Cutting Splined Joints

Splines are an effective way to add strength to a mitre joint.

The raw timber frame is cut with mitred corners, glued and allowed to dry under pressure with no pins or other hardware used.

Once the glue is cured and the frame is solid, slots are cut perpendicular to the mitre. Timber 'biscuits' planed to the thickness of the slot are then glued into place with the grain of the biscuit travelling across the mitre, rather than with it.

This crossing of the grain is essential. Cracking and splitting in timber always occurs in the direction of the grain (think of an axe splitting logs), so to add strength to any joint or structure, the grain should be crossed. In the manufacture of ply sheeting grain direction is alternated as layers are lamintated together to make a rigid board.

As a rule splines do not constitute sophisticated locking joints, but we have developed our own swallow-tail splines, that as well as preventing cracking from downward pressure on the mitre, can help prevent the joint opening from outward pressure.

Heavily patterned iroko frame with contrasting long 2 mm maple splines.

Walnut frame, grain travelling around the perimeter with 3 mm dark walnut splines.

Contrasting Splines

Other Materials

Image: Hormazd Narielwall for Lucy Williams. Bespoke. Polished brass splines in maple

Box Joints