DIY Aluminum Radiator Repair

I have tried the aluminum rods at Harbor Freight, which are a copy of the Muggy Weld. They never stuck for me. One attempt was aluminum sheet roof, the other a cast aluminum convertible frame (my 1964 Valiant). I abraded to shiny aluminum and tried fast, rubbing the rod as youtubes show. Perhaps it works better on aluminum extrusions, like the demos.