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Old 07-07-2017, 05:59 PM
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MP&C MP&C is offline
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Default Pitfalls of flange welding sheet metal

Ok, you guys have heard me talk 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..

This video shows the effect.. Butt welds people!!!!!!!

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


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Old 07-08-2017, 02:20 AM
Maxakarudy Maxakarudy is offline
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It's a shame to see hard work like that going to waste.
Factory cars did use lap joints in certain places, but they were always leaded over & the lap joint was lower than surrounding panels to allow the lead some depth for strength.
Butt welds scare the crap out of a lot of restorers,both professional & amateur, mainly because they are mig weldig & also they don't know how to metal finish properly.
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Old 07-08-2017, 06:31 AM
elavir elavir is offline
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Hi Robert, how exactly is this flange weld made? What I can find about flange welds is that there is another sheet standing in a 90 degree angle on it.Is it a sort of lap joint, folded inwards?
Cheers Richard.
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Old 07-08-2017, 06:45 AM
hot rivet hot rivet is offline
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I have seen the same problem with the panel prepared with these http://www.eastwood.com/manual-perfe...prep-tool.html as well as the conventional offset joggle/lap joint.
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Old 07-08-2017, 10:09 AM
crystallographic crystallographic is offline
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I have not seen problems with offset lap seams .... at least on my work ...
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Old 07-08-2017, 10:51 AM
John Buchtenkirch John Buchtenkirch is offline
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If you use a stepping pliers or joggling dies to join the outer skin chances are good that you will see a ghost of the edge of the upper step showing thru your paint & filler work at a later date. Ideally quarter panels should be changed at the factory seam and leaded but my commercial body shop customers rarely wanted to remove the back windows so I sectioned the C pillar (commonly called a sail panel in the trade) low enough to avoid all that extra work. I used to overlap the C pillars and mig weld them without any ghost problems. The trick was to cut right angle slits in the lower panel so you could in effect shrink it and to only overlap about a quarter inch. The mig weld would shrink slightly as it cooled and the weld seam area would drop inward slightly allowing some room for filler which was probably why my body shop customers didn’t have ghost problems. Many of the places I sectioned panels had no backside access which made hammer & dolly working butt welds impossible. ~ John Buchtenkirch

P.S. A small percentage of my business was changing quarters for guys that were restoring muscle cars. They were the only guys that would remove the back windows and pay me to change full quarters at the factory seam. They removed everything that unbolted and the glass, then I could change the quarter panel, outer wheelhouse and trunk floor skirt in 9 to 11 hours per side. I changed over a thousand quarters so I got pretty quick and was good at getting correct gaps, that’s why many times body shops sent me those restoration customers.
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Old 07-08-2017, 11:58 AM
crystallographic crystallographic is offline
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...Depends on how you make your joint using the offset method....
Some methods will show - others will not.
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Old 07-08-2017, 02:37 PM
John Buchtenkirch John Buchtenkirch is offline
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Quote:
Originally Posted by crystallographic View Post
...Depends on how you make your joint using the offset method....
Some methods will show - others will not.
Kent, I agree. The example on the bottom is going to do much better because you could almost argue that it’s a butt weld. The example on top will likely end up leaving a ghost line in the paint work at a later date. ~ John Buchtenkirch
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!GHOST LINE.jpg
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Old 07-09-2017, 12:28 PM
crystallographic crystallographic is offline
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Quote:
Originally Posted by John Buchtenkirch View Post
Kent, I agree. The example on the bottom is going to do much better because you could almost argue that it’s a butt weld. The example on top will likely end up leaving a ghost line in the paint work at a later date. ~ John Buchtenkirch
Attachment 42307
Righty-O JB.
I have done the single offset lap seam, 36" vertical, 18 ga, for an old tour bus resto at HAC, long ago. Welded as you indicated, top to bottom. Then took a scarf tip and whisked off the lap flange and hammered and filed the joint smooth. No way was I going to butt that thing ....
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Old 07-10-2017, 02:40 PM
Lee T Lee T is offline
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I have heard of ghost lines in butt welds, what might cause a ghost line in a butt weld with tig torch?
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