A butt joint is a wood joint in which the end of a piece of material is simply placed (or “butted”) against another piece. The butt joint is the simplest joint. An unreinforced butt joint is also the weakest joint, as it provides a limited surface area for gluing and lacks any mechanical interlocking to resist external forces.
Nonetheless, it generally provides sufficient strength in most cases, particularly when fasteners are used. The butt joint is widely used in many applications due to its simplicity, notably in rough carpentry and construction.
Methods
There are several types of butt joint based on the orientation of the pieces being joined. These include the T-butt, end-to-end butt, Miter butt and edge-to-edge butt.
The T-butt joint is a very simple joint to construct. Members are simply docked (cut off) at a right angle and at the required length. One member will be shorter than the finished size by the thickness of the adjacent member. For enclosed constructions, such as four-sided frames or boxes, the thickness of the two adjacent members must be taken into consideration. For example: when constructing a four-sided box made from 19 mm thick material that is to be of finished size 600 mm × 600 mm, two of the members will be docked at 600 mm and the other two will be docked at
Reinforced butt joints may require additional steps which are detailed below.
In solid timber, docking of members for a butt joint is usually a crosscut, so a crosscut saw is best for this job. When working with sheet goods, there is no distinction between crosscut and rip cut.
The joint members can be docked by any of the following methods:
Carcase butt joints
Crosscut saw
Circular saw and straightedge
Table saw
Frame butt joints
Crosscut backsaw
Miter saw
Table saw using a mitre gauge, crosscut sled, or sliding table attachment.
Reinforced butt joints
To overcome their inherent weakness, butt joints are usually reinforced by one of the following methods:
Nailed butt joint
This is the most common form of the butt joint in building construction. Members are brought together and a number of nails are driven in to hold them in place. The technique of skew-nailing is applied so that nails are not parallel to each other and so resist the pulling apart of the joint. This form of butt joint is rarely used in furniture making.
Used for: framing in building construction, such as platform framing Basic or temporary box/cabinet/frame making woodwork toys
Dowel reinforced butt joint
The dowel reinforced butt joint or simply dowel joint has been a very common method of reinforcing butt joints in furniture for years. They are common in both frame and carcase construction. Dowel joints are popular in chairs, cabinets, panels and tabletops. They are also used to assist with alignment during glue up.
The technique consists of cutting the members to size and then drilling a series of holes in the joint surface of each member. Holes are often drilled with the assistance of a dowelling jig which aids in accurate hole placement — accuracy is paramount in this technique to ensure members line up perfectly in the completed joint. The holes are drilled such that there are corresponding holes in each member into which short dowels are inserted with some glue. The joint is brought together and clamped until the glue has dried.
This produces a joint which is much stronger than a butt joint without reinforcement. The dowels offer some holding strength even after the glue has deteriorated. Over time, dowels may shrink and become loose. They take on an oval shape in section owing to the different rate at which wood moves with different orientations of the grain. Loose dowels allow the joint to flex, although it may not fall apart. This phenomenon is evident in creaking chairs and wobbling book cases. For this reason, dowel joints are not preferred for high-quality furniture.
Used for: Frame joinery (e.g. face frames, web frames, door frames, table legs to aprons, chair legs) Cabinet carcase construction (e.g. carcase sides to top and bottom, fixed shelving/partitions) Panel assembly (for alignment)