A spline bridges the gap between two boards, fitting tightly into a dado or groove cut into the mating edges. It dramatically increases the glue surface area and aligns the faces perfectly during assembly. Splines are commonly used in edge-to-edge panel glue-ups, mitered picture frames, and complex angled joints where traditional fasteners would fail or look ugly.
Heard on the job
I added a contrasting walnut spline to the mitered corners of the box for extra strength.
Also heard as
- slip tenon
- loose tenon
Do not mix it up with
- Biscuit: A biscuit is a specific oval-shaped manufactured spline, while a true spline is usually a continuous strip cut from solid wood.