The Stovebolt Site Forums The Shop Area Paint and Body Shop Butt weld or flange?

Anyone with experience with welding sheet metal? My 54 needs some panels replaced and I bought a gas MIG welder to do the work. I have some butt weld clamps to ensure proper spacing, but I have never used them. Another friend said he would only weld panels after crimping a flange in the body and cutting the panel to fit in the flanged area. What do you all say about the options? Is it worth buying a flanging tool and learning to use it, or just butt weld the sheet metal as is?

This is a question for the guys in the Paint and Body Shop...

My answer would be to butt weld as flange welding makes it hard to work out any warpage (can't hammer/dolly the weld you just made to stretch the metal back out) and it will trap future moisture causing the rust to come back.

Mike B

Another vote for butt welding. You've got to do some planishing to keep from having to use pounds of body filler.

Look up MP&C's posts to learn up on how to do it. Robert is a master metalworker.

I'm only a beginner at this, but I think that it may depend on which panel you are replacing.

I butt welded my floor pan section, but it would have been a lot easier and faster to do a lap joint. As far as external panels or anything that's going to be visible, I'd only do butt welds for the reasons stated above. For a beginner like me, lap welds are far easier than butt welds when it comes to sheet metal. The thinner the joint that you are welding, the more skill it takes to do it right, IMHO.

Thanks guys, butt weld it is. I've never done the flange method, but the guy that told me to do it that way builds for a living and says he does all of his that way. I can definitiely see your resasoning for butt welds. I'll practice on scraps, then improve on the farm truck and then be brilliant on the '54 daily driver.

In addition to Mike's comments, using a flanged seam leaves your panel with the possibility of a ghost line in the paint finish that will show EXACTLY where the seam is. One layer of sheet metal will expand and contract more quickly than two layers. Given enough heat (think truck/car show in the sunshine) and enough cycles of heating and cooling (expanding and contracting), the panel will show a ghost line. This won't happen overnight, but will take a year or so. But rest assured, it can and will happen. This video shows a repair done on the bottom of a wagon's tailgate where a flange seam was used. The entire car had been restored by the owner, who did a beautiful job. The only flaw I could see was where the flange repair resulted in a ghost line.... watch the video.....







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Interesting thread.
I've used flange welds and never noticed any problems later. Never put on a "Show car" finish, but really pretty single part original looking ones.
What do you do with patch panels that come with flanges? Cut them off and then work to match the edges?

Jim, depends how anal retentive you are We have eliminated most of the factory "pinch welds" on the 55 wagon in the rust prone areas, like where the rear pan welds to the lower quarter. The factory flanges were eliminated in favor of a butt weld that is no longer a rust trap. My contention is that OEM's don't use pinch welds because they are the best, they are used as they are the fastest to get something down the assembly line. On coach built cars of yesteryear that were not part of the assembly line process, you saw butt welds and gas welding..

On the flange repairs, my suggestion is to not use them in the center of a panel that the factory originally has as a one piece panel. The factory doesn't use them on exterior panels where they are intended to be an invisible repair, we should not either. The patch panels that come with flanges already IMO are pressed that way for the guys that don't yet have stones enough to butt weld. Cut the flange off and trim the panel fitment nice and tight, and butt weld them into place for best results.

Thanks for all the comments. I had to look at the video twice to see what you were talking about. I kept looking at the truck in the background, expecting a zoom in to show the line! But it seems pretty obvious that butt welding is the way to go. They guy that said he only flange welds builds cars for others, so maybe he has never seen the line appear later.

Flange joints have their uses, such as putting a repair section into a floorboard, etc. Just don't use them to create a seam that was not there before in a panel that's visible from the outside. I've got a flange-making tool that fits my air hammer, and it's a real time saver on a patch panel that's going to be out of sight when the job is finished. I also butt weld with a needle-sharp, tiny flame from an acetylene torch when necessary, and do metal finishing with NO body filler in some places.
Jerry

Maybe I should buy the flange tool then, since I need to replace the floor. I can see the sense in that. And I won't have to worry bout moisture in the floor, since I am undercoating all of it when I get it done. Thanks again Jerry. Sounds like I need to take a trip to TN and sit at the feet of the master for a day or two.

Although I can do body work (even taught it in high school for several years) I'd rather get a root canal than try to make a living doing it! Give me a lathe, a boring bar, a valve grinder, a die grinder, and a few micrometers, and I'm in hog heaven building "Go fast- - - - -Turn left!" engines!
Jerry