Butt weld panel gap

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bob7four

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Have a new patch panel fitted up and ready to weld. I flanged the edge of the existing panel and laid the new panel in. My question is what kind of gap should I have between the panels? The gap seems tight so the panels were fit perfectly. Is there tolerances either way? What is too tight and what would be too large?
 
The gap should be close to thickness of the wire your welding it with.
 
Have a new patch panel fitted up and ready to weld. I flanged the edge of the existing panel and laid the new panel in. My question is what kind of gap should I have between the panels? The gap seems tight so the panels were fit perfectly. Is there tolerances either way? What is too tight and what would be too large?
It sounds like to me that the panel was laid inside of the flange, is that correct?
That would make it a lap weld, not an open butt weld.
If this is the case, then the metal where it touches should be flush, and the area where the new panel and the old panel meet at the step should be no more than 1/4'' all of the way around.
If it is a butt weld, then a gap of about the same size as the wire you are welding it with is the best choice.
Remember to weld using a series of tacks spaced a foot or so apart and allow for cooling as you go to reduce warping.
The actual welding takes a long time this way, but it's worth it in the long run.
Pictures of your project close up would go a long way here......
 
You're speaking of two different welds in one sentence. Is it a butt weld or a flange weld? The butt weld requires a gap. The flange weld does not. Which is it? It can't be both.
 
Flange weld... excuse my ignorance. Not all experts here. The edge of the new panel is close to being tight against the top of the flange.
 
Flange weld... excuse my ignorance. Not all experts here. The edge of the new panel is close to being tight against the top of the flange.

Ok. The way "I" weld a flange weld is like the factory did it. I drill holes through the flange and then spot weld to whatever metal the fanged panel is going on.
 
My bad guess I should have read a bit better
 
If your going with a flange style repair then use metal bond epoxy instead of welding it. No warping, no grinding the welds down, very little filler needed after, and the epoxy seals the back side of the repair from ever rusting. Oh yeah it's also about 3 times faster to do...
 
If your going with a flange style repair then use metal bond epoxy instead of welding it. No warping, no grinding the welds down, very little filler needed after, and the epoxy seals the back side of the repair from ever rusting. Oh yeah it's also about 3 times faster to do...

I've read lots of good reviews about gluing panels on. Who'dathunkit?
 
I've read lots of good reviews about gluing panels on. Who'dathunkit?
It's really the same stuff they have been gluing the tops on the high top conversion vans for like 35 years....you ever seen one of those blow off...lol.
 
It's really the same stuff they have been gluing the tops on the high top conversion vans for like 35 years....you ever seen one of those blow off...lol.

In all honesty, they could probably use silicone calk. I don't think it would ever come off by itself.
 
Totally agree that bonding is good. However, the panels have to fit really well. The adhesive does a great job but gaps found in a poor fit will greatly reduce the seam's strength.
 
To Dartnut... yes panel is laid in the flanged existing metal. Picture is attached.

20191109_075731.jpg
 
To Dartnut... yes panel is laid in the flanged existing metal. Picture is attached.

View attachment 1715420717
It looks like on the right side, the patch panel is actually too high, lay a straight edge, as long as the patch panel is slightly lower you are good to go.
And I would also would glue the panel on.
 
It looks like on the right side, the patch panel is actually too high, lay a straight edge, as long as the patch panel is slightly lower you are good to go.
And I would also would glue the panel on.
Guess it depends on the climate. have seen bonded panels rust right off. No experience with only summer driven cars.
 
Glue and weld? Will the heat from welding affect the glue or is there something that will hold up? The glue would seal that seem nicely.
 
Guess it depends on the climate. have seen bonded panels rust right off. No experience with only summer driven cars.
They bond a lot of panels OEM
Glue and weld? Will the heat from welding affect the glue or is there something that will hold up? The glue would seal that seem nicely.

You have to stay away from the glue like 2” if welding near it.
 
Glue and weld? Will the heat from welding affect the glue or is there something that will hold up? The glue would seal that seem nicely.
Lord Fusor "weld through" adhesive.
Several types. Designed for spot welding if necessary for new car repairs.
Thing is I contacted them re that very thing.
As expected, it would take more than a hobbyist spot welder to accomplish it correctly.
Bottom line, just use the adhesive sans welding if that is what you want to do.
 
Lord Fusor "weld through" adhesive.
Several types. Designed for spot welding if necessary for new car repairs.
Thing is I contacted them re that very thing.
As expected, it would take more than a hobbyist spot welder to accomplish it correctly.
Bottom line, just use the adhesive sans welding if that is what you want to do.

Good to know, I used 3M OEM stuff it said stay away 2”
 
I use Lord Fusor products, just put in a wheel arch patch in my son's truck over the weekend with it.
 
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