What Is Joinery?
Joinery is the method by which different pieces of wood are attached, and is often an indication of the quality of a piece of furniture. The manner in which seperate members of a chair, table or chest are attached to each other reflects strength of construction as well as appearance. An article of furniture assembled with simple butt joints is less likely to hold up under years of use than one that uses mitered, dowel or tongue and groove joints. While most methods of joinery present an almost seamless method of construction, some joints such as dovetails are actually designed as a decorative feature of the piece. Listed below are the most common types of joinery used in furniture construction.
A butt joint is a simple method of connecting two pieces of wood with the square end of one piece being placed against the side of another. The two pieces form a right angle and are joined by a nail, screws or a dowel.
Cross Lapped Joint
In a cross lapped joint, a rectangular section is cut out of each of two pieces of wood that are to be joined. The recess is cut from each piece at the point where they intersect. The recessed surfaces interlock and must be equal in depth so that when the two pieces are joined they are flush.
A dado joint connects two pieces of wood by cutting a groove in one piece of wood which is equal to the width of the second piece. The second piece is then inserted into the groove.
A dovetail joint connects two pieces of wood by flaring the end of one piece to conform to the shape which is cut out of the second piece. If the end of the flared piece does not extend all the way through the second piece it is an invisible joint and called a stopped or lapped dovetail joint. This method is commonly used on drawers and cabinets. A dovetail joint can also be used to join several pieces together, with each piece haveing a flared end and a cut end.
In a doweled joint, small holes are cut in each of two pieces of wood at equal distances. They are then joined by inserting small, round pegs into the holes of each piece so that they line up with the piece to be joined. The pieces are then glued.
In a miter joint, two pieces of wood are cut at a forty-five degree angle and the two beveled edges are placed end to end. They are usually connected by glue, nails or screws.
Mortise and Tenon
In this method of joinery, one piece is called the mortise and the other is the tenon. The mortise is a shaped recess, and the tenon is a carved projection, usually rectangular. The tenon is inserted into the mortise in the same way a peg is inserted into a hole. The two pieces are generally secured by drilling a hole through the two pieces and inserting a dowel.
In a rabbeted or rebated joint, a groove is cut into one piece and a shaped protrusion is cut on the second piece. The protrusion of one fits into the groove of the other. The groove must be cut to match the "tongue". The rabbet joint is frequently used in cabinetwork, although finer pieces generally feature a mitered rabbet joint, which produces a neater appearance.
In a scarf joint two pieces of wood are joined by two metal plates with holes. The two pieces of wood are placed end to end and the plates are placed on each piece of wood. The plates are then attached to the wood by nails or screws.
In a spline joint grooves are cut in the ends of each piece of wood so that they line up. A small strip of wood called a spline is inserted into each groove to join the two pieces of wood.
Tongue and Groove
In a tongue and groove joint, two pieces are joined by cutting an edge or shape on one piece of wood which fits into a groove cut in the other. The tongue and the groove must be equally cut.
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