An alternative method for strengthening edge joints is one in which the projecting head of a countersunk steel screw enters a corresponding
hole and socket. The hole is bored to the diameter of the head, and the socket cut to receive the shank so that the head of the screw cuts its own path, while the bevel of the countersink pulls the edges together (136). For a tight fit the boards are first tried in position, and the top board tapped a little way home, as indicated by the arrow, to make sure everything lines up. It is then removed, the screw given a half turn, the edges glued, driven home and cramped/clamped. This joint is not now used to any extent, but may be useful for edge joints which have to be worked on before the glue is thoroughly set, and for dry jointing and secret fixings for panelling, wall fittings, etc.
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