Today I welded into place the front steel sections of the right fuselage side stringers and then brazed the supports for the aluminium rear sections to the fuselage cross members. The process I used for positioning all the supports was to clamp a length of steel 5/8" tubing acting as a dummy stringer to the fuselage and then position the mounts which are semicircular sections of the same tubing between the cross members and the dummy stringer. Because, as it's the same diameter, the dummy stringer won't sit down into the mounts it is then possible to apply flux and then braze the mount to the cross member without having to get the dummy stringer too hot or accidentally brazing it into place as well. The 2nd picture shows the way the braze metal wicks into the space creating a neat and strong joint. The mount is offset from the cross member to allow space to pop-rivet the aluminium stringer to it from the inside.
