
=119. Other Properties.=--Strength, elasticity, hardness, toughness and
cleavability as applied to timber, have their usual meaning.
=120. Grain.=--Wood fibers generally extend parallel to the axis of the
trunk or branch which they form. In this case the wood is said to be
straight grained.
[Illustration: FIG. 202.]
[Illustration: FIG. 203.]
Frequently, the fibers grow around the tree as in Fig. 202, or several
layers may grow obliquely in one direction and the next series grow
obliquely in the opposite direction, Fig. 203. Boards cut from such
trees will be cross grained or twisted.
The surface of the wood under the bark is seldom smooth. Usually
these hollows are filled even by the addition of one or two new rings
of growth. However, in some woods as maple, the unevennesses are
maintained, the high places being added to as are the low. Fig. 204. A
board cut tangentially from the tree in which the depressions are small
and numerous will have “birds’ eyes”. Dormant buds frequently cause
small cone-shaped elevations, which tho covered with successive layers
of new wood, retain their shape. Cross sections of these cones will
appear on the sawed board as irregular circles with a dark speck in the
center.
[Illustration: FIG. 204.]
[Illustration: FIG. 205.
FELLING RED SPRUCE WITH THE SAW. ADIRONDACK MOUNTAINS, NEW YORK.]
CHAPTER XI.
LUMBERING AND MILLING.
=121. Lumbering.=--Lumbering is of two kinds: conservative and
ordinary. The first seeks to so treat the forest that successive
crops may be produced; the second takes no account of the future. It
cuts only the better parts of the trees, often destroying young and
promising trees in so doing.
Lumbering in the United States in usually carried on at quite a
distance from habitation. A camp is, therefore, prepared at a spot
convenient for the logging operators. Here the men eat and sleep.