Welding Sheet metal and body panels!

[SHELBY MESSER]

I've been welding sheet metal together for years and have to grind welds off bother sides of the sheet. I've seen these copper strips that you can put under your weld joint to support the weld and the weld will not stick. Well, I've been repairing a subrail, hard to grind the under side. so I cut a piece of copper that would go in side the channel clamped it in and welded it up, making sure I had plenty of weld, I removed the clamps and the copper strip, had a good smooth weld finish on the under side good enough to prime and paint, of course I had to grind the top side. What I used for my copper was a piece of 2" copper pipe cut it about 2" or what ever, split it and straightened it out flat. I welded with it all after noon and no weld has stuck to the copper. You could use a copper couplen from a hardware or pumping shop. No more burn through. Works great for welding up hole in sheet metal also!!!

I am using a mig welder

[SSsssteamer]

Also for a weld back up I use a carbon block. A brass plate will also work as well as an aluminum plate will too.

[spectria]

I've been welding sheet metal together for years and have to grind welds off bother sides of the sheet. I've seen these copper strips that you can put under your weld joint to support the weld and the weld will not stick. Well, I've been repairing a subrail, hard to grind the under side. so I cut a piece of copper that would go in side the channel clamped it in and welded it up, making sure I had plenty of weld, I removed the clamps and the copper strip, had a good smooth weld finish on the under side good enough to prime and paint, of course I had to grind the top side. What I used for my copper was a piece of 2" copper pipe cut it about 2" or what ever, split it and straightened it out flat. I welded with it all after noon and no weld has stuck to the copper. You could use a copper couplen from a hardware or pumping shop. No more burn through. Works great for welding up hole in sheet metal also!!!
I am using a mig welder

Would love to see pictures of this process...

[rollingsculpture]

yep thats the best way to do it ! did that with holes in my frame too helps keep the weld in place so to speak

[modeleh]

You can also just grab a piece of 1/2" copper pipe and hammer one end flat, then you can bend it sort of like a flat spoon, you just stick it up behind whatever hole you need blocking behind. I usually use a piece about 2 feet long, takes a long time for the heat to radiate up to the "handle" end.
Another trick if someone has drilled holes for mounting something and you want to fill them, you can slip common nails in from the backside, then weld them, and grind off the pointed end.

[spectria]

I've been welding sheet metal together for years and have to grind welds off bother sides of the sheet...
....Works great for welding up hole in sheet metal also!!! I am using a mig welder.

Great post Shelby, can't believe I had not heard of this before. I had gotten pretty good at just using a damp cloth to back up the weld.
Can't wait to try it out.

[Elkhorn29]

harbor freight sells a copper spoon with a handle for welding like you guys are posting about and it only cost $10.



http://www.harborfreight.com/welding-spoon-66785.html

[SHELBY MESSER]

One other thing about welding sheet metal, never grind in the same area until the weld turns 'RED'. If you do the weld will get hot and crystalize or temper, very hard to grind down. Sheet metal will get soft and and cave in. When grinding the weld gets red causing the weld to harden, making the weld harder to clean up. So grind over the whole welded area, let it cool. If the clean up area is too hot to touch with bear hands it's too 'HOT'!!!!!

[fordman88]

i have also never heard of this! seen th e"spoon" tool but didnt know what it was for!! i got a lot of extra holes to practice this on!

[SHELBY MESSER]

Dave and others, My computer or ME is messing up trying to post pictures?? These pictures are showing where I repaired the rib behind the door and under the quarter window on drivers side of a 31 coupe. I used my copper jig-backing plate on the outside and welded it on the inside, My grinding clean up was on the inside with only some miner filing on the outside . The copper backing as you can see I split and made a bevel on both sides to get the copper closer together for this grove. Worked out great. I had a 6" split here to weld up and you could imagine how hard it would be to grind out this tight space without damaging the body line. Hope this may help you guys in your welding of sheet metal!!!!