Common Wood Joints for Woodworking
Posted by Lee Swindel
There are many types of wood joints used for boxes, chests, benches, cabinets, furniture construction, and a myriad of other possible projects. The type of joint selection will depend mainly on the strength and appearance desired. The quality of any woodworking project depends largely on the quality of the joint selected.
The joints mentioned are some of the most common ones used in the woodworking industry. Although there are only nine discussed, there are many variations of most that could be used. Unless you are a professional woodworker, the ones selected will suffice for most projects attempted.
The butt joint is the weakest and the simplest joint to make. It requires no additional cutting. It only requires the end grain of one board to be joined with the face or edge of another board. Since this joint is so weak, it is rarely used without some other way to strengthen it. Some of the most common joint strengthening methods, in addition to glue, include using staples, nails, and screws. Additional methods used to give greater strength include the use of corner glue blocks, dowel pins, and metal plates attached with screws. Since dowel pins add much greater strength and are not visible, they are commonly used to join rails to legs in the construction of tables and chairs.
The edge joint is also a very weak joint, similar to the butt joint, but in this case the edges of the wood are joined together. This type of joint is used to expand the board width for making table or desk tops. It is typically strengthened by first jointing the edges, and then using dowel pins and glue. If the joint is not going to incur much stress, then a spline can be used to strengthen the joint instead of dowel pins. This would require cutting a groove in each of the edges and gluing a wooden spline into them. To prevent cupping, alternate the end grain pattern of each board.
The miter joint is made by joining two boards together at the corner to form a 90 degree angle. This is accomplished by cutting the end of each board to a 45 degree angle. The miter can be cut using a table saw or a radial arm saw. But for more accuracy a power miter saw should be used. Miter joints eliminate the exposure of end grain, and are primarily for framing, such as for picture frames. Miter joints are also very weak, and are commonly strengthened by adding a spline or a biscuit. A blind spline is usually preferred because it is concealed within the joint. This is accomplished by cutting a groove part way in the adjoining members, and then a wood spline is glued into the joint. The biscuit is a small, thin oval shaped piece of wood that is inserted and glued into the joint. A biscuit cutter is used to cut grooves for the biscuit.
|End Lap Joint
The end lap joint is another simple joint that can easily be made using a dado blade on a table saw or a radial arm saw. This can be accomplished by removing the width and half the depth of each board and joining them at a 90 degree angle. This joint is primarily used to frame the corners of projects. Other variations of the end lap joint include the cross lap joint, the edge cross lap joint and the middle T lap joint. Each of these joints are shaped by the same technique, but are used for different purposes. These joints can be strengthened with metal fasteners. In many cases, unless the joints will be under a great deal of stress, no additional strengthening is required.
A rabbet joint is made by cutting a dado on the end of one board and fitting another board into the dado. The dado can be made by using a dado cutter on a table saw or a radial arm saw. The width of cut should be equal to the thickness of the adjoining board and the depth of cut should be one half its thickness. This joint is typically strengthened using staples, nails, or wood screws. The most common uses of a rabbet joint are for making drawers and boxes. When making boxes, both dados and grooves are usually required.
A dado joint is made by cutting a dado, across grain, where needed other than on the end of the board. It is typically made by using a dado cutter attached to a table saw or a radial arm saw. The width of cut is equal to the thickness of the board to be inserted into the dado. The depth of cut is one half the thickness of the board being cut. Dado joints are commonly found in bookcases or cabinets, or wherever shelving supports are required. This type of shelving is permanent, so trim is usually attached to the front of bookcase or cabinet to improve its appearance.
|Lap Dovetail Joint
The Lap dovetail joint requires the use of a router with a dovetail bit, a dovetail jig and a template. The ends of two boards are held in place using the dovetail jig. The router cuts the dovetail joints in both pieces of wood. The template will determine the exact placement of each dovetail that is cut. The dovetails are tapered to provide a very strong joint by slipping the sides onto the drawer front. These joints are typically used for expensive drawer construction, where a solid drawer front is required and only the sides of the joint are visible. Also, dovetail joints can be made manually, by drawing the shape and size of each dovetail onto the wood, and then cutting them with a back saw. This is a laborious process and the joint precision is usually not as accurate compared to the router/jig method. A couple of variations to the lap dovetail joint include the through dovetail joint, where the sides and fronts of the joint are visible. The blind dovetail joint is just the opposite, where the tails and pins of the joint are completely concealed. Expensive trays, boxes and small chests are usually made with this type of joint. Dovetail joints are considered one of the strongest joints used in for woodworking, and when glued, no additional strengtheners are required.
The finger joint is similar to the dovetail joint, but is much simpler to make. No router or dovetail jigs are required. Also, the finger joint is cut straight rather than tapered like the dovetail joint. It can be cut using a dado cutter on a table saw or a radial arm saw. The fingers should be cut to uniform sizes on each adjoining board. They should also be offset so the two boards will properly fit together. The depth of cut should be equal to the thickness of the boards. This joint is typically used for box construction. It is also used for drawer construction, where a solid drawer front is attached to the box face so that only the finger joints are exposed on the side of the drawer. This is a strong joint, and nothing more than glue is usually required for strength.
|Blind Mortise and Tenon Joint
The blind mortise and tenon is a very strong joint. Its primary use is for leg and rail construction. The tenon is cut on the ends of the rails, and the thickness should typically be cut equal to ½" the thickness of the stock, for stock thicknesses up to one inch. For stock thicknesses over one inch, the tenon thickness can be proportionately less than the one half the percentage previously suggested. Also, it is recommended that the tenon be ¾" long. The tenon can be cut using a dado cutter on a table saw or a radial arm saw. The mortise is cut into the legs using a mortise machine. The mortise should be cut to the same dimensions as the tenon, except that the depth of the mortise should be 1/8" deeper than the tenon length. In most cases just gluing and clamping will suffice. But if additional strength is needed, a wooden pin can be used. The blind mortise and tenon joint is considered the most common, but other variations such as the barefaced, open, through, and angled are also used, depending on the situation or desire.
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- provenwoodworking .com/
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- Mortise and Tenon Dimensions