How do you guys weld patch panels - butt or lap?

thanks for this post guys....
very informative and full of info, i have never been good at patch panels but now having read this thread i think i will be more inclined to try my hand at it more ooften now

 

Not to try to hijack someones' thread, but someone mentioned lap welding and the "ripple effect" caused by the extra metal.
I've noticed on a few of the older rides where the cowl vent in front of the windshield had been smoothed, that some had a "shadow" or a perfect line where the original vent was, even though the vent had been welded shut before bodywork had been done, and some didn't.
Always wondered why and what to do to prevent it.
Thanks

Jim

 

When I started doing the rust repairs on the Riv, I tried both lap and butt .( Now remember, I`m a woodworker with no welding skills.)I bought a flange tool and started to replace the floors. I thought it would be easier to do the lap joint but soon found that as my welding skill improved , i found the butt joints much cleaner and easier to do. I am still a Zap and stitch welder but the finished product seems to be getting better.

 

Could you use a wire flux welder? I have used it to put small patches in a floor on a OT car. I also have use oxy/accetalene and flux coated brazing rod. Would you be able to use either of these for whole floor panels?

 

I'm far from calling myself a welder, but I've used that method at times, as well. Here's a shot when I chopped my '33 cab. I screwed a band of sheet metal (from the inside) to even out, stabilize & strengthen the seam. Aside from the obvious welding of the seam, I ground off the screw tips from the outside & blip welded those areas. Another advantage in doing this is that you have no edge "blow through" (or whatever you welders call it) when you weld the seam (which I did with my MIG).

 

All the ways suggested will work. A pro hot rod shop would butt weld it with a tig or torch.

 

Absolutely. MANY people use them for body repairs. My nephew is using one repairing an OT truck right now.

The drawback to them is that the weld is even harder than a normal MIG weld (which is very hard) and The flux core welds tend to be not so attractive unless ground down.

The benefits to them are that you can use them outside (or with the fan on) with no worries, and you don't ever start cussing yourself for leaving the gas on and being out of gas.

My personal preference is to use my MIG to tack things in place, then weld the seams up with O/A

And it was seriously cool meeting you Saturday, Bob. Good luck on that '52. Be sure to let me know whenever you're looking for parts. I don't have a stash of parts, but I'm slowly starting to learn where some of the parts are hiding around here.

 

It was awesome running into you Saturday. I will keep up with your blog so I can learn how to do mine.

Thanks,

 

New cars are built with lapped panels all over. I don't think any of the sheetmetal is butt welded.

The only stuff that is butt welded is precision stuff like transmission parts and they are laser welded.

 

ya, eastwood sells those buttweld panel holders, they work great

 

i dont really know what im doing but i but weld whenever possible pretty much self-taught here

 

True, but you will won't find much of any lapped seams that appear across large panels. Lapping (or backing a seam with metal) across a large panel creates a stiff line across the panel. As all sheetmetal on a car will flex, this has the potential to create a distortion line that will forever be visible in the finished body work. This is why you find lapped joints in modern cars in rigid areas, very short seams, under trim, or some combination of the three.