Wood Joinery Techniques
The following are some of the most common wood joinery techniques.
This is one of the easiest joints to make. It consists of joining two pieces of wood at right angles and holding them
together with nails, screws, dowels, or biscuits (Fig. 1). A biscuit is a thin, flat, oval shaped disc of wood that is inserted
into a pocket hole that is made in the surface of the two pieces of wood that are being joined together. Biscuits and
dowels add strength to a joint. Glue should be used if using a dowel or biscuit. If the item is to be used indoors, then
regular carpentry glue can be used. If the item is to be used outdoors, then a waterproof carpentry glue should be used.
While this is not the strongest connection by itself, reinforcement can be added for strength.
Two common fasteners are corner braces and flat corner braces (Figs. 2 & 3). Scrap wood can also be used for
reinforcement (Fig. 4).
If your butt joint is a "T", it can be reinforced with a corner brace or a T-plate (Figs. 5 & 6).
Similar to the butt joint is the overlap joint, which is held in place with screws or glue (Fig. 7).
The butt joint is most often used when appearance is not a factor.
If appearance is a factor, a lap joint may be in order. This type of joint has a recess cut in one piece of wood - equal
in depth to the thickness of the crossmember - which will hold the other piece of wood (Fig. 8).
A half-lap has a slightly different technique. A recess is cut in both the crossmember and the sidemember, but only
half the thickness of the piece of wood. The appropriate glue should be used in all joints to add strength to the joint (Fig. 9).
A dado joint is a way of suspending shelves from its side supports. To make a dado joint, draw two parallel lines equal
to the thickness of the wood it is to engage. A cutaway will be made that is 1/3 the thickness of the wood (Fig. 10).
First cut on the lines, then chisel out the wood to the correct depth. This can be done with a router, a bench saw or
a radial arm saw.
A fancier type of dado - the stopped dado - cuts away only part of the wood and only part of the shelf is cut away.
Mark your guides for a stopped dado and chisel away the area to be recessed. Cut away on the connecting board for
an accurate fit (Fig. 11).
A rabbet joint is similar to a dado except that it is cut on the edge of a board. It's a fairly easy joint to construct and
is strong, especially when secured with nails, screws or glue (Fig. 12).
This is most commonly used when constructing inset backs for a cabinet or bookcase.
A miter joint joins two pieces of wood at right angles. A miter box is used to cut the wood. You may want to reinforce
the joint with nails (Fig. 13). This joinery technique is often used for molding, trims and picture frames. Mitering provides
an elegant "finish" look to many woodworking and carpentry projects.
Because the miter joint, even with the inclusion of nails, is not very strong, you may need more reinforcement. A
spline (which is basically the same thing as a biscuit) may be used to help join the joints and it's important to be accurate
while cutting these slots for a clean finish. The easiest way to make this cut is by using a router or a plate jointer. In
some cases, a table saw will do the job (Fig. 14).
Mortise and Tenon Joint:
A strong joint, used in projects where no other reinforcement will be used, is the mortise and tenon joint. This requires
a bit more skill but is worth the effort for a professional look.
There are two parts to the joint (Fig. 15) - the mortise and the tenon. The mortise is the recessed part of the joint, and
the tenon is the part of that fits into the mortise. There are many kinds of mortise and tenon joints in frame construction,
leg-and-rail construction, as well as other types of assembly. The blind or simple mortise and tenon is used in
leg-and-rail construction. If you want square corners, the cut is made on a mortiser or mortising attachment. The mortise should be
at least 5/16" from the outside face and at least 1/8" deeper than the tenon for clearance. The tenon should be about
one-half the thickness of the stock. If you want rounded ends, the rounded ends are cut on a router.
Finger Joint (also known as box joint):
This is a simplified version of dovetail joint. It is made by cutting matching notches and fingers in the two pieces to
be joined. This joint can be easily cut on a circular or radial-arm saw without special equipment. It is used in many
designs for both structural and appearance purposes.