In manufacturing, an end-joint is the point where two pieces of material are fastened to one another using adhesive or mechanical fasteners. Woodworkers and cabinet makers often use this term to refer to the intersection of two pieces of lumber or sheet goods. For example, when two pieces of lumber are glued end-to-end to form a single unit, the point where the two pieces meet is considered the end-joint.
Woodworkers use three basic techniques to join wood together and form an end-joint. The simplest technique involves butting the two pieces of wood together. While this method is quick and easy, it produces a weak end-joint that is unable to withstand heavy loads. Unless some form of additional reinforcement is used, butted end-joints should only be used on low-stress applications.
Overlapping end-joints, or scarf joints, offer a more secure method of joining wood. This technique produces a less noticeable joint, making it a viable option for wood furniture and cabinetry. To form an overlapping end-joint, workers shave the end of the wood to form a diagonal, then fit the two pieces together to form one smooth, continuous piece. Scarf joints offer better strength and durability than butt joints, but also require more skill.
Finger joints offer the highest level of strength and security for joining two pieces of wood. To use this technique, workers cut a pattern of teeth in the end of each board, then interlock these teeth together for a secure hold. This technique is often used on high-end cabinetry and furniture.
Many woodworkers use glue or adhesives to hold wood together at the end-joint. In some cases, additional reinforcement may be needed to improve the strength of the joint. Workers may cut hidden holes in each piece of wood, then use thin wooden poles, or dowels, to join the pieces together. Others use round wooden cutouts, or biscuits, which fit into a pocket cut into each unit of lumber. Screws, bolts, and other fasteners also offer an effective method of securing an end-joint.
The term “end-joint” is also widely used to refer to the point where adjacent pieces of flooring or drywall meet during installation. For example, the boards on a hardwood floor are fastened to the subfloor, not necessarily to one another. During installation, workers strive to stagger the end-joints on these boards to produce a more stable floor surface. The same is true for drywall installers, who stagger the end-joints on sheets of drywall to increase stability and appearance.