Modified National Super

A Modified National super comprises two outer walls, two inner walls, two top locking bars and two bottom locking bars. The outer walls each have two long grooves and 4 cut out slots, the inner walls are plain and slightly smaller. Also included are frame runners and/or a pair of castellated spacers and all necessary nails.

Start by attaching a frame runner to each of the inner walls. Attach the runner to one edge of the inner wall using the brass escutcheon pins ensuring that the runner is spaced equally from each end of the side wall.  If assembling a Thornes standard super, ensure the runners are attached to the same edge of the inner wall that has a sawcut along its length. Attach the runner so that it is on the face of the inner wall furthest from the saw cut.   Inner wall showing the position of the frame runner

If assembling a Budget super, there are no saw cuts in the inner wall and frame runners are not used. In this case the castellated spacers are nailed centrally on one side of the inner walls, using brass escutcheon pins. The castellated spacer cut-outs must project above the inner wall by ¼”.

Inner wall showing position of castellated spacers

Mark the outer wall 7/16” down, adjacent to the long groove.Marking position of top of inner wall on side wall

Apply glue to the grooves in the outer walls and then push the inner boards into the groove, ensuring top of runner coincides with mark. If assembling a Budget super, the top of castellated spacers must be flush with the top of box.Assembly showing the position of the inner walls


Apply glue to the inner faces of the locking bars and then push them into the slots, bevelled type at the bottom.


Assembly showing where the locking bars fitNail through outer walls into inner walls using 2” nails. Nail locking bars into position using 2” nails. Nail locking bars from inside 3/16” down from runner, using 1 1/2” nails. Showing nail positions for the completed assembly

If assembling a Thornes standard super, the castellated spacers are fitted by pushing into the sawcuts along the top edge of the inner walls.

Printable version of these national super assembly instructions