Thread: Pitfalls of flanged weld seams

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Ok, you guys have heard me talk incessantly about the downside of using flanged seams in sheet metal repair, discussing the ghost lines that can and will occur with these type of repairs. Today I got a short video to show the effect. This car was neat as a pin, with extensive rust repair performed, in basically the same locations as the 55 we're working on. The only flaw I could find in the paint was a line in the finish where the rear tailgate repair patch was seamed. I asked the owner if he had used flanged seams in the repair, and he said yes. He did offer for me to take pictures that others may learn from it..

Butt welds people!!!!!!!

https://www.youtube.com/watch?v=OGhFEfVqxb0


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Yes, totally agreement with you there Robert and I really feel for the chap that owns that Chevy as it is a major repair to have to do all over again to get it right.

Time to bump this public service announcement back to the top, I'm sure we've had some new arrivals that may benefit from it. #justsaynotoflangedwelds

Probably true, but there are more wrong ways to weld any kind of seam, butt or flanged, then there are right ways. I'll speak out for flanged welds, they take far less time, and when a customer is already whining about how much the work costs, it becomes a real dilemma. I've seen butt welds crack, sometimes from grinding, sometimes from the shop trying to make the seam disappear and the weld is just a tad cold. Not everyone has a TIG and endless time to butt weld everything. There are proper and improper ways to do both types of seams, the procedure is far more important then the type of weld.

Using a good weld-thru primer on a flange weld, grinding the excess weld away (again, most of us only have a MIG welder), a good epoxy primer followed by quality seam sealer on the inside of the weld will for the most part prevent a flange weld from bleeding.

IMO, it's kind of like using filler. In a perfect world we wouldn't use filler, with labor prices as high as they are not everyone can afford the extra time and money to do all their body work without using filler.

JMO, I'm not a professional, just a practical hot rodder.

Dave, I'm with you 100%, I think ALL types of welds or adhesion methods are subject to failure in the hands of the wrong person. Here is a picture I saved from the "net" that could be a poster child for "back away from the welder and go back in the house"







This is a repair done on a Chevy II quarter window opening, and is typical of this gentleman's welding efforts. Lack of penetration/cold welds, weld blob on top of weld blob, just about all the defects you mention. I could never get past the piling on of more weld to fix a penetration issue. Surprisingly he does a nice job of final assembly and detail, but I can only wonder how long before the customer is knocking on his door as the hack work comes apart.

My preference with MIG welding has always been focused on machine set up, namely to insure full penetration welds each and every time. I'd say (knock on wood) that I've yet to see a crack develop in following this process, whether grinding or planishing a weld. It's work such as the picture above that drives me to show more details in my posts that perhaps someone in the same boat might pick up some pointers that would help to improve their skillset and give us less of that type of work out there.



Yesterday I emailed the car owner (the one in the video with the ghost line, first post) for additional details on his procedure used (whether it was welded or panel adhesive), just to add to the discussion.

As for the flange repair there was no panel adhesive used and the lip was sand blasted and surface prepped before tacking and then drilled and plug welding approximately every 4 inches,

We went back and moved from one side to the other and did a continuous weld then ground it down.

Having never had any previous knowledge of how to properly make and weld panels this was the only way I was aware of, I know better now.

Thankfully the section still looks the same as when you saw it.

On another note, we used a cheap HF English wheel to make a insert for a 34 Chevy coupe and it turned out pretty good for not having any previous experience with rolling metal, we also had to make and replace all the reinforcement that had been cut out to make a dirt track car we were returning to the street.

The reason I am tell you this is we used the panel adhesive thinking it would minimize vibration between the filled top and the braces, the next weekend when we were ready to start sanding we noticed the panel adhesive drew the top and you could actually see the pattern of the bracing.

We ended up using piano wire to saw back and forth to cut the panel adhesive loose, It took us several weekends to correct the problem but the car was eventually painted black cherry and it turned out perfect.

Hope I answered your questions

I have done some flanged repairs before but I quit using them after a very good sheet metal guy I know explained how much time I could save properly fitting a butt type repair and then there is no metal behind the repair to be seen or hold moisture etc. Another reason I quit using them was when you flange a panel with compound curves, the curves get compromised and it just makes the job even worse. That's no good when you're a beginner any how.

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When they roll threw an auction block the price generally goes down when they look in the trunk and see the flange. One thing I always tell people what to look for when they find that newly restored car for a good price! But on another note some people can louse anything up, and that includes welding a quarter on, whether its butt or flange welded.