Welding to thinner sheetmetal question-

[SCW]

This really isn't terribly advanced-

I'm trying to weld some reinforcement onto the body panels. The reinforcement is 16ga steel and I can use a mig welder with either .023 or .035 wire, either gas or not. I tried to do this already by welding about an inch at a time and cooling everything down with a very wet rag, and while I was welding I left the rag on the panel to keep it from getting too hot. The end result looks like crap, as it cooled the body panel got pulled all over and distorted like crazy, so I'll be getting a new panel and doing it again.

How do I weld to the thinner metal without the warping?

Thanks-

[Captain Ron]

If it's going to be a cosmetic weld, you need to do it with one of 2 things.

Pulse MIG or TIG. You will still have problems running more than 20" of weld in the horizontal direction on any body panel.

Welding razor blades is good practice for this. :D

--ron

[SCW]

Pulse MIG? I don't have access to a TIG, and this only has to be moderatley cosmetic, but the way it warped after the first time I need to at least improve it some.

The reinforcement patch is about 10"x12".

Any other advise? Thanks-

[IntrepidXJ]

a bunch of spot welds alternating sides so there is time to cool in between

use the .023 with gas

[cracker]

http://www.millerwelds.com/products/mig/comparisons/millermatic_350_350p.html

Sounds like a pissed off bumble bee :D

[ponyracer1]

a bunch of spot welds alternating sides so there is time to cool in between

use the .023 with gas


Only way you can do it, I run the .30 wire without any probs though. Also you can run a 110V flux core if you want, just more cleaning afterward. Don't cool the welds down, your prob causing more warp then your preventing, as well as the welds can crack due to the sudden temp change. The trick is to not get the metal hot in the first place.

[YELLAHEEP]

I think your welding an inch at a time was a big part of the warping. If you look at any photos of body guys doing patch panels (yeah, they're working with same gauge metals, but the process is the same) you'll see that they do spot welds - no continuous beads. When I've watch a small body patch panel being welded into place, the guy put spot welds on like you bolt up a wheel - he started at one end, then went to the other end, then the top, then the bottom - then back to the side he started on. He continued all around until he had the spot welds about 1/2 inch apart all around. Then he filled in between the existing spots, still alternating sides to keep things from getting too hot. Sure seemed to keep the distortion down. I'm thinking that the process doesn't change with thicker metal being used on one part of the seam.

My .02 anyway.

[Mr.OverKill]

I think your welding an inch at a time was a big part of the warping. If you look at any photos of body guys doing patch panels (yeah, they're working with same gauge metals, but the process is the same) you'll see that they do spot welds - no continuous beads. When I've watch a small body patch panel being welded into place, the guy put spot welds on like you bolt up a wheel - he started at one end, then went to the other end, then the top, then the bottom - then back to the side he started on. He continued all around until he had the spot welds about 1/2 inch apart all around. Then he filled in between the existing spots, still alternating sides to keep things from getting too hot. Sure seemed to keep the distortion down. I'm thinking that the process doesn't change with thicker metal being used on one part of the seam.

My .02 anyway.X2 100%

[Captain Ron]

http://www.millerwelds.com/products/mig/comparisons/millermatic_350_350p.html



Interesting you found this comparison. I have the Lincoln PM in the shop now.

What a pile of crap compared to the 350P.

Plug welding is an invitation to rust. From the inside out. In a lap joint situation tacking and stitching isn't going to get you much further with MIG most of the time, X2 100% or not.

Do I have to show you guys everything? :D

--ron

[Mr.OverKill]

Do I have to show you guys everything? :D

--ronoh yes all mighty welding goorue, you DO!! :D


besides, if its a trail rig ( i assume it is ) rust isnt an issue, but i may be wrong.

[Ludakris]

on "Trucks!" they just glue the stuff together... :roll:

[Ghost]

on "Trucks!" they just glue the stuff together... :roll:
LMAO! :shocked:

[old_man]

Don't laugh. I use the professional body working adhesives from SEMA and they will surprise you. If I was overlapping a panel, a thin coat overall would yield a stronger bond than a weld. It remains somewhat flexible so cracking is not an issue. The applicator gun runs about $75 and the adhesive is about $30 a tube. They demo it by gluing two sheets of metal with about an inch of overlap. After curing, they are pulled apart in a press. The metal fails before the adhesive.

[BrettM]

Don't laugh. I use the professional body working adhesives from SEMA and they will surprise you. If I was overlapping a panel, a thin coat overall would yield a stronger bond than a weld. It remains somewhat flexible so cracking is not an issue. The applicator gun runs about $75 and the adhesive is about $30 a tube. They demo it by gluing two sheets of metal with about an inch of overlap. After curing, they are pulled apart in a press. The metal fails before the adhesive.
know of any decent alternative that doesn't require a $75 applicator gun? does the one you mentioned work well with aluminum, stainless, galvanized, etc?

[ChicksDigWagons]

The technique I've used welding XJ rear inner fender seams back together was .023 wire, with a C25 mix gas. Basically, I place spot welds along the seam at 1"-1.5" intervals. Then go back and place a spot right next to it all the way along. If you're following what I'm saying the weld should be like this:

. . . . . . . <-First Pass
.. .. .. .. .. .. .. <-Second Pass
... ... ... ... ... ... ... <-Third and so-on


This isn't optimal, but its a good compromise of low warp and reasonably easy/fast procedure.

[SCW]

Don't laugh. I use the professional body working adhesives from SEMA and they will surprise you. If I was overlapping a panel, a thin coat overall would yield a stronger bond than a weld. It remains somewhat flexible so cracking is not an issue. The applicator gun runs about $75 and the adhesive is about $30 a tube. They demo it by gluing two sheets of metal with about an inch of overlap. After curing, they are pulled apart in a press. The metal fails before the adhesive.

Something like this is what I should have done in the first place. I'd be very interested in it, maybe I can scab together some kind of applicator?

[1996cc]

They have those small epoxy tubes for sale at the parts stores. I think that is what they used on Trucks. Has anyone used one of those?? For non-structural areas, I wouldn't be afraid of it (for a wheeling rig anyway).

[old_man]

http://www.sjdiscounttools.com/sem39747.html

http://www.sjdiscounttools.com/sem70029.html


Search, they have various formulations for different applications.

[Clint]

I remember when I worked at a body shop a few years back. We had a Tacoma come through with a smashed bed side. We just drilled out the welds and the side nearly fell off. After that we used that "glue" stuff and stuck it back on. Worked pretty good. I know the guy who has the truck and it still looks great.

[SCW]

Excellent! Does this stuff need to be mixed like normal epoxy, or can you squeeze it straight onto the panels and stick them together? I assume you would want paint-free surfaces and good clamps.

How well does it work on large panels? Should the center be chopped out and only glue on the edges? Clamping in the center of a large peice would be problematic (theoretical question, mine is a small piece).

[Clint]

The stuff we used came in a tube and was applied like caulk you would use on tile. The panel we "glued" on was the side of a truck bed, so it was fairly large, but only needed clamped along the top bed rail and a few places where it met along the bottom.

[MJ_Chubs]

3M, Lord, and Loctite would be good places to start. I used a combination of Loctite structural adhesive, self-drilling screws and structural rivets to patch the floorpan in my MJ.

Went from this:
http://i60.photobucket.com/albums/h24/brcook03/MJ%20Build/OverallUnderseatPatch.jpg

To this:
http://i60.photobucket.com/albums/h24/brcook03/MJ%20Build/Newfloorinstalled.jpg

[old_man]

The stuff comes with a nozzle that is about 6 inches long. The adhesive mixes in the nozzle.

[roscoecoltraine]

i hear that you can drill holes into the thinner sheetmetal and then take the reinforcement plate, put it behind the thin sheetmetal so you can see it through the holes and tack it at the holes. From what I understand, that is how they weld the unibody. Just a though. Im not sure if thats what your looking for though.

[GSequoia]

Hey Ron. If we can't afford a Pulse MIG can we just get a buddy to flip the switch REALLY fast on and off?

[Israel]

Hey Ron. If we can't afford a Pulse MIG can we just get a buddy to flip the switch REALLY fast on and off?

You can't flip a switch fast enough. You'd need to buy a push button start and tap that thing like you were back in your video game days. :D

[JohnR]

I work a little with sheet metal, but the only pic I have on-hand is of 18gauge sheet metal L joint. .023 wire, straight co2.

http://www.laredoperformance.com/spotwelds-small.jpg

Best way to NOT warp the panel is to do overlapping spotwelds in small sections, but a simple tack isn't enough. You have to run it hot (seems counterproductive, but a short and hot spotweld has less heat to surrounding metals than a long and cool tack). Basically turn the wirespeed down, voltage up, and hold it long enough that the toes wet really well, then move foward to the leading edge of the previous spotweld, and hit it again. So in the width of a single spotweld let's say, 3/16" diameter (yes I realize the toes and the root should be equal, however the only downside is slower desposition rates and wasted wire), there would be 4 or 5 overlapping tacks by that time. Do an inch or two at a time, and let it cool NATURALLY. Flopping a wet rag over the hot metal is the SUREST way to cause warping as well as some funky internal stresses that cannot be released except by annealing and peening. Not really neccessary for sheet metal, though :)

[Rust Heap]

We use a lot of 3M products at work and they perform very well.

3M #5036 for steel
3M #5047 for aluminum

http://solutions.3m.com/wps/portal/3M/en_US/Automotive/OEM/Solutions/Exterior/Structural_Adhesive/

[BIGMO32]

if your set on welding it you should use a tig, otherwise id look into going the adhesive route. there are ways to mig the sheetmetal without getting heat distortion but its alot easier to just tig weld it.