Aaron Cake

iTrader: (1)

I know there are some very experienced body workers on this forum and I'm hoping for a little guidance. Heavy body work is not something I have done before. The most I've done is patched a few holes here and there in non-cosmetic areas, and filled small things like emblem holes.

Yesterday I welded a patch panel into a door (shaved door handles). I took great care to shape the panel (about 6" x 3") to match the door contours perfectly and it laid so flat in the hole that you couldn't tell by running your hand over it or sighting down the door. I made a few quick tacks, quickly cooling each one with a blast of air. Panel and door was still straight.

Then, I burned the whole thing in. I alternated side to side and up and down, making one tiny weld at a time and immediately cooling it with a blast of air. After 45 minutes, the panel was welded in place and the metal was only warm to the touch.

It was then that I noticed that the area was not straight anymore. Not even close, really. The area I welded had sunk in about 1/4", and some of the contour of the door below the area had collapsed inward and thus sunk about 1/4" as well. So, why did that happen?

It's not something I won't be able to pound out after a few hours with a hammer and dolly (and a steep learning curve!). I was able to make some progress straightening it out with just a small hammer and block of wood. But I'd like to avoid that as much as possible in the future when I do the other door.

I welded it with a Lincoln 120V MIG. The current was set at max (uh, 90A I think) and the wire speed at "4.5". I wanted the current hot so that I could make each weld in about 1 second and keep the heat localized. Running 0.030" wire.

Now, after some Googling and reading, I think I can immediately recognize a few mistakes:

1. Too much current (should be 60A or so?)
2. Wire too thick (should be 0.023")
3. Need to weld from the center out

And sheet metal is always going to warp a little. But is there anything else I need to know? I've also read conflicting advice that I should not have cooled the welds with air, as that would cause them to shrink and thus pull in the metal. I don't weld much sheet metal so this is new to me. I do have hundreds of hours behind the TIG torch on everything from steel to magnesium, but body metal is something I don't have experience with.

just startn

iTrader: (33)

First off, Way to big of wire. Put .23 In there. Never cool the metal off faster than natural air with air. This shrinks the metal then you have problems as you see. I see you took your time and went very slow. My father tells me theres a Happy medium, going to fast, well its common sence, but going to slow the expand and contract will make nice waves, Just tak, wait a sec, tac, wait a sec ect ect. Another thing to look into is theres a tool for making panels fit, and i will tell you its the ****, called a punch flange tool. Just type it into google. Also To cool you can use a oily warm rag. But you really dont need it. Any other questions just ask
https://www.rx7club.com/build-threads-294/vert-restoration-101-heavy-update-2014-a-893883/

jgrewe

iTrader: (1)

Its like how to get to Carnegie Hall...

I usually start with .023 and an amp per thousandth thickness with body metal. If you're working near a crease you can bring the amps up a little because of the added strength. I've done the 'million spot welds' method and spot welds followed by stitching. It is really hard to not get some growth just because of the nature of what you're doing.

With the low amps having clean metal is that much more important. The best filler after welding is All Metal. Don't try to use it for finish work because its a bitch to sand but it seals up the seam so you won't have a problem with moisture behind your finish filler later on.

Aaron Cake

iTrader: (1)

I picked up some 0.023" wire this morning as well as the tips to go with it. Also bought a few differently shaped body dollys so I can work out the warp as best I can. Obviously it will never really be back 100% as the metal has shrunk, but that's why they make (metal) filler. No harm in a little filler here and there, after all, that's how people get a straight paint job.

Tonight I'll be pounding on the door to try and straighten it back up as much as I can. Then I will start fresh on the other door with the proper wire and far less current, also without any forced cooling. I will practice on a little scrap metal of the same thickness to figure out wire speed and current settings.

Thanks guys for the confirmation that I basically did it wrong the first time.

just startn

iTrader: (33)

If you can know someone in autobody repair, See if they have a Punch Flange Tool you can barrow for 15min. It works wonders. You will probably never want to return it.

Aaron Cake

iTrader: (1)

And that's the one thing I forgot to buy when I was buying tools earlier today...

How would that work on curved panels? Wouldn't making the flange straighten them out again?

just startn

iTrader: (33)

I never made curves, my dad makes curves all the time, he goes a little then makes a v in the piece so it curves. Idk i never tryed it he makes it look easy but any professional makes anything look easy lol. If your doing the door handle i would just cut the door handle into a Square.

PvillKnight7

iTrader: (16)

Bolt or clamp a heat sink behind the weld. If that's not an option get it as close to the weld as possible. I've used big chunks of AL or brass stock. I've tig welded 0.025" 5052 aluminum and I had to use a 8"x8"x1" piece of brass stock behind the weld to keep the aluminum straight while I welded in small stitches. Heat sinks work with mig and brazing. Another big tip is take your time. Weld a few small stitches then walk away and work on something else. Come back in 15-20 mins and weld a few more stitches. However it takes for the material to cool down close to room temperature. Try to let the material air cool slowly and fully before adding more heat. You should be able to touch the previous weld with you skin before you start another.

Aaron Cake

iTrader: (1)

By curves, I don't mean a round panel, but a contoured panel. Such as one made to patch an outer door skin or fender. Seems like the flanging operation would straighten it back out and then make it hard to get back into shape.

I spent about an hour last night pounding on the warped area from behind, using a block of wood to reach it inside the door and a small hammer with plenty of medium pressure taps. It is coming back into shape very well. I'm confident that I'll be able to get it to the point where all that will be required is a skim coat of filler as one would expect to find under any straight paint job.

I'll also see if I have a big chunk of something that can be used as heat sink for the other door. Though now that I've basically fixed the warp in the first door, I'm more confident that I can fix any issue with the second should it occur. Doesn't take too long to get a feel for how the metal wants to move back into position. It wants to back to it's original shape and just needs to be encouraged.