When all interior leads are in place, the top edge came is cut to butt against the vertical side edge, using a small piece of lead the same size to act as a gauge. These edge cames should butt up to the came ends in the interior.
Place a narrow strip of wood against the top outside came and hold it in place with horseshoe nails. Check with a square or by measuring to be sure the just placed came is at right angles to the left side of the panel. Do the same with the other side.
If adjustment is necessary, firmly tap the wood batten with the hammer end of your lead knife to get it into position. Place nails to hold the cames in position and get ready to solder.