and, holding it as already shown at Fig. 273, strike the gauge lines on
the wood as illustrated at Fig. 302, G. Proceed to mark out the dovetail
pins, as at Fig. 303; in this illustration G again shows the gauge line.
The inclination of the lines across the end of the wood should not be too
great, or the joint will be a weak one, and the edges of the dovetails
will be liable to crumble away when the work is knocked together.
DOVETAILING TEMPLATE.--Many workers who are constantly engaged upon
dovetail joints make a small wooden template, as shown at Fig. 304. This
template is generally of hardwood, such as beech or walnut. The method of
obtaining the correct angles of such a template has already been given on
p. 134. Notice that the lines _bb_ (Fig. 303) of the dovetail pins do
_not_ bevel; they are parallel to the sides of the wood and at right
angles to the end of the wood as shown.
[Illustration: Fig. 302.--Gauging.]
[Illustration: Fig. 303.--Marking the Pins.]
CHISEL WORK.--After marking out, as shown at Fig. 303, place the wood on
the bench and proceed to chop away the centre portion in the following
manner. Hold the chisel on the bevel and cut out a small piece to form a
channel at the gauge line. Now hold the chisel in a vertical position,
and with a mallet strike it so as to make a cut about 1/8 in. deep. Then
hold the chisel on the bevel again and cut away more waste wood; proceed
alternately, first forcing the chisel down vertically, and then paring
the wood away with the chisel held obliquely, until you have cut
half-way through the thickness of the wood.
[Illustration: Fig. 304.--Hand-made Template for Marking Dovetails.]
[Illustration: Fig. 305.--Testing.]
[Illustration: Fig. 306.--The Marked Piece.]
Turn the wood over and repeat the various operations until the core, or
waste piece, is removed. Pare away any little irregularities which may be
left in the corners with an 1/8-in. chisel, thus leaving all smooth and
neat. Lay the piece of wood which is to have the dovetail marked on it
flat upon the bench, and take the piece with the dovetail pins cut upon
it and place in the position shown at Fig. 305.
SAW WORK.--Take a marking awl, or a knitting needle which has had its end
sharpened, and mark the lines of the dovetail in a similar manner to that
shown at Fig. 307. Remove the piece A, Fig. 305, and the lower piece
shown at Fig. 305 will clearly show the marks _aa_ as they appear in Fig.
306. Place the piece (Fig. 306) in the vice, and saw _outside_ the lines
AA, as shown in Fig. 308.
[Illustration: Fig. 307.--Marking Dovetails with Marking Awl.]
After sawing down the lines AA, Fig. 308, place the wood in the vice and,
guiding the saw blade with the index finger of the left hand, cut away
the small piece at the side (see Fig. 275). Repeat the operation as may
be necessary, and the completed joint will be similar to that shown at
Fig. 300. If the sawing is not neatly done it may be found necessary to
pare the shoulder with a sharp chisel.
DRAWERS.--When dovetailing drawers or boxes it is necessary to square up
the ends of all the stock and gauge them, as shown at Fig. 273. This
illustration shows how to gauge the lines on a drawer side; the
dovetailed joint in this case, however, does not run through the drawer
front and leave the work unsightly, as the joint at Fig. 300 would do.
The method used is shown at Fig. 309, and it is commonly known as
lap-dovetailing. Most workers cut the dovetail pins on the drawer fronts
and the drawer backs first, after which they mark the drawer sides with
the marking awl. The dovetailing of the drawer back is shown at Fig. 310.
This is the type known as "through dovetailing," the method being similar
in regard to tool operations as the single joint shown at Fig. 300.
[Illustration: Fig. 308.--Sawing the Dovetails.]
[Illustration: Fig. 309.--Lap-dovetailing Drawer Front to Drawer Side.]
[Illustration: Fig. 310.--Through Dovetailing.]
[Illustration: Fig. 311.--Chipping Waste of Lap Dovetail.]
When the pins on the drawer front have been sawn, the waste material is
cut away, as at Fig. 311. First stab down with the vertical chisel,
which must make the cut about 1/32 in. in front of the gauge line (see
illustration). This commencing of the cut slightly in front of the gauge
line is a very important feature. The chisel may be likened to a wedge,
and if the chisel edge be placed exactly upon the gauge line and force
be applied to the handle, it will force the timber away equally on each
side of the gauge line, and the finished depth of the hole will therefore
be too deep for the thickness of the drawer side; in other words, it will
press itself over the gauge line on both sides.
By taking the first vertical cut on the waste side of the gauge line, and
then removing a small piece with the chisel held obliquely, as at Fig.
311, the wood is removed and less resistance is offered to the chisel
when the next vertical cut is made. This overshooting the gauge line is a
common fault with the beginner, who is puzzled at the result because he
is certain he had his chisel exactly on the gauge line when he commenced
his vertical cut. It is especially noticeable in soft-grained woods.
To cut away the waste of a lap-dovetail (Fig. 311), the vertical and
oblique cuts are repeated until the final trimming up is required, and
now is the time to finish both the vertical and the horizontal cuts
exactly on the gauge lines.
Some workers prefer to cut the drawer sides first, and if this method is
preferred (and it has its advantages for cheap work) several drawer sides
are cut at once by placing four or six behind one another in the vice and
sawing them all at one operation.
The drawer front is placed in the vice, and the drawer side held upon it,
whilst the saw blade is placed in the saw kerf and drawn smartly forward.
This will give the required marks at the exact position desired. It must
be remembered, however, to saw just inside these dovetail-pin lines,
otherwise the finished joint will be too slack, owing to the removal of
the sawdust, which is practically equal to the thickness of the saw
blade.
MACHINE-MADE DOVETAILS.--As a general rule machine-made drawer and box
dovetails show both the pins and the tails of exactly the same size. The
reason is obvious after an inspection of Fig. 314, which shows the
position in which the pieces are held during the machining operations. In
spite of a certain amount of prejudice they are satisfactory and
thoroughly reliable and have their place in modern shop and office
fittings.
[Illustration: Fig. 312.--Machine-made Drawer Front and Side, Apart.]
[Illustration: Fig. 313.--The Parts Together.]
[Illustration: Fig. 314.--Position when Machined.]
DOVETAIL GROOVING
The dovetail housing joint should first be carefully marked out with a
marking knife, so as to cut across the fibres of the wood. For obtaining
the bevel on the edge of the wood a joiner's bevel may be used, and the
angle should not be too acute. (See previous chapter.) Take a chisel and
pare away a small channel as at A, Fig. 315, to form a small shoulder to
guide the saw.
[Illustration: Fig. 315.--Paring away Channel for Dovetail Grooving.]
With a fine tenon or dovetail saw, cut the saw kerf as at Fig. 316. If
any difficulty is experienced in cutting the kerf true and square, you
may resort to the method shown at C, Fig. 315; a small temporary piece of
timber has been screwed on the top of the work to form a guide for the
saw.
[Illustration: Fig. 316.--Cutting the Saw Kerf.]
[Illustration: Fig. 317.--Old Woman's Tooth Plane.]
[Illustration: Fig. 318.--Guide Block for Bevelling.]
Fig. 315, B, shows the small channel formed by the chisel prior to the
sawing operation. The sawing of the bevelled side is worked in a similar
manner; but occasionally we find amateurs who adopt the method shown at
Fig. 318. A block of wood (H) is first made by boring a 1-1/4-in. hole
through its entire length, and afterwards making a saw cut at the desired
bevel. The object of this block, which is kept specially for the purpose,
is to form a guide for those who have not full control of the dovetail
saw; the back of the saw clears the hole, and the required bevel is
obtained. When a saw cut has been made at each side of the groove, the
surplus timber is pared away in the following manner: Cut away portion E,
Fig. 319; then cut away portion F, and lastly cut away the apex portion
marked G. Continue by this method of paring until the approximate depth
is reached. To ensure a correct depth throughout the entire groove, the
router plane (or, as it is often called, "the old woman's tooth plane,"
Fig. 317) is used.
[Illustration: Fig. 319.--Showing Method of Paring.]
[Illustration: Fig. 320.--Channelling the Alternate Piece.]
With regard to cutting the alternate piece, it is necessary to first
plane the end of the shelf true and square. With a cutting gauge strike
the line K, Fig. 320; the required bevel on the edge (J) is then set out,
and with the chisel a small channel is again formed. With the tenon or
dovetail saw cut down the line K to the required depth, and carefully
pare away the wood with a sharp chisel to the correct shape.
THE MITRED JOINT
Although mitreing is used in everyday woodwork, it comes last in our list
of regular joints simply because it has been partly dealt with in almost
every previous chapter. For example, we have mitre halving in Fig. 34, a
mitre bridle joint in Fig. 74, a tongued and grooved mitre in Fig. 116,
mitred mortise and tenon joints in Figs. 148 and 159, a dowelled mitre
frame in Fig. 202, and a mitred dovetail in Fig. 286.
[Illustration: Fig. 321.--Mitred Skirting.]
[Illustration: Fig. 322.--Curved Mitre.]
[Illustration: Fig. 323.--Halving the Angle.]
MITREING.--The term mitreing is generally used to denote the type of
joint used at the corner of a picture frame; or where two pieces of wood
are bevelled away so as to fit each other, as the skirting or plinth
mould at Fig. 321. In these cases the timber is cut so that the joint is
at 45 degrees to the face, and the two pieces, when placed together,
form an angle of 90 degrees (a right angle).
The term mitreing, however, is not confined to the fitting of timber
around a right angle; it may be justly applied to the fitting of a
moulding around an angle irrespective of the number of its degrees.
One often hears such terms as "a half mitre," used to denote the fitting
of a moulding around an octagonal column or pedestal, and probably it
would be more correct to describe the joint as a mitre cut at 22-1/2
degrees. Mitreing consists of halving the angle and making each piece to
fit the line of bisection. Should the angle be bounded by straight lines,
as at Fig. 321, then the mitred joint will be a straight line, but should
the angle be bounded by a curved and a straight line, as at Fig. 322, A,
or by two curved lines, then the mitred joint will have to be a curved
line if the mouldings are to be of the same section.
[Illustration: Fig. 324.--Sawing Block for Mitreing.]
FINDING THE ANGLE.--For straight mitres, the mitre joint line is found by
bisecting the angle, as shown in the various examples, and the following
instructions are given to enable the reader to follow the diagram (Fig.
323). Take a pair of compasses, or dividers, and with any convenient
opening strike out the arc A, B. Put the point of the compasses on A, and
mark another arc C; then, without altering the distance between the
points of the compass, put the point on B, and mark the arc D. Draw the
line E from the corner, so that it cuts through the intersection made by
the arcs C and D. The angle A B is now halved by the line E, and this
method may be applied to any angle.
SAWING BLOCK.--For sawing mouldings, etc., to their approximate shape, a
home-made sawing block is generally used, as shown at Fig. 324. Two
pieces of wood are glued one on the top of the other, the required angle
is transferred thereto, and the saw kerf made. In the sketch the saw
kerfs are shown at 45 degrees, right and left, and other angles and kerfs
may be made where desired.
PLANING.--After sawing the piece to approximately the correct angle, it
is necessary on high-class work to plane the cut end so as to give a
perfect finish and enable a glued joint to be made. This may be
accomplished by using the plane on the shooting board, as shown at Fig.
325, and, if the worker is constantly using mitres of various angles, it
is an easy matter to make new angle blocks and fix them on to the board.
Other workers prefer the screw mitre trap shown at Fig. 326. This
apparatus takes wide plinth or cornice moulds, and the angle may be
altered by fitting temporary packing pieces under the work so as to tilt
the moulding to the desired angle. The method of using the plane is
indicated in the illustration.
Another method in everyday use by those workers who are constantly
mitreing wide pieces of stock at 45 degrees is the "donkey's ear"
shooting board illustrated at Fig. 327. The plane is laid on its side on
the surface of the board marked A, and used in a similar manner to that
shown at Fig. 325.
[Illustration: Fig. 325.--Use of Plane and Shooting Board for Mitreing.]
[Illustration: Fig. 326.--The Screw Mitre Trap.]
A simple method and one that should always be remembered because it is
handy when working without a shooting board is shown at Fig. 328. Set the
marking or cutting gauge to the thickness of the wood to be mitred at 45
degrees; then gauge this distance on the wood, as shown at B; draw from
the line to the edge, as shown, and saw and plane to a finish. The
diagonals of a square give 45 degrees, and this is the method used to
mark out the work. The end of the wood must, of course, be square with
its edges before marking out in this manner.
[Illustration: Fig. 327.--"Donkey's Ear" Shooting Board.]
[Illustration: Fig. 328.--Gauging for Mitres.]
[Illustration: Fig. 329.--Narrow Inner Moulding.]
[Illustration: Fig. 330.--Wide Mitred Moulding.]
Fig. 329 shows a bevelled framing into which has been mitred a narrow
moulding M so as to show a correct margin around the panel.
[Illustration: Fig. 331.--Door with Curved Mitres.]
[Illustration: Fig. 332.--Method of Setting out for a Curved Mitre.]
Fig. 330 shows a similar framing, but with a wide moulding M mitred
around it. To obtain a correct intersection of this moulding, the angles
A and B are bisected. The bisection of the angles meets before the width
of the moulding is cleared, therefore the angle C will again have to be
bisected, and the finished joint will appear as shown. One of the
simplest of mouldings with a large flat face has been chosen to
illustrate this. The moulding could be all in one width, as shown, or it
could be built into the framing in separate pieces, the wide flat and the
piece carrying the mould.
CURVED MITRES.--We now come to what are probably the most difficult of
all mitres, viz., curved mitres, and the writer well remembers in his
apprenticeship days his first experience of attempting to fit the
mouldings around the door shown at Fig. 331 by using straight mitres at
A. This, of course, is impossible if the mouldings are of the same
section and it is desired to make all the members correctly intersect. If
straight mitres are used the section of the curved moulding will have to
be of a different shape from the section of the straight moulding, and in
these days of machine-made mouldings this method is seldom resorted to.
It is better, cheaper, and easier to make curved mitres when the
necessary machinery is at hand.
TO SET OUT A CURVED MITRE (see Fig. 332).--Draw a section of the moulding
full size, A, as shown at the left hand of the illustration, and project
lines round the framing, as shown V, W, X, Y and Z. Where the lines V, W,
X, Y and Z intersect at the corner D, it clearly shows that a straight
mitre will not cut all the points of intersection. A curved line will cut
all the intersections, and a template made of cardboard, sheet zinc, or
veneer, should be made to this shape. At the left-hand side the
geometrical setting out is shown for obtaining the curve without having
to resort to drawing it freehand.
Take half the width of the moulding, as shown by dotted line A, and where
it cuts the approximation of the curved mitre place the point of the
compasses and strike out a circle as shown; with the same radius place
the compass point on B--that is, the inside point of the mitre, and cut
the circle on the right and left with the small arcs shown at _aa_. With
the same radius put the compass point at the junction of the circle and
mitre line, C V, and cut the circle at right and left, viz., _ee_.
[Illustration: Fig. 333.--Template for Mitreing.]
Now rule a line through _aa_, and another line through _ee_, and where
these lines cut each other it will give the correct radius of the curved
mitre. The advantage of knowing the correct radius of a curved mitre is
of great benefit to the skilled machinist, as it enables him to set up
his machine so as to give a definite result.
MITREING A MOULDED DOOR FRAME.--Fig. 333 illustrates the method of
mitreing the moulded portion of a door frame where the joint is dowelled,
not tenoned. A small wooden template is made out of beech or other
hardwood, having its ends cut at 45 degrees. This template is placed on
the rail, as shown, and held in position by placing both the rail and the
template in the vice. The face of the template forms a guide for a wide
chisel, and enables the worker to gradually pare away the moulding to the
correct angle.
[Illustration: Fig. 334.--Using Panel Saw in Mitre Box.]
For sawing the mitres on large mouldings such as are used on the lid of a
gramophone or wireless cabinet, a mitre sawing box and a panel saw may be
used as indicated at Fig. 334.
JOINTS FOR CURVED WORK
Fig. 335 shows a circular frame made up in two thicknesses, the segments
being screwed to each other and the joints crossed in two layers. This is
a very strong method, and it is used for making circular frames and curbs
up to 15 ft. in diameter. The segments can be either long or short, the
only important condition being that they must be marked out and sawn to
the correct radius. Fig. 337 shows a board marked out in segments for
this class of work. The longer the boards the better will they cut up, as
it gives more opportunities of cutting one piece out of the other as at A
A.
[Illustration: Fig. 335.--Circular Frame in Two Thicknesses.]
[Illustration: Fig. 336.--Circular Rim in Halved Segments.]
Fig. 338 shows how to begin to put the work together. To continue this,
fit other segments in position and screw them to D and E respectively.
The completed work is illustrated at Fig. 335.
[Illustration: Fig. 337.--Board Marked for Circular Jointing.]
[Illustration: Fig. 338.--Putting Circular Work Together.]
[Illustration: Fig. 339., Fig. 340. Method of Building up
Semicircular Head of Door Frame.]
Fig. 336 shows a circular rim, or curb, made of segments which are halved
together. This method is suitable for heavy work, where the timbers are
of considerable size. The halvings are cut on the ends of the segments
to any convenient shape or bevel, each one being marked so as to fit its
fellow.
[Illustration: Fig. 341.--Part of Laminated Table Frame.]
[Illustration: Fig. 342.--Half of Laminated Core Box.]
When extra length is required, semicircular or circular work is built up
out of four or five thicknesses of wood, and the method is called
laminating. The method of building up the semicircular head of a door
frame by this method is shown at Figs. 339 and 340.
The shaped framing for kidney-shaped writing tables and similar classes
of work is built up by laminating pieces of 3/4-in. or 1-in. wood, after
which the face side is veneered so as to hide the glued joints. Fig. 341
shows a sketch of one quarter of an elliptical table frame levelled up
and ready for applying the veneer.
LAMINATION.--If we apply to the dictionary for the word "lamination," we
find that lamellar structure is the arrangements in thin plates or layers
one over the other, usually having the end joints alternating, and it is
a condition which allows of cleavage in one direction only. This method
is used for nearly all descriptions of free or irregular curves, such as
sweeps, bends, ogee shapes, and segments of circles. The timber is marked
out in suitable lengths, rough-sawn and then planed true on the face,
glued together, and when set the sides are cleaned up to the required
shape. It is one of the strongest methods of construction, and
necessarily costly. Pulleys, pulley rims, and a hundred and one other
jobs are built by this method.
Fig. 342 shows one half of a core box built by this method, ready to be
worked to the required shape.
MISCELLANEOUS JOINTS
Weather boards.--For outdoor buildings, such as garages, garden sheds,
toolhouses, etc., "weatherboarding" is often preferred to ordinary
matchboarding, chiefly because of the facility with which it throws off
the rain. The boarding can be bought ready prepared. Three methods of
jointing are shown in the sections at Fig. 343. The method indicated at A
shows one of the most satisfactory types, its boards being planed and
moulded as shown. The other two examples are more common. The boarding at
B is rebated, whilst at C each board overhangs its lower neighbour. The
boards for C and D are always cut tapered as indicated.
[Illustration: Fig. 343.--Weather Boards.]
[Illustration: Fig. 344.--Ladder Rungs.]
The end grain is usually protected by nailing on a strip of timber,
chamfered on both edges.
LADDERS.--Fig. 344 illustrates the method of fastening the rung (or
stave) of a ladder to the side. At A the common method is shown, the
stave being simply driven into the hole and wedged. At B a much better
but more expensive method of construction is given. The stave here is
socketed and the pin turned to a smaller diameter. In both cases the
rung, or stave, is painted before being driven into the side and wedged.
[Illustration: Fig. 345.--Cornice Pole Joint.]
[Illustration: Fig. 346.--Veneer Keying.]
Ladder sides are made in two distinct ways. One method is known as "a
plank side," the side being cut from a plank as shown at the section D;
the other method is called "a pole side," and is constructed by cutting a
straight larch pole in half and using half of the pole for each side of
the ladder, as at section C.
HINGED CORNICE POLES.--Fig. 345 shows a hinged joint for cornice poles
and should be of interest to those who are frequently removing from house
to house. The joint will adapt itself to fit any bay window (even a
square bay) and it is formed by turning and cutting the two pieces shown.
To fix a cornice pole to a bay window one of these joints is required for
each angle of the bay, the pole being cut into suitable lengths and fixed
to the hinged joints by the use of the dowel screw and a little hot
glue. It is perhaps needless to remark that the diameter of the joint
should be of the same diameter as the cornice pole, to enable the rings
to easily slide over the surface.
For fastening a turned ornament (or "finial") to the end of a cornice
pole a double pointed screw (known in the trade as a "dowel screw") is
used, one half of which is screwed into each part of the pieces to be
joined.
VENEER KEYING.--Fig. 346 illustrates the method of strengthening the
corners of boxes which are made of 1/4-in. or 3/8-in. timber, by securing
the corners with veneer keys. The box is mitred and glued in the usual
manner, and after allowing sufficient time for the glue to set, saw kerfs
are made as shown at _a a_. A piece of thin saw-cut veneer is afterwards
glued into the saw kerfs, and when dry the face is levelled off flush.
This method is often used previous to veneering the face side of the box
with rare veneers, and it is also useful for repair work. Note that the
saw cuts are made at an angle. Small picture frames are sometimes keyed
instead of nailed.
MUNTIN AND SKIRTING JOINT.--In the case of panelled rooms it is usually
necessary to scribe the muntins (or uprights) to the skirting. The method
is shown in Fig. 347. The bead moulding of the skirting is only partly
removed, as indicated, leaving a solid portion to which the muntin is
skew-nailed.