The jig has a hooked support (4) which is attached to a screw adjustment (6) between two outer walls and which is adjusted to clip over the edge of the fitted board. The other end of the jig has a curved profile (2) over which the next board is slid and secured leaving the operator free to pin the board single handed. The side plates of the jig have an extension tag (3) alongside the hook to provide a spacing guide for the boards. The jigs are removed by a simple twist action after loosening the screw adjuster sufficiently.
