Wood joinery is an integral part of woodworking and has been practiced for thousands of years. From furniture design to building doors and windows, to decorative purposes; everything involves wood joinery. In some types of wood joinery, modern tools can be used to potentially make their creation slightly more achievable, but most require great precision; demanding expert artistic skills.
With the help of tool innovation and creative minds, more and more types of wood joints have been established throughout the years. The first-ever recordings of the use of wood joinery come from the First Dynasty in Egypt! We have come a long way since then, and today we’re going to explore what humanity has come up with in the past few thousand years.
Wood joinery at its core is the union of two wooden pieces to create a new resultant structure. The wooden pieces may include different types of wood such as lumber and timber. The two significant woodworking tools we use include a jig (this ensures precision in cuts made by cutting tools) and a fence, which is an edge that helps in bracing the sliced material.
Different types of wood joinery have varying degrees of strength, whereas others are designed to be visibly appealing. Some will be joined into corners, others will be joined in the center field of a workpiece, and others may be joined edge to edge (like in-floor paneling).
Before you attempt to primary woodworking skills, make sure you have a sound understanding of all the different types of joints. After all, the quality and durability of the end products are highly dependent on how firmly the pieces are joined together. Let’s have a look at these types:
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The Butt Joint
The butt joint is the most common type of wood joint and is probably the first one that you come across while studying woodwork. They are often used to install trims and baseboards, or wall framing at construction sites. They are commonly seen on window and door trim where vertical pieces of trim are butted into the horizontal ones at the top of the window or door or into a horizontal window sill. So, pretty much everywhere.
In a typical butt joint, two pieces of wood will be joined end to end at a 90-degree angle (also referred to as a corner joint). They will be reinforced using glue, as well as nails, metal clips, screws, or dowels. Since the butt joint is so reliant on extraneous additions for strength, they are one of the weaker kinds of joints. However, they are the simplest to fashion and require next to no skill.
If you wish to ensure firm butt joints, using a hand saw or a circular saw may not create a perfectly straight or angled edge. Ideally, a chop saw should be used for cleaner accuracy.
The Miter Joint
Miter joints are frequently used in picture frames and some styles of doorway casing. In the case of picture frames, they are used at all four corners, while for some doorway casing styles, they appear in only the 2 upper corners.
A miter joint is quite similar to a butt joint as it attaches two boards at their ends to create a corner. However, the distinction lies in how those ends fit each other. As opposed to meeting at a 90-degree angle as in the case of a butt joint, the workpieces are cut at a 45-degree angle to join at 90-degrees.
Another difference between the butt joint and the miter joint is that the miter joint is used when a corner needs to look visibly appealing. Once the boards are joined, no end grains or joint will be visible. Miter joints aren’t designed to be particularly strong or weight-bearing. They are used for purposes of beauty and neatness.
To make a miter joint, sing a miter saw helps to cut precise angles, helps ensure tighter miter joints, leaving no gaps in between the boards. Also, the piece you’re cutting must be held firmly against the saw to avoid any movements during the cut. Once a proper angled cut is established, it should be joined with glue and clamped together until the glue is completely dry. It may also be reinforced with nails or dowels.
The Tongue and Groove Joint
Tongue and groove joints are generally used to position objects that are laid flat, such as floorboards or luxurious looking ceilings. Those who are aware of a laminate or a floating wood floor would probably have some idea about how the tongue and groove joint works. Typically, the tongue and groove joint is much stronger than the miter joint and butt joint.
This type of wood joint is different than the two previously discussed, in that it attaches two boards together along their edges, not end to end in a corner. Each board has a groove cut along one edge and a deep, thin ridge on its opposite edge. The edge of one board is then notched into a groove, whereas the edge of the attaching board is extended in the form of a thin tongue that fixes the groove.
To ensure that the tongue is inserted into the groove at an angle, both the tongue and the groove are slightly twisted into a curve-like shape. Finally, once the boards are joined and laid down, they get locked and cannot be detached unless any one of them is held up at a specific angle. They are sometimes reinforced with glue, but this is not entirely necessary since the joint itself is reinforced by the entire surface tension of the workpiece.
You may opt to craft tongues and grooves along the edges of the board by yourself using a shaper and a saw in DIY hardwood flooring and beadboard. However, most of them already have tongues and grooves cut and all you need to do is fix them together at the time of installation.
Make sure to fit the tongue and groove boards tightly against each other. You can take the help of a rubber mallet as you attach them. In the case of hardwood flooring, a hardwood flooring nailer is a perfect tool that joins the boards precisely together, while accurately inserting the nails.
Source: The RTA Store
The Mortise and Tenon Joint
Mortise and tenon joints are the earliest forms of joints found in ancient structures that date back to thousands of years. They have been in use since the early times of woodworking and are most widely used today. These joints are most commonly used in furniture design. They can be used anywhere from chairs, to tables, to bed frames, you name it!
In a mortise and tenon joint, one end of a wooden piece is tapered and inserted into the carved space of another wooden piece. The carved space is called mortise and the piece that fits into space is called tenon. This joint is very similar to the tongue and groove joint, only it has the capability of being joined into a corner, and the grooves and tongues themselves are much shorter; whereas the tongue and groove joint extends the full length of the workpiece.
Although modern tools have made the practice easier, the quality of the mortise and tenon joint still depends on the skill of the craftsman. For instance, excess wood can be cut away using a router, leaving a square or rectangular shaped space, and a drill press or a plunge router can be used to cut out the mortise. Yet, a skilled craftsman would make sure that the mortise socket is precisely cut into slightly a deeper space than the tenon length. This helps disperse the glue that’s used to attach the wooden pieces to each other.
The Dowel Joint
The dowel joint is quite similar to a mortise and tenon joint in that it too creates joint by filling a socket. What’s distinguishes it from mortise and tenon joint, is the addition of a dowel which is a cylindrically shaped separate entity. Sockets are drilled into both of the ends of workpieces, then the dowel is place between them and glued. Additionally, a dowel can be used to strengthen all other types of joints.
Dowel joints are most commonly used in wood-crafted projects in which other joint types wouldn’t effectively work. They’re mostly preferred for items on which visible screws and nails don’t look pleasing, such as bookshelves, luxurious cabinets, custom stairways. When the dowels contrast with wood, they often present a rustic appearance (for instance, the use of walnut dowels in oak construction).
Traditionally, dowels were crafted by hand, but contemporary dowels are already molded into a cylindrical shapes, and sockets are carved using power drills. To achieve the perfect joint, apply glue and fasten the two pieces together let them dry overnight before drilling the socket. In this way, when you hammer the dowel, the wooden pieces won’t move, resulting in a compact joint in the end.
The Lap Joint
As the name suggests, lap joints are characterized by an overlap of two pieces of wooden. They’re considered ideal for structural framing of houses or to establish support to weaker wooden joints that may otherwise split apart. Lap joints are further categorized into two types, namely the full lap joint and the notched lap joint:
The Full Lap Joint
Full lap joints are those in which a wooden piece overlaps another and attached together using a nail or a screw. They are most commonly used to support the structure of a house, but they are also used to strengthen other wooden pieces. For instance, vertical pickets in a gate can be joined together by lapping a diagonal piece of wood horizontally on top of them.
The Notched Lap Joint
A notched lap joint is also involves overlapping of two wooden pieces but the pieces are notched before being attached together at the notched segments. The notched lap joint adds additional strength to the frame as they are doubly reinforced. However, to prevent any confusion about which side to cut (top or bottom) lay out the pieces and mark both surfaces that are to be cut at the same time.
Source: Bob Vila
The Dovetail Joint
The dovetail joint is the most aesthetically appealing and coveted joint in cabinet and furniture making. The joint is incredibly strong and is highly dependent on the craftsman’s skills for accurate measuring. Once locked into place, there aren’t many things that could separate the dovetail joint.
To attach separate boards to each other, right-angled notches are cut in the ends of both the workpieces such that they are tightly placed into each other like puzzle pieces. One or more notches are cut in one wooden piece and the corresponding ‘tails’ are cut in the other piece and both are joined together. They are sometimes reinforced with glue, but the design of the joint makes them resilient all on their own.
Since the notches are firmly positioned, the chances of loosening are very low. Therefore, the finished product has the potential to carry heavy loads. It is commonly used in creating the sides of drawers and wooden lids or boxes.
Dovetails today are usually cut using a router. So, make sure you have one, and if you wish to make a lot of dovetail joints, you better buy a dovetail jig for the router. Dovetail jigs give the flexibility your router needs to cut notches and tails that can precisely fix together.
The Dado Joint
Dado joint is one of the simplest forms of joints you’ll get to see in woodwork. It’s quite similar to the tongue and groove joint since it involves cutting of notch in a wooden piece where another piece can fit. However, the end of one piece slides into the center field of another piece.
The dado channel is a three-sided channel of any length (most commonly the length of a shelf) which will be received by a panel of wood in a corresponding size. They can be reinforced by glue (if the shelf won’t be carrying much weight) dowels, screws, or nails.
Helping to fix two pieces of plywood together, dado joint is often used to locate partitions inside cabinets and to put together the backs and sides of dressers and cabinets with the top. It is also used in bookcase units to support the shelves.
The Rabbet Joint
As opposed to the dado joint, the rabbet joint involves cutting a notch at the edge of the boards, rather than at the center. The boards are joined by cutting the thickness of one board to position another board. Each edge will be shaped like a set of two stairs and will be glued with one of the steps overlapping the other. Since this joint is found on a corner, it must be reinforced with glue coupled with either screws or nails.
Rabbet joint is used to fix backboards onto the backside of pieces. It is also commonly used to connect cabinets or creating boxes in which edges need to fit firmly. It is not particularly weight-bearing, and it meant more for framing.