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!
some people like sheetmetal butted tight (me included) so that leaves out those butt clamps.Without a strip you cant screw it all together,hold it in place and remove it for more trimming. Screw holes will all line up when you put it all back together showing you its in exactly the same spot every time.Now I've seen guys fighting to hold a panel in place with one hand and tack it on with the other and it gets messy by the time its ready for actual welding...Thats one big advantage to using a flanged joint (something for the screws to bite into) ...The problems with using a steel strip is its gets welded in with the rest of the seam,PLUS the top will act like a cup and hold water and moisture ,rusting it out well before its time.Seam sealer can help but your totally relieing on the sealer so a steel strip is out...a copper strip cant be welded so its removable after welding,it helps with warpage,and really does a better looking job thats easier...If youve ever used copper to back a weld you wont ever want to weld without it...And the screw hole are a breeze to weld when all done...
theres a lot of advantages to using a copper backing strip ,I didnt invent it, I just took it to another level ,backing long seams for butts...Butt ,thanks just the same Brian....