Originally Posted by MARTINSR
That is a great idea! If you butt it perfectly you don't need it, but if you can't, a long seam like that is pretty hard to make perfect, you can put the copper backing, BRILLIANT!
Martin, doing a long seam such as a quarter skin doesn't just want to butt up perfectly, my one year old daughter can scribe a line and get a good butt. The gaps are the least to worry about if you can weld. The issue is having it sit flush. We're talking a long seam that wants to sag. As far as copper, I don't really use it anymore cause it brings the molt back too far. If you ever did a hole start to finish with it and grind the backside it will have an inward dimple. So I use them to start a big hole by one or two tacks bridged, then it's coming off, or, I will use it to fill a crack on the edge of something that will otherwise want to burn away.
I just want to use backing for a few tacks to keep the darn thing flush. once it's held up I will do away with it and finish it off.