THE COMMON JOINTS.
Wherever two or more pieces of wood are fastened together we have what
is properly called joinery. In common usage the term indicates the
framing of the interior wood finish of buildings and ships, but it is
also used to include cabinet-making, which is the art of constructing
furniture, and even the trades of the wheelwright, carriage-maker, and
cooper. Since joinery involves the constant use of joints, a reference
list of them, with illustrations, definitions, uses, and directions
for making typical ones may be of convenience to workers in wood.
HEADING JOINTS
_No. 1. A lapped and strapped joint_, Fig. 264, p. 177, is made by
laying the end of one timber over another and fastening them both
together with bent straps on the ends of which are screws by which
they may be tightened. It is a very strong joint and is used where the
beams need lengthening as in false work or in long ladders and flag
poles.
_No. 2. A fished joint_, Fig. 264, is made by butting the squared
ends of two timbers together and placing short pieces of wood or
iron, called fish-plates, over the faces of the timbers and bolting or
spiking the whole firmly together. It is used for joining timbers in
the direction of their length, as in boat construction.
_No. 3._ In a _fished joint_, Fig. 264, keys are often inserted between
the fish-plate and beam at right angles to the bolts in order
to lessen the strain that comes upon the bolts when the joint is
subjected to tension. In wide pieces and for extra strength, as in
bridge work, the bolts may be staggered.
_Nos. 4, 5, 6 and 7._ _A scarf or spliced joint_, Fig. 264, is made by
joining together with flush surfaces the ends of two timbers in such a
way as to enable them to resist compression, as in No. 4; tension,
as in No. 5; both, as in No. 6, where the scarf is tabled; or cross
strain as in No. 7. No. 4 is used in house sills and in splicing out
short posts, Nos. 5 and 6 in open frame work. _No. 7_ with or without
the fish-plate, is used in boats and canoes, and is sometimes called
a boat-builder's joint, to distinguish it from No. 4, a carpenter's
joint. A joint to resist cross strain is stronger when scarfed in
the direction of the strain than across it. No. 7 is the plan, not
elevation, of a joint to receive vertical cross strain.
BUTT JOINTS
_No. 8. A doweled butt-joint_, Fig. 264, is made by inserting, with
glue, dowel-pins into holes bored into the two members. The end of one
member is butted against the face or edge of the other. It is used in
cabinet-making where the presence of nails would be unseemly.
[Illustration: Fig. 246. Lay-out by Thru Dowling.]
In a doweled butt-joint the dowels may go clear thru the outside
member, and be finished as buttons on the outside, where they show.
To lay out this joint mark near the ends of the edges of the abutting
member, X, Fig. 246, center-lines A B. Draw on the other member Y, a
sharp pencil-line to which when the lines AB on X are fitted, X will
be in its proper place. Carry the line around to the other side of Y
and locate on it the proper centers for the dowel-holes E and F. Then
fasten on the end of X a handscrew in such a way that the jaws will
be flush with the end. With another handscrew, clamp this handscrew to
Y in such a way that the marks on the two pieces match, A to C and B
to D, Fig. 247. Bore at the proper places, E and F, holes directly thru
Y into X.
[Illustration: Fig. 247. Thru Boring for a Butt Joint.]
Fig. 248 illustrates the gluing together of a four-legged stand in
which the joints are made in this way. The cross-lap joints of
the stretchers are first glued together, then the other joints are
assembled without glue, to see that all the parts fit and finally two
opposite sides are glued at a time. Pieces of paper are laid inside
the gluing blocks to prevent them from sticking to the legs.
[Illustration: Fig. 248. Gluing-Up a Four-Legged Stand.]
In case the dowels are to be hidden the chief difficulty is to locate
the holes properly. One method of procedure is as follows: To dowel
the end of one member against the face of the other as a stringer into
a rail or a rail into a table leg, first lay out the position of the
dowels in the end of the first member, X, Fig. 249. Gage a
center-line, A B, across this end lengthwise, locate the centers of the
dowel-holes, and square across with a knife point, as CD and EF. Gage
a line on the other member to correspond with the line AB. On the
face so gaged, lay the first member on its side so that one arris lies
along this gaged line and prick off the points D and F, to get the
centers of the dowel-holes.
[Illustration: Fig. 249. Laying out a Dowel Joint.]
If, as is usual, there are a number of similar joints to be made, a
device like that shown in Fig. 249 will expedite matters. 1 and 2
are points of brads driven thru a piece of soft wood, which has been
notched out, and are as far apart as the dowels. A-1 is the distance
from the working edge of the rail to the first dowel. The same measure
can be used from the end of the leg.
When the centers are all marked, bore the holes. Insert the dowels
into the holes and make a trial assembly. If any rail is twisted from
its proper plane, note carefully where the error is, take apart,
glue a dowel into the hole, that is wrong, pare it off flush with the
surface, and re-bore in such a place that the parts, when assembled
will come up true. When everything fits, glue and clamp together.
_No. 9. A toe-nailed joint_, Fig. 264, is made by driving nails
diagonally thru the corners of one member into the other. It is used
in fastening the studding to the sill in balloon framing.
_No. 10. A draw-bolt joint_, Fig. 264, is made by inserting an iron
bolt thru a hole in one member and into the other to meet a nut
inserted from the side of the second member. It is very strong and is
used in bench construction, wooden machinery, etc.
_No. 11. A plain butt-joint_, Fig. 264, is one in which the members
join endwise or edgewise without overlapping. It is used on returns as
in ordinary boxes and cases.
_No. 12. A glued and blocked joint_, Fig. 264, is made by gluing and
rubbing a block in the inside corner of two pieces which are butted
and glued together. It is used in stair-work and cabinet-work, as in
the corners of bureaus.
_No. 13. A hopper-joint_, Fig. 264, is a butt-joint, but is peculiar
in that the edges of the boards are not square with their faces
on account of the pitch of the sides. It is used in hoppers, bins,
chutes, etc. The difficulty in laying out this joint is to obtain the
proper angle for the edges of the pieces. This may be done as follows:
After the pieces are planed to the correct thickness, plane the upper
and lower edges of the end pieces to the correct bevel as shown by the
pitch of the sides. Lay out the pitch of the sides of the hopper on
the outside of the end pieces. From the ends of these lines, on the
upper and lower beveled edges score lines at right angles with the
knife and try-square. Connect these lines on what will be the inside
of the hopper. Saw off the surplus wood and plane to the lines thus
scored. The side pieces may be finished in the same way, and the parts
are then ready to be assembled.
HALVING-JOINTS
A halved joint is one in which half the thickness of each member is
notched out and the remaining portion of one just fits into the notch
in the other, so that the upper and under surfaces of the members are
flush.
_No. 14. A cross-lap joint_, Fig. 264, is a halved joint in which both
members project both ways from the joint. This is a very common joint
used in both carpentry and joinery, as where stringers cross each
other in the same plane.
The two pieces are first dressed exactly to the required size, either
separately or by the method of making duplicate parts, see Chap. IX,
p. 204. Lay one member, called X, across the other in the position
which they are to occupy when finished and mark plainly their upper
faces, which will be flush when the piece is finished. Locate the
middle of the length of the lower piece, called Y, on one arris, and
from this point lay off on this arris half the width of the upper
piece, X. From this point square across Y with the knife and
try-square. Lay X again in its place, exactly along the line just
scored. Then mark with the knife on Y the width of X, which may then
be removed and the second line squared across Y. From these two lines
square across both edges of Y to approximately one-half the thickness.
Now turn X face down, lay Y on it, and mark it in the same way as Y.
Set the gage at one-half the thickness of the pieces, and gage between
the lines on the edges, taking care to hold the head of the gage
against the marked faces. Then even if one piece is gaged so as to
be cut a little too deep, the other will be gaged so as to be cut
proportionately less, and the joint will fit.
Cut a slight triangular groove on the waste side of the knife-marks,
Fig. 91, p. 66, saw accurately to the gaged lines, and chisel out the
waste as in a dado, see Figs. 70 and 71, p. 56.
The bottom of the dado thus cut should be flat so as to afford surface
for gluing. When well made, a cross-lap joint does not need to be
pounded together but will fit tight under pressure of the hands.
_No. 15. A middle-lap joint or halved tee_, Fig. 265, is made in the
same way as a cross-lap joint, but one member projects from the joint
in only one direction, it is used to join stretchers to rails as in
floor timbers.
_No. 16. An end-lap joint_, Fig. 265, is made in the same way as a
cross-lap joint except that the joint is at the end of both members.
It is used at the corners of sills and plates, also sometimes in
chair-seats.
To make an end-lap joint, place the members in their relative
positions, faces up, and mark plainly. Mark carefully on each member
the inside corner, allowing the end of each member slightly (1/16")
to overlap the other. Square across at these points with a sharp knife
point, on the under side of the upper member, and on the upper side of
the lower member. Now proceed as in the cross-lap joint, except
that the gaged line runs around the end and the cutting must be done
exactly to this line.
_No. 17._ In an _end-lap joint on rabbeted pieces_, Fig. 265, the
joint must be adapted to the rabbet. The rabbet should therefore be
plowed before the joint is made. The rabbet at the end of the piece X
is cut not the entire width of the piece Y, but only the width of the
lap,--c-f=a-e. This joint is used occasionally in picture-frames.
_No. 18. A dovetail halving or lap-dovetail_, Fig. 265, is a
middle-lap joint with the pin made dovetail in shape, and is thus
better able to resist tension. It is used for strong tee joints.
_No. 19. A beveled halving_, Fig. 265, is made like a middle-lap joint
except that the inner end of the upper member is thinner so that the
adjoining cheeks are beveled. It is very strong when loaded above. It
was formerly used in house framing.
MODIFIED HALVING JOINTS
_No. 20. A notched joint_, Fig. 265, is made by cutting out a portion
of one timber. It is used where it is desired to reduce the height
occupied by the upper timber. Joists are notched on to wall plates.
_No. 21. A checked joint or double notch_, Fig. 265, is made by
cutting out notches from both the timbers so as to engage each other.
It is used where a single notch would weaken one member too much.
_No. 22. A cogged or corked or caulked joint_, Fig. 265, is made by
cutting out only parts of the notch on the lower piece, leaving a
"cog" uncut. From the upper piece a notch is cut only wide enough to
receive the cog. A cogged joint is stronger than a notched because
the upper beam is not weakened at its point of support. It is used in
heavy framing.
_No. 23. A forked tenon joint_, Fig. 265, is made by cutting a fork in
the end of one member, and notching the other member to fit into
the fork, so that neither piece can slip. It is used in knock-down
furniture and in connecting a muntin to a rail, where it is desired
that the muntin should run thru and also that the rail be continuous.
_No. 24. A rabbet or rebate or ledge joint_, Fig. 266, is made by
cutting out a portion of the side or end of a board or timber X to
receive the end or side of another, Y. It may then be nailed from
either the side or end or from both. The neatest way in small boxes is
from the end, or better still it may be only glued.
_No. 25. A dado or grooved joint_, Fig. 266, is made by cutting in one
member a groove into which the end or edge of the other member fits.
Properly speaking a groove runs with the grain, a dado across it, so
that the bottom of a drawer is inserted in a groove while the back of
the drawer is inserted in a dado. Where the whole of the end of one
member is let into the other, such a dado is also called a housed
dado. Treads of stairs are housed into string boards.
To lay out a dado joint: After carefully dressing up both pieces to
be joined, locate accurately with a knife point, on the member to be
dadoed, called X, one side of the dado, and square across the piece
with a try-square and knife. Then locate the other side of the dado by
placing, if possible, the proper part of the other member, called
Y, close to the line drawn. If this method of superposition is not
possible, locate by measurement. Mark, with a knife point, on X, the
thickness thus obtained. Square both these lines as far across the
edges of X as Y is to be inserted. Gage to the required depth on both
edges with the marking-gage.
To cut the joint: First make with the knife a triangular groove on the
waste side of each line, as indicated in Fig. 91, p. 66, and starting
in the grooves thus made, saw with the back-saw to the gaged lines
on both edges. The waste may now be taken out either with a chisel or
with a router, Fig. 122, p. 83. The second member, Y, should just fit
into a dado thus made, but if the joint is too tight, the cheeks of
the dado may be pared with a chisel. In delicate work it is often wise
not to saw at all, but to use only the knife and chisel.
_No. 26. A dado and rabbet_, Fig. 266, is made by cutting a dado in
one member, X, and a rabbet on the other, Y, in such a way that the
projecting parts of both members will fit tight in the returns of
the other member. It is used in boxes and gives plenty of surface for
gluing.
_No. 27. A dado, tongue and rabbet_, Fig. 266, is a compound joint,
made by cutting a rabbet on one member, Y, and then a dado in this
rabbet, into which fits a tongue of the other member, X. It is used in
machine-made drawers.
_No. 28. A dovetail dado or gain_, Fig. 266, is made by cutting one or
both of the sides of the infitting member, Y, on an angle so that it
has to be slid into place and cannot be pulled out sidewise. It is
used in book-cases and similar work, in which the shelves are fixed.
To make this joint, first lay out the dovetail on the member to be
inserted, called Y, thus: Across one end square a line (A B, No.
28), at the depth to which this member is to be dadoed in. Set the
bevel-square at the proper angle for a dovetail, Fig. 250. Score this
angle on the edges of the member, as at C D. Cut a groove with a knife
on the waste side of A B. Saw to the depth A C, and chisel out the
interior angle A C D.
Then lay out the other member, X, thus: mark with the knife the proper
place for the flat side of Y, square this line across the face and on
the edges as for a simple dado. Lay out the thickness of Y on the face
of X by superposition or otherwise and square the face and edges, not
with a knife but with a sharp pencil point. Gage the required depth on
the edges. Now with the bevel-square as already set, lay out the angle
A C D on the edges of X, and across the face at C score a line with
knife and try-square. Cut out grooves in the waste for the saw as in
a simple dado, and saw to the proper depth and at the proper angle.
Chisel or rout out the waste and when complete, fit the pieces
together.
[Illustration: Fig. 250. Laying Out a Dovetail Joint.]
_No. 29. A gain joint_, Fig. 266, is a dado which runs only partly
across one member, X. In order to make the edges of both members flush
and to conceal the blind end of the gain, the corner of the other
member, Y, is correspondingly notched out. In book shelves a gain
gives a better appearance than a dado.
A gain joint is laid out in the same way as the dado, except that the
lines are not carried clear across the face of X, and only one edge is
squared and gaged to the required depth. Knife grooves are made in the
waste for starting the saw as in the dado. Before sawing, the blind
end of the gain is to be chiseled out for a little space so as to give
play for the back-saw in cutting down to the required depth. To avoid
sawing too deep at the blind end, the sawing and chiseling out of
waste may be carried on alternately, a little at a time, till the
required depth is reached. It is easy to measure the depth of the cut
by means of a small nail projecting the proper amount from a trial
stick, Fig. 251. The use of the router, Fig. 122, p. 83, facilitates
the cutting, and insures an even depth.
[Illustration: Fig. 251. Depth-gage for Dado.]
MORTISE-AND-TENON JOINTS
The tenon in its simplest form is made by dividing the end of a piece
of wood into three parts and cutting out rectangular pieces on both
sides of the part left in the middle. The mortise is the rectangular
hole cut to receive the tenon and is made slightly deeper than the
tenon is long. The sides of the tenon and of the mortise are called
"cheeks" and the "shoulders" of the tenon are the parts abutting
against the mortised piece.
_No. 30. A stub mortise-and-tenon_, Fig. 266, is made by cutting only
two sides of the tenon beam. It was formerly used for lower ends of
studding or other upright pieces to prevent lateral motion.
_No. 31. A thru mortise-and-tenon_, Fig. 266, is made by cutting the
mortise clear thru one member and by cutting the depth of the tenon
equal to or more than the thickness of the mortised member. The cheeks
of the tenon may be cut on two or four sides. It is used in window
sashes.
A thru mortise-and-tenon joint is made in the same way as a blind
mortise-and-tenon (see below), except that the mortise is laid out on
the two opposite surfaces, and the boring and cutting are done from
both, cutting first from one side and then from the other.
_No. 32. A blind mortise-and-tenon_, Fig. 266, is similar to the simple
mortise-and-tenon described in 30. The tenon does not extend thru the
mortised member and the cheeks of the tenon may be cut on two or four
sides.
To make a blind mortise-and-tenon, first make the tenon thus: Locate
accurately with a knife point the shoulders of the tenon and square
entirely around the piece. On the working edge near the end mark the
thickness of the tenon. Set the marking-gage at the proper distance
from the working face to one cheek of the tenon and gage the end and
the two edges between the end and the knife-lines. Reset the gage to
mark the thickness of the tenon and gage that in the same way from the
working face. Then mark and gage the width of the tenon in the same
way. Whenever there are several tenons of the same size to be cut,
they should all be laid out together, that is the marking-gage set
once to mark all face cheeks and once to mark all back cheeks. If a
mortise-gage is available, use that. Always mark from the working face
or working edge. Cut out a triangular groove on the waste side of the
knife lines (at the shoulders) as in cutting a dado, Fig. 91, p. 66.
In cutting the tenon, first rip-saw just outside the gaged lines,
then crosscut at the shoulder lines. Do all the rip-sawing before the
crosscutting. If the pieces are small the back-saw may be used for
all cuts. It is well to chamfer the arrises at the end of the tenon to
insure its starting easily into the mortise.
Locate the ends of the mortise and square lines across with a sharp
pencil in order to avoid leaving knife marks on the finished piece.
Then locate the sides of the mortise from the thickness of the tenon,
already determined, and gage between the cross lines. As in the case
of like tenons, if there are a number of mortises all alike, set the
gage only twice for them all.
In _cutting the mortice_, first fasten the piece so that it will rest
solid on the bench. This may be done either in a tail vise or by a
handscrew, or by clamping the bench-hook firmly in the vise in such a
way that the cleat of the bench-hook overhangs the piece. Then tap
the bench-hook with a mallet and the piece will be found to be held
tightly down on the bench. See Fig. 76, p. 58.
It is common to loosen up the wood by first boring a series of
adjoining holes whose centers follow the center-line of the mortise
and whose diameter is slightly less than the width of the mortise.
Take care to bore perpendicularly to the surface, see Fig. 137, p. 86,
and no deeper than necessary. Dig out the portions of wood between the
auger holes and chisel off thin slices, back to the gage-lines and
to the knife-lines, taking care all the time to keep the sides of the
mortise perpendicular to the face. This may be tested by placing the
chisel against the side of the mortise and standing alongside it a
try-square with its head resting on the surface.
Finally test the tenon in the mortise noting carefully where it
pinches, if anywhere, and trim carefully. The tighter it fits without
danger of splitting the mortised member, the stronger will be the
joint.
Many prefer to dig mortises without first boring holes. For this
purpose a mortise-chisel, Fig. 68, p. 54, is desirable. The method
is to begin at the middle of the mortise, placing the chisel--which
should be as wide as the mortise--at right angles to the grain of the
wood. Chisel out a V shaped opening about as deep as the mortise, and
then from this hole work back to each end, occasionally prying out the
chips. Work with the flat side of the chisel toward the middle except
the last cut or two at the ends of the mortise.
_No. 33._ In a _mortise-and-tenon joint on rabbeted pieces_, Fig. 266,
the tenon is as much shorter on one side than the other as the rabbet
is wide. In Fig. 33, ab=cd.
_No. 34. A wedged mortise-and-tenon joint_, Fig. 266, is a thru joint
in which after the tenon is driven home, wedges are driven in between
the tenon and the sides of the mortise. The wedges are dipped in glue
or white lead before being inserted. The sides of the mortise may be
slightly dovetailed. It is used to keep a tenon tightly fixed as in
wheel spokes.
_No. 35. A wedged mortise-and-tenon joint_, Fig. 266, may also be made
by driving the wedges into saw kerfs in the tenon instead of along
its sides as in No. 34. It is used in ornamental joints as well as in
carpentry.
_No. 36. A fox-tail tenon_, Fig. 266, is a blind mortise-and-tenon in
which the mortise is made slightly wider at the bottom than the width
of the tenon. Wedges are driven into saw kerfs in the tenon before
inserting into the mortise; then when it is driven home the wedges
spread out the tenon and make it fill out the mortise. It is used in
strong doors and also where the mortised member is already in place so
that a wedged mortise-and-tenon is impossible.
_No. 37. A dovetail mortise-and-tenon_, Fig. 266, is a thru
mortise-and-tenon beveled on one side so as to form half a dovetail.
The corresponding side of the mortise is also beveled and made wide
enough so that when the tenon is pressed well up against its beveled
side a wedge may be driven into the space left on the straight side.
It is used to tenon a beam into a post especially where the post is
fixed against a wall. It is also used in machinery frames which are
made of wood.
_No. 38. A pinned mortise-and-tenon_, Fig. 267, is one in which a pin
is driven thru holes bored thru the mortised beam and thru the tenon
to keep them from drawing apart. It is used in heavy framing as in
bridges, in wagon-making, in window-sash, etc.
_No. 39. A keyed mortise-and-tenon_, Fig. 267, is one in which the
tenon protrudes thru the mortise far enough to receive a removable
key and thus be drawn up tight to the mortised member. It is used in
work-benches and in ornamental joints like knock-down bookcases and in
other mission furniture.
The keyed mortise-and-tenon is made as in a thru mortise-and-tenon,
except that before cutting the tenons the holes for wedges should be
laid out thus: measuring from the shoulder of the tenon, locate by
superposition or measurement the outside of the mortised member.
Deduct from this 1/16" and square a fine pencil-line across the face
and opposite side. This line will be the inside of the hole for the
wedge, and the 1/16" is deducted to make sure that the key wedges
against the mortised member. On the upper surface of the tenon, lay
off toward the end the width of the wedge at this point, A B, Fig.
252, and square across. On the under surface, lay off the width of the
wedge at this point, C D, and square across.
[Illustration: Fig. 252. Keyed Mortise-and-Tenon Joint.]
Gage the sides of the wedge hole on both upper and lower surfaces of
the tenon. After cutting the mortise and tenon, bore and chisel out
the hole for the wedge, taking care to cut the side toward the end on
a bevel to fit the wedge.
_No. 40. A tusk tenon or shoulder tenon_, Fig. 267, is one in which
the tenon proper is quite thin but is reinforced by a thicker shoulder
called a "tusk." The upper shoulder is beveled. The object of this
form is to weaken the mortised member as little as possible but at the
same time to increase the strength of the tenon. It is used in joining
tail beams to headers in floor framing.
_No. 41. A double mortise-and-tenon_, Fig. 267, consists of two tenons
side by side in one piece fitting into two corresponding mortises. It
is used in joinery, as in door-frames, but not in carpentry.
_No. 42. A haunched mortise-and-tenon_, Fig. 267, is made by cutting
away part of the tenon so that that part of it will be much shorter
than the rest. The haunch gives the tenon great lateral strength
and saves cutting so large a mortise hole. It is used in panel
construction, as where the rails are joined to the stiles of doors.
First plow the groove in all the members. This should be of the same
width as the thickness of the tenons, which is ordinarily one-third of
the thickness of the frame. The groove is approximately as deep as
it is wide. Lay out and cut the tenon the width of the entire piece,
minus, of course, the depth of the groove. The mortise should not come
too near the end, or the portion of wood outside it will shear out.
Hence the tenon is narrowed on the outside enough to insure strength
in the mortised piece. The rule is that the tenon should be one-half
the width of the rail, minus the groove. But enough of the tenon is
left full width to fill up the groove at the outer end of the mortised
piece. This is called the _haunch_. The width of the mortise is equal
to the width of the groove, its length to the width of the tenon.
Before assembling the panel frame, put soap or tallow on the corners
of the panel to prevent its being glued to the frame.
_No. 43. Table or taper haunching_, Fig. 267. Sometimes, as in table
construction, for the sake of stiffening the rail, or in places where
it is desirable that the haunch does not show, the haunch is beveled
from the tenon to the edge of the rail.
_No. 44. A bare-faced tenon_, Fig. 267, is one in which a cheek is
cut from only one side. It is used where the rail is thinner than the
stile and it is desirable to keep the mortise near the middle of the
stile.
_No. 45. A housed mortise-and-tenon_, Fig. 267, is one in which the
whole of the end of one member is let in for a short distance or
"housed" into the other. It is common in grill work and in railings.
_No. 46. A slip-joint or end or open mortise-and-tenon_, Fig. 267, is
what would remain if a mortised member were sawn off along one side
of the tenoned member. Window screens and other light frames such as
those for slates and for printing photographs have this joint. This
joint multiplied is used for small machine-made boxes, and is then
called _corner locking_.
DOVETAIL JOINTS
"Dovetail" refers to the shape of the projections of one member, when
looked at broadside. These projections are called dovetails, or merely
tails.
The projections on the other member are called tenons or pins, and the
spaces between both tails and tenons are called mortises or sockets.
_No. 47. A thru single dovetail_, Fig. 267, is similar to a slip-joint
except that instead of a tenon there is a dovetail. It is used in
window-sashes.
_No. 48. A thru-multiple dovetail_, Fig. 267, consists of a series of
alternate tails and tenons which fit one another closely. It is used
in tool-chests and in other strong as well as fine boxes.
To make a thru multiple dovetail joint, first square lines with a
sharp pencil around the ends of both members to locate the inner ends
of the dovetails and the pins, d e on X, Fig. 250, and l m on Y. The
distance of this line from the ends of each member may, if desired,
be slightly (1/32") greater than the thickness of the other member.
Divide this line, d e, on the member to be dovetailed, X, into as many
equal spaces as there are to be tails (dovetails). From the division
points of these spaces, a b c, to the right and left lay off one-half
of the greatest width of the mortises to be cut out, and also the same
distance from d and from e, as at f f f f and g g g g.
The strongest arrangement of dovetails is to make them equal in width
to the spaces between them, as in No. 48, p. 267. For the sake of
appearance they may be as much as four times as wide as the spaces,
but ordinarily should not be wider than 1-3/4".
Set the bevel-square so that it will fit the angle A B C, Fig. 250, p.
159, in a right angle triangle, the long side of which is 3" and the
short side 5/8". This is approximately an angle of 80° or a little
more than one to five. From the points f f f f and g g g g lay off
this angle to the end of the piece. Carry these lines across the end
at right angles to the surface, h i, Fig. 250, and repeat the dovetail
angles on the other surface. Mark plainly the parts to be cut out (the
mortises), as on X in Fig. 250. Score with a knife point the inner
ends of the mortises, d to f, g to f, etc., and across the edge at d
and at e. With a dovetail-saw, Fig. 93, p. 66, cut on the mortise side
of each line down to the cross line, d-e, and also along the cross
line from d to f and e to g. Chisel out the mortises taking care to
keep the line d-e straight and square. The ends (not the sides) of the
mortises may be slightly undercut to insure a tight fit.
Fasten the other member, Y, upright in the vise so that the end to be
tenoned will be flush with the top of the bench, and with the working
face toward the bench. Place on it the working face of X, (the member
already dovetailed,) taking care that the inner ends of the mortises
are in line with the working face of Y, and that the edges of the two
members are in the same plane, as X on Y in Fig. 250. Scribe with a
knife point along the sides of the tails on the end of Y (f'-j' and
g'-h'). Remove Y from the vise and square down these lines to the
cross line l-m (j'-n and h'-o). Score with the knife point the inner
ends of the mortises of Y (n-o). Saw with a dovetail-saw on the
mortise sides of these lines, chisel out the mortises and fit the
parts together. When glued together, the joints should be dressed off.
Where there are several parts to be made alike, it is necessary to lay
out the dovetails on only one X member. This may be used as a templet
for laying out the others and they can then be sawn separately. Or all
the X members may be clamped carefully together, with one X already
laid out, rights and lefts in pairs, and edges and ends flush, the
depth mark gaged all around, and then all sawn at once.
The dovetail joint is also made by first laying out and cutting the
members having the pins, and then superposing this on the piece to be
dovetailed, and scribing around the pins.
_No. 49. A lap or half blind dovetail_, Fig. 267, is a dovetail joint
in which the tails on one member do not extend entirely thru the
thickness of the other member. It is used in joining the sides to the
fronts of drawers and other fittings where only one side is seen.
If the joint is to be used for a drawer front, the groove for the
drawer bottom should be cut or at least laid out before laying out the
joint. See also drawers, p. 190, and Fig. 287, p. 191. On the end of
the drawer front, gage the depth of the joint. Gage the same distance
on both broad surfaces of the drawer sides, marking from the front
ends. Lay out and cut the dovetails as in a thru dovetail joint,
taking especial care to have the groove for the bottom completely
within the lower tail. Take care also to make the sides, one right and
one left, not both alike, so that the groove will come inside. Lay out
the drawer front by superposing the dovetailed side, X, on the end of
the front, Y, as in a thru dovetail. Saw and chisel out the mortises
and fit together.
_No. 50. A stopped lap dovetail_, Fig. 267, is one in which neither
the tails nor the pins extend thru the other members. Hence the joint
is concealed. The lap may be rounded. It is used in fine boxes, trays,
etc.
_No. 51. The blind miter or secret dovetail_, Fig. 267, is a joint in
which only part, say one-half, of both boards is dovetailed, the outer
portion being mitered. The edges of the boards are also mitered right
thru for a short distance so that when finished the dovetails are
invisible. It is used in highly finished boxes.
BEVELED JOINTS
A beveled joint is made by beveling the members so that the plane of
the joint bisects the angle at which the members meet. This is called
the "miter" and may be 45 degrees or any other angle. It is a neat but
weak joint unless reinforced by a spline, nails, or in some other way.
[Illustration: Fig. 253. Gluing Together a Picture-Frame (See also
Fig. 254.)]
_No. 52. A plain miter_, Fig. 268, is a joint where the beveled edges
or ends abut and are simply glued or nailed together. It is commonly
used in picture-frames, inside trim, columns, boxes, and taborets,
four or more sided.
[Illustration: Fig. 254. Picture-Frame-Clamp.]
For gluing mitered frames, the most convenient way is with the aid of
the picture-frame-vise, Fig. 172, p. 101. Nails are driven or splines
inserted as soon as each joint is glued. Where this vise is not
available, an ordinary metalworking vise may be used, as follows:
Fasten one member, X, face side up, firmly in the vise. Bore holes in
the other member, Y, at the proper places for the nails. Insert nails
in the holes, apply the glue to both mitered surfaces, place the glued
surfaces together, letting Y project about 1/8" beyond X. A convenient
way to hold Y in place is in the left hand, palm up, while the left
forearm rests upon X. Drive one of the nails home, and continue
driving until the parts exactly fit. Then drive home the other nail.
Now fasten together in the same way the other two members of the
picture-frame, and then, one at a time, the third and fourth joint.
This is the method used in picture-frame factories, and when once
learned is very simple.
[Illustration: Fig. 255. Picture-Frame-Clamp. (See also Fig. 254.)]
For gluing together at once all the members of a mitered frame, the
device shown in Fig. 253 is convenient and is easily made. Out of two
pieces of wood somewhat longer than the two end pieces of the frame,
gains are cut of the exact length of the ends, as shown in the
illustration. By applying two clamps lengthwise on the frame, all four
joints may be glued together at once. If the frame does not come up
square, it may be squared by means of a temporary brace, A, in Fig.
253.
The device shown in Figs. 254 and 255, is also an easily made and
efficient tool. At least the small pieces, which receive the corners
of the frame, should be made of hard wood such as maple. It is
self-adjusting but care must be taken not to buckle the parts of a
narrow frame by over pressure. It is well to soap or oil the corner
pieces to prevent their being glued to the frame.
[Illustration: Fig. 256. Gluing up a Column Joint. (Pinch-Dogs at Top
of Joints.)]
In gluing together long mitered joints, in six or eight sided taborets
or columns, in which the members meet edgewise, one method is to wrap
a few turns of bale wire around the parts and drive in wedges under
the wire to obtain pressure, Fig. 256. Another method is to wrap a
stout rope, such as is used for window weights, around all the pieces,
properly set up, then to tighten it by twisting it with a stick thru
a loop, Fig. 257. A still more effective way is by means of the Noxall
Column Clamp, a powerful device, used chiefly for gluing up such
pieces as the pillar of a centrally supported table, Fig. 259. Care
must be taken with all these devices to protect the corners, unless
they are to be rounded off afterward. A good way to protect them is
with pieces fastened together in the shape shown in Fig. 258, b, and
Fig. 257, the interior angle being equal to the exterior angle of the
piece to be glued. In the case of a taboret with slender legs, care
must be taken to insert blocks between the separate legs as well, to
brace them apart and to keep them from bending under the pressure.
These methods have the advantage that they are speedy, since all the
pieces go together at once; but unless the pieces fit exactly the
joints will not close.
Another method is to glue and clamp the pieces of the taboret together
two by two, using blocks as shown in Fig. 258, _a_. Care should be
taken to put the pressure of the handscrews as far out as possible so
as to be sure that the outside of the joint closes. This method has
the advantage that, as only one joint is glued at a time, the work
can be done more deliberately. Moreover, if when three pairs of a
six-sided taboret are together, the other three joints do not fit
exactly, they can then be refitted.
Another method is to glue pieces of soft wood on the exterior of each
pieces as shown in Fig. 258, _c_. These blocks should be of such shape
that the opposite sides of each pair are parallel. When the glue is
dry, they are used as corners on which to clamp the handscrews. This
method has the disadvantage that the blocks may break loose at a
critical moment.
[Illustration: Fig. 257. One Method of Gluing up a Six-Sided Taboret.]
In addition to any of these methods of tightening the joints, to make
sure that the ends of the joints close tight, pinch-dogs, Fig. 178, p.
103, may be driven into the end grain, and corrugated fasteners, Fig.
228, p. 125, also driven into the ends, make the joint quite secure.
_No. 53. A doweled miter_, Fig. 268, is one in which one or more
dowels are inserted and glued into holes bored into the beveled edges.
It may be used instead of nails, as in large picture frames.
_No. 54. A spline or tongue miter_, Fig. 268, is one which has a
spline or tongue inserted at right angles to the joint. Since it
furnishes more gluing surface, it is stronger than a plain miter.
_No. 55. A slip-feather or slip-key miter_, Fig. 268, is one which is
strengthened by a slip of hardwood glued into a saw kerf cut across
the mitered angle. It is used in picture-frames and in boxes.
_No. 56. A slip-dovetail miter_, Fig. 268, is one in which a
trapezoidal shaped key is inserted in a dovetail socket cut straight
across the miter. When dressed off, it gives the appearance of a
dovetail on each face. It is used for the same purpose as a spline
miter.
_No. 57. A double dovetail keyed miter_, Fig. 268, is one in which a
double dovetail key made of hard wood is inlaid across the joint. This
is a favorite joint with Oriental joiners.
[Illustration: Fig. 258. Devices for Gluing Beveled Edges.]
_No. 58. A ledge and miter or lipped miter joint_, Fig. 268, is made
by rabbeting and mitering the boards to be joined so that the outer
portion of the two boards meet in a miter. It is strong and good
looking and may be glued or nailed. It is used for fine boxes.
_No. 59. A stopped miter_, Fig. 268, is useful for joining pieces of
different widths, when both sides can be seen.
[Illustration: Fig. 259. Column-Clamp.]
_No. 60. A double-tongue miter_, Fig. 268, is made by cutting on the
adjoining edges tongues which engage in each other. It is used in high
class joinery, on members that join lengthwise of the grain.
_No. 61. A stretcher joint_, Fig. 268, is a slip joint in which one or
both sides is mitered. It is used in frames for stretching canvass for
paintings by driving wedges from the inside. Two forms are shown in
61a and 61b.
_No. 62. A strut joint_, Fig. 268, is a form of miter joint used in
making trusses.
_No. 63 and 64. A thrust joint or tie joint or toe joint_, Fig. 268,
is one in which two beams meet at an oblique angle, one receiving the
thrust of the other. The toe may be either square as in 63, or oblique
as in 64. The pieces are bolted or strapped together with iron. It is
used for the batter braces of bridges.
_No. 65. A plain brace joint_, Fig. 269, is one in which the brace is
simply mitered and nailed into place. It is used for bracket supports.
No. _66. A housed brace joint_, Fig. 269, is a joint in which the
brace is housed into the rectangular members except that the outer end
of the mortise is cut at right angles and the inner end diagonally to
receive the brace which is cut to correspond. It is much stronger than
65.
_No. 67. An oblique mortise-and-tenon or bevel-shoulder joint_,
Fig. 269, is one in which the shoulders of the tenoned beam are cut
obliquely and its end is cut off at right angles. The cheeks of the
mortise are correspondingly sunk. By these means the tenon prevents
lateral motion while the whole width of the beam presses against the
abutment. Thus a much larger bearing surface is obtained. The whole is
bolted or strapped together. It is used in heavy truss work.
_No. 68. A bridle joint_, Fig. 269, is an oblique joint in which a
bridle or "tongue" is left in an oblique notch cut out of one beam.
Over this tongue is fitted a grooved socket cut obliquely in the other
beam. It is used in truss construction.
_No. 69. A bird's mouth joint_, Fig. 269, is an angular notch cut in a
timber to allow it to fit snugly over the member on which it rests. It
is used in rafters where they fit over the plate.
_No. 70. A plain or rubbed or squeezed or glue joint_, Fig. 269, is
one in which the edges of two boards are glued and rubbed together
tight. It is used in table-tops, drawing-boards, etc.
To make this joint, first the boards are all laid down flat, side by
side, and arranged in the proper order. Three considerations determine
what this order is to be: (1), if the grain is of prime importance, as
in quartered oak, then the boards are arranged so as to give the best
appearance of the grain. (2), if possible, the boards should be so
arranged that the warping of each board shall counteract that of the
adjacent ones. For this purpose the boards are so laid that the annual
rings of one shall alternate in direction with the annual rings of the
next, Fig. 280, a, p. 188. (3), if possible, the boards should be so
arranged that after being glued together they can all be planed smooth
in the same direction. When the above requirements have been met so
far as possible, this order should be marked on adjoining edges for
later identification. The edges of the boards to be joined should be
finished with a jointer.
There are two principal methods of gluing edge-to-edge joints, rubbing
and squeezing. In a rubbed joint, the surfaces to be joined should be
planed so as to meet thruout exactly. After properly planing one edge
of each board, keep one board in the vise, jointed edge up, and place
its to-be neighbor in position upon it. Then use these four tests for
an exact fit. (1) Sight down the end to see that the faces lie in the
same plane. (2) Examine the crack from both sides. Be sure that both
ends touch. Test this by pulling down hard on one end of the upper
board and noticing if the other end is still in contact. If the other
end opens, swing the upper board horizontally on the lower board to
see where the high place is and then correct it. (3) See if the upper
board stands firmly on the lower board by feeling gently to see if it
rocks, or by rapping lightly the lower board. (4) Slide the top board
slowly on the lower one to see if it adheres or "sucks."
[Illustration: Fig. 260. Applying Glue for an Edge-to-Edge Joint.]
After the pieces have been warmed, which should be done if possible,
the glue is spread on them, Fig. 260, and they are then rubbed slowly
back and forth in the direction of the grain, pressure being applied
by the hand and care being taken not to open the joint in the least.
As the glue sets, the rubbing becomes more difficult. It should be
stopped when the boards are in their proper relative positions. In
rubbing together the edges of two boards, handscrews may be fastened
to one in such a way that their jaws serve as guides for the other
board to slide between, Fig. 261. Care must be taken to make the jaws
of the handscrew diverge enough not to pinch the upper board.
[Illustration: Fig. 261. Rubbing a Glued Joint.]
Another method is to clamp a spare board alongside and projecting
above the lower board. This spare board acts as a guide against which
the upper board can be pushed as it is rubbed back and forth. The
rubbed joint is especially suitable for short boards.
In joining long boards, a squeezed joint is common. In this case, the
edges are planed so as to be very slightly concave from end to end.
The object of this is to counteract the subsequent shrinkage which is
likely to take place at the ends of the boards before it does at the
middle. The pressure of the clamps may be depended upon to close up
the middle, and, especially if dowels are inserted, as in No. 75, the
joint will be strong enough to resist the elasticity of the boards.
When the fit is good, warm the wood if possible, prepare the clamps,
put a thin film of glue over both edges which are to be together,
apply the clamps rapidly, keeping the faces flush, and set away to dry
for at least six hours. Then another piece may be added in the same
manner. If the boards are thin and wide, and therefore likely to
buckle, they may first be handscrewed to cross-strips to prevent their
buckling. The cross-strips are, of course, slightly shorter than the
combined width of the boards so that the full pressure of the clamps
may come on the glued joint.
_No. 71. A rebated, rabbeted or fillistered joint_, Fig. 269. Rebating
is the cutting of a rectangular slip out of the side of a piece of
wood. The re-entering angle left upon the wood is called the rebate or
rabbet. A rebated joint, then, is one in which corresponding rebates
are taken off edges so that the joined boards may overlap. It is used
in flooring and siding.
A board is rebated and filleted when two adjoining rebates are filled
with a fillet.
[Illustration: Fig. 262. Edge-to-Edge Joint, Doweled.]
_No. 72. A matched or tongue-and-groove joint_, Fig. 269, is made
by making a projection or "tongue" in the center of the edge of one
board, and a corresponding groove in the center of the other so that
they will match together. When used for flooring, the lower side of
the grooved board is slightly rebated so that the upper edges will
surely touch. This sort of flooring can be blind-nailed.
_No. 73. A beaded joint_, Fig. 269, is similar to a matched joint
except that a bead is worked on one edge to disguise the joint for
decorative purposes.
_No. 74. A spline-joint_, Fig. 269, is made by plowing corresponding
grooves in the edges to be joined and inserting a spline or
slip-feather. It is used in plank flooring.
_No. 75. A doweled joint_, Fig. 269, is made by jointing the two edges
carefully, boring holes opposite each other and inserting dowel pins
when the two edges are glued together. It is used in table tops, etc.
Where the boards are thick enough to allow it, a squeezed joint is
greatly strengthened by the insertion of dowels.
The essential point in inserting dowels is to have the holes for them
directly opposite one another and at right angles to the surface. The
following is a convenient method where boards are to be joined edge to
edge, Fig. 262. Place the two boards back to back in the vise with the
edges and ends flush. Determine approximately where the dowels are
to be inserted. With the gage, mark short lines at the points of
insertion in the center of each edge, gaging from the outside faces.
Across these lines score accurately with a try-square and knife. Then
bore the holes with a dowel-bit at the intersection of the lines, Fig.
263. If this is carefully done, the holes will be directly opposite
one another, and equidistant from the faces of both boards. All the
holes should be of equal depth, say 1", in order that the dowel-pins,
which should also be cut of equal lengths, may be interchangeable.
After boring, the holes may be slightly countersunk in order to insure
a tight joint and the easy slipping of the pins into place. The latter
result may also be obtained by slightly pointing the pins with a
dowel-pointer, Fig. 123, p. 83. It is also a wise precaution to cut a
small groove along the length of the pin to allow superfluous glue to
escape from the hole. The dowel should be dipped in glue and inserted
when the glue is applied to the joint.
[Illustration: Fig. 263. Boring for Dowels in an Edge-to-Edge Joint.]
THE COMMON JOINTS
REFERENCES:[*]
Rivington, Vol. I, pp. 57-77, 135-137, 238-242; Vol. II, pp. 291-295.
Adams, pp. 1-30.
Sickels, pp. 86-124.
Goss, pp. 128-152.
Ellis, pp. 135-151.
Barter, pp. 211-275.
Selden, pp. 56-130.
_Building Trades Pocketbook_, pp. 217-221, 237.
Griffith, pp. 86-104, 164-170.
[Footnote *: For general bibliography, see p. 4]
[Illustration: Fig. 264.
1 Lapped and Strapped
2 Fished
3 Fished and keyed
4 Spliced for compression
5 Spliced for tension
6 Spliced and Tabled
7 Spliced for cross strain
8 Dowelled butt
9 Toe-nailed
10 Draw-bolt
11 Plain butt
12 Glued and blocked
13 Hopper
14 Cross lap]
[Illustration: Fig. 265.
15 Middle lap
16 End lap
17 End lap with rabbet
18 Dovetail halving
19 Beveled halving
20 Notched
21 Checked
22 Cogged
23 Forked]
[Illustration: Fig. 266.
24 Rabbet
25 Dado
26 Dado and rabbet
27 Dado tongue and rabbet
28 Dovetail dado
29 Gain
30 Stub mortise and tenon
31 Thru mortise and tenon
32 Blind mortise and tenon
33 Mortise and tenon with rabbet
34 Wedged mortise and tenon
35 Wedged mortise and tenon
36 Fox tail tenon
37 Dovetail mortise and tenon]
[Illustration: Fig. 267.
38 Pinned mortise and tenon
39 Keyed mortise and tenon
40 Tusk tenon
41 Double mortise and tenon
42 Haunched mortise and tenon
43 Table haunching
44 Bare faced tenon
45 Housed mortise and tenon
46 Slip
47 Thru single dovetail
48 Thru multiple dovetail
49 Lap dovetail
50 Stopped lap dovetail
51 Blind dovetail]
[Illustration: Fig. 268.
52 Miter
53 Doweled miter
54 Spline miter
55 Slip feather miter
56 Slip dovetail miter
57 Double dovetail keyed
58 Ledge and miter
59 Stopped miter
60 Double tongue miter
61 Stretcher
62 Strut
63 Square thrust
64 Oblique thrust]
[Illustration: Fig. 269.
65 Brace
66 Housed brace
67 Oblique mortise and tenon
68 Bridle
69 Bird's mouth
70 Glue
71 Rabbeted
72 Matched
73 Beaded
74 Spline
75 Doweled]