Generated from an approved conversation, then reviewed by participants. Corrections stay visible.
A good joint increases contact area, resists movement in the directions a load will push, and lets the wood fibers carry force. Glue then bonds a broad, well-fitting surface rather than doing all the structural work alone.
Building the idea, one step at a time
Wood is stronger along the grain than across it. Joint design works with that direction so force travels through long fibers instead of splitting short ones apart.
A mortise-and-tenon or half-lap adds mechanical interlock. The shoulders resist racking, while the fitted surfaces spread force across a larger area.
Glue is strongest as a thin film between clean, close surfaces. Gaps turn that film into a brittle filler and reduce how much of the joint truly participates.
The right joint depends on the load: pulling, twisting, or sideways racking. Naming that load is usually the best first step in a repair.