Sheet metal welding tips needed

[DenCo40]

I've got an old fj40 I need to weld some sheetmetal on.
I have been welding for years but only big stuff like .250 and up. I tried this past summer to weld a little sheet metal on a little wire feed lincoln mig but with disasterous results. I have searched the forums and see that I do not use flux core (obviously) and light guage wire. What is the best setup for sheet metal wire guage size and what gas to run?
Thanks

 

[fj40charles]

C25 shielding gas and .023 solid wire.

 

[PAToyota]

As Charles says, 0.23 wire to start. I use my usual shielding gas. Tack about every inch to two inches around the joint. Then go back and tack next to each original tack. Repeat. Working with small tacks keeps you from blowing through the sheetmetal and also reduces warping. When fully filled in, grind everything flush and a bit of hammer and dolly work to smooth things out. Skim coat of filler to even the last of it up. Prime and paint.

 

[haryv]

So is that how car/truck body sheet metal work is done? by tack welding and not running a weld bead ? I have some big holes in my fender and would like to cut them out and weld in a used replacement fender or, just temperately weld in patches to keep water from coming into my truck. The holes are on the inner wheel well fenders of a fj60.

 

[lowtops]

Don't try to weld beads, just tacks welds as described above. If you have the amperage setting right to get penetration on sheet metal you will blow a hole trying to run a bead. If you are able to run a bead on sheet metal you are probably not getting full penetration and the metal will still get hot enough to warp.

Tack welds are not pretty and take time to do, but are the proper way to weld sheet metal panels.

I agree with 75/25 shielding gas and .023 wire. No flux core.

 

[ar2stp48]

sheet metal welding

All good advice. There is an extensive discussion of automotive patch panel repairs on The Garage Journal I think it is in the fabrication section.

 

[Gusb]

All good advice. There is an extensive discussion of automotive patch panel repairs on The Garage Journal I think it is in the fabrication section.

x2 - Robert (MP&C) is one guy to watch/learn from on that thread...

Don't wait until the welding is complete to do a little hammer/dolly, that's one mistake (of many I've made...
Welding in patch panels - The Garage Journal Board

 

[Mace]

Esab just came out with a mig wire that is specifically designed to be ground away. I have not tried it yet but saw it being demo'ed at SEMA. Looks like really neat stuff. May want to look into it.

 

[DenCo40]

Thanks everyone. I ordered my wire, tips, and gas. Maybe if I get some warm weather I'll give it another shot.

 

[Zack1978]

What about .030 wire, is that bad for sheet metal?

 

[Mace]

.023 is easier

 

[LandCruiserPhil]

If you have gaps to bridge, even if you dont, back the area with heavy stock like 1"+. Your tacks will not stick to the heavy material and it makes it easier to bridge the gaps and keep everything flat.

 

[PAToyota]

What about .030 wire, is that bad for sheet metal?

Not that it is bad, but that it is more difficult. You'll end up adding more heat and more metal to the weld and increase your chances of blowing through.

 

[77TPIFJ]

try to use this if you havent already done it
Welding Spoon - Welding Accessories - Welding

 

[Dell]

try to use this if you havent already done it
Welding Spoon - Welding Accessories - Welding

'
X2

^ I used the same HF spoon to fill nearly 50 some holes on my M100's tub.

little advice... don't let the steel nut at the bottom side (holding plate to handle), ground to the sheet metal.

the spoon don't like that much. :whoops: LoL

I also used a 4" X 4" X 1/2" thick block of aluminum as a backing plate on mine... worked awrite...
wish I had a copper ingot that size tho'

copper seems to work best...
alloy or copper... the thicker the better as it helps dissipate heat better then thinner stock.

 

[geolar]

Welding Sheet Metal Patches

Use compressed air to cool after every run between tacks. I used to work at a body shop back in the day and this is what we did on the Porsche turbo flares. Tig is way cleaner but most of us do not have one. The Mig just uses more material that you end up grinding off.

 

[KLF]

try to use this if you havent already done it
Welding Spoon - Welding Accessories - Welding

I have the same spoon. Used it to fill in a bunch of small holes, worked pretty well. Well worth the $10.

 

[Elbert]

I'm no welder but years ago I worked in a body shop for a few years...I've watched the guys weld many times. Its basically spot welding or tack welding a little bit here and then over there and then somewhere else varying the location as to to avoid warping the metal. Very easy to burn/blow through.

First order of business to me would be to round up some junkyard sheet metal and practice.....before you touch anything of any value. You are just on the metal for a second or so with the mig.

 

[Gadjeep]

You can always use Nickel silicon bronze wire and run your machine EN. That stuff lays out nicely, plenty strong for non structural and requires very little heat. I use it all the time with my TIG machine. A small spool for a MIG is less than $30 IIRC.