The basics of wood joints

Even solidly built utility furniture seldom lasts for a lifetime because it is constantly being used. Any repair work on wooden furniture begins with the stabilising of joints, frames and stands.

Instructions

Even solidly built utility furniture seldom lasts for a lifetime because it is constantly being used. Any repair work on wooden furniture begins with the stabilising of joints, frames and stands.

There are three different types of wood joints for connecting workpiece parts together: material closure (e.g. glued), force closure (e.g. bolted, nailed, wedged) and form closure (e.g. slotted, dowelled, pinned).

Wood works – even in board form. This must be taken into consideration for all joints, in particular those made of solid wood. Wooden parts can be joined together in a detachable or undetachable manner. Detachable joints use appropriate fittings to hold the individual elements together. Undetachable joints are always made with an adhesive and can – as long as they do not become loose of their own accord over time – only be undone by being destroyed.

The most common joints are form closure joints. Here is a selection:

Blunt, dowelled joints are very commonly used in furniture manufacture. These joints are made by drilling in dowels and are extremely durable. However, they are difficult to produce – as is the case with the extremely sturdy corner joints with biscuit dowels. This is why corners are also often joined together using tongue and groove joints.

The overlap is the simplest corner joint used in frame making. It is made by cutting out half of the wood thickness from each part of the workpieces that are to be joined; the workpieces are then glued together. However, this joint is not particularly resilient. For this reason, they should be additionally secured using screws or pins.

The mortise and tenon joint is particularly suitable for producing window and furniture frames. The upright frame parts are normally given slots, the horizontal parts are given tenons. Double tenons are common in thick wooden frames.

Dovetailing is multiple interlocking of straight or wedge-shaped tenons, also called dovetails. This type of joint is used for solid wood because the joined parts can expand or shrink unhindered without losing their shape. The dovetail joint is also a form of visual ornamentation.