Wood joinery, in its various forms, has been used to build, craft, construct, and to secure our human projects for thousands of years. Accordingly, there are many techniques for wood joinery circulating the industry and although they all do essentially the same thing, each method has an individual focus and, consequently, produces a different kind of joint.
To take a small step backward, wood joinery is the binding of two separate workpieces. Each piece must be of equal thickness and must planed flat along their adjoining edges. The goal of joinery is to produce an angle or to elongate/extend an existing workpiece. Various techniques are employed to create joints that are everything from durable to delicate and invisible to aesthetically pronounced. As such, the array of methods a woodworker can apply to produce a wood joint is staggering; while extensive, though, the list of joinery methods is also comprehensive rendering wood joinery a craft that appeals to woodworkers of every skill level. The below list, then, reflects the most common techniques for binding two pieces of wood.
Common Wood Joinery Methods:
A biscuit joint is most commonly used to join workpieces end-to-end to create one larger panel out of several smaller panels (i.e. tabletop making). In a nutshell, a crescent-shaped slot is cut into exact opposite points on two adjoining workpieces. The slots are glued and a “biscuit” or oval-shaped piece of dried and compressed wood shavings is inserted into one slot for each pair of slots. The slots are brought together (with the biscuit between them) and clamped into position. As the glue sets, the biscuit expands with the moisture of the glue and reinforces the joint. After assembled the joint is strong and, effectively, invisible.
Frequently used in construction, a butt joint, while not extremely attractive, is a very simple, very common wood joint. This method involves simply binding two pieces of wood (at their edge, of course) to produce a right angle. This joint requires reinforcement.
– Mitered Butt Joint:
For a bit of variation in your run-of-the-mill butt joints, one will also encounter a mitered butt joint. Similarly, this technique binds two workpieces to make a right angle, this technique, however, binds them with mitered edges (or, edges that have been cut at a 45-degree angle). While less durable than some joints, this detail produces a more attractive butt joint than its basic butt counterpart.
A dado joint involves carving a slot into the surface (not the edge) of a workpiece and affixing the edge of another workpiece into that slot. This is a strong joint that binds your workpieces perpendicularly. Dado joints are often used to create shelving (i.e. for bookshelves).
Posited to predate written history, a dovetail joint is a very strong, very resistant wood joint that is both effective and attractive. This joint is formed by cutting a series of trapezoidal “pins” into the edge of one workpiece and a series of complimentary “tails” into a corresponding workpiece. The pins (tabs) interlock into the similarly (yet also oppositely) cut tails (slots) to form a flush, tight bond. The angle of slope that forms the pins and tails (or, interlocking trapezoidal segments) may vary. To avoid gaps or movement between segments, dovetails must be cut with careful accuracy. After gluing, these joints require no additional reinforcement and, though frequently used in the fabrication of drawers and boxes, dovetails are used in numerous woodworking applications.
– Through Dovetail Joint:
For its aesthetic qualities and also for its uncommon strength, a through dovetail is probably the most frequently used dovetail joint. It is, more or less, the standard dovetail joint in which the end-grain of both workpieces is visible after assembly. This is often regarded as a very beautiful joint and emphasizes the skill of the crafter behind it.
– Half-Blind Dovetail Joint:
Like the standard dovetail, this joint involves interlocking pins and tails. As the name would imply, though, after this joint is assembled, the end grain of one workpiece (on one side, usually the front) is hidden by the other workpiece. This allows the mechanics of the joint to be hidden from certain angles of sight and visible from others.
– Double-Blind or Full-Blind Dovetail Joint:
Although this joint also features interlocking pins and tails, the construction of the joint hides these segments altogether. In other words, the mechanics of the completed joint are invisible. This method is employed when the strength of the dovetail is required but the visibility of the joint is not. To form this joint, pins and tails are carved but they are not cut entirely through the workpiece – they stop short leaving the one surface of each workpiece intact and untouched. This allows the pins and tails to interlock underneath a of section uncut material.
– Sliding Dovetail Joint:
Like a dado joint, a sliding dovetail joint binds two workpieces where the edge of one workpiece joins at an intersection to the surface of another workpiece. To form this joint, a pin (or tab) is cut onto the entire edge of one workpiece. A tail, or slot, is then carved into the length of the surface of the adjoining workpiece. The pin is then slid and fitted into the slot to form a tight, strong joint. This method is employed in a huge number of carpentry applications.
Mortise and Tenon Joint:
A mortise and tenon joint is similar to a dovetail joint in that it involves joining two workpieces together at an angle where one workpiece has a “mortise” or slot and the other has a “tenon” or a tab. The mortise and tenon then interlock to bind the joint. These tabs and slots are ordinarily rectangular in shape.
Like biscuit joinery, a tongue-and-groove joint is primarily used to join workpieces end-to-end. To form this joint, a tongue is carved along the entire edge of one workpiece and a groove is similarly cut into the edge of its adjoining piece. The tongue is a tab-like protrusion that fits squarely into the groove which is, of course, a slot-like formation. This technique is often used in furniture production, flooring and paneling, and, although not typically glued, produces a very durable joint. Also like a biscuit joint, this bond is hidden upon assembly.
A rabbet joint is very commonly used in drawers, cabinets and other carpentry applications. To form this joint, a “rabbet,” or a step-like groove, is carved along the entire edge of one workpiece. The edge of another workpiece is then placed onto this groove to form a right angle. Accordingly, the depth of the rabbet is determined and cut based on the thickness of its companion piece. Upon assembly, this joint binds the long-grain of one workpiece to the end-grain of the other. Because this typically doesn’t glue well, the joint is often reinforced with screws, nails, or dowels.
– Double-Rabbet Joint:
A double-rabbet joint involves cutting a rabbet along the length of each edge being joined. This creates a more attractive joint and because the gluing surface area is greater, a stronger joint as well. The second rabbet also ensures the squareness or accuracy of the angle produced.
– Mitered Rabbet Joint:
Like the double-rabbet, a mitered rabbet joint involves cutting both edges being joined. This method, however, also incorporates mitered edges. To produce this joint, a rabbet is cut into each adjoining edge and the top step (shoulder) of each rabbet is mitered at 45-degrees. Although slightly more difficult to produce, this joint is stronger and commonly regarded as more attractive.