Figure 2. Lap joints.
illustrated in figure 2, B. If one end of a lap joint joins
the other in the center, as shown in figure 2, C, the joint
is known as a middle lap joint.
2-11. Lap joints are used by the carpenter in framing
timbers for sills and girders. Cabinetmakers use lap joints
Figure 4. Grooved joints.
for connecting crossrails to the side of cabinets and for
many other types of frames.
plain dado in regard to the horizontal member, which is
2-12. Grooved joints. Grooved joints are those which
rabbeted to fit the dado. To counteract strain, a dado
have a groove, or recess, cut into one member, either
joint can be dovetailed, as shown in figure 3, D.
with the grain or across the grain, into which the edge or
Dovetailed dado joints can be constructed in the blind, or
end of the other member is fitted. The grooved joint is
stopped, dado style.
a familiar joint to the cabinetmaker and has many
2-14. Grooved joints have the groove, or plow as it is
sometimes called, running with the grain of the wood.
2-13. Dado joints are actually grooved joints with the
They are used extensively in panel construction. Figure 4
groove running across the grain of the wood. They are
illustrates three methods in which a member can be
inserted and fitted into a groove. Grooved joints can be
The dado is a housing, or groove, cut into one member
plain or cut with a rabbet or tongue and can be joined
with the other member fitting into this groove. A plain
dado is one which extends completely across the board.
either glue or nails. However, when a panel is inserted
and surrounded by a frame, the panel is made to fit snug
fig. 3, A.) When the groove, or dado, is not extended
but is not glued or nailed. This allows the panel to swell
completely across, as illustrated in figure 3, B, it is known
or shrink without breaking the frame. Grooved joints
as a stopped, or blind, dado. A shouldered dado (see
can be cut with the circular saw, using a dado head.
fig. 3, C) differs from the
2-15. Miter joints. Miter joints are diagonal joints used
extensively for frames and moldings. Shown in figure 5,
A, is a plain miter joint, which can be fastened with glue,
dowels, wood screws, nails, or corrugated fasteners.
2-16. The mitered half lap joint (see fig. 5, B) is
similar to the end lap joint and can be mitered to any
desired angle. This type of joint can be fastened with,
glue, nails, wood screws, or a combination of glue and
metal fasteners. The splined miter is a method used to
Figure 5. Miter joints.
Figure 3. Dado joints.