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Old 08-17-2004, 06:06 PM
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warpage

can tack welds be cooled with water or a damp cloth to avoid warping?

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Old 08-17-2004, 06:57 PM
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Yes. I usually use a sponge, squeeze it above the spot and let the water cool it down. Keeps the panel straighter!
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Old 08-17-2004, 11:06 PM
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I have never understood this, maybe Randy can shed some light. Cooling SHRINKS, it will NOT keep the panel from warping. It will just warp in a different way.

There are some uses for cooling a weld to control it, but I feel it is way wrong to make a blanket statement "Cooling the weld helps".
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Old 08-18-2004, 07:36 AM
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I'd be interested to know also. I would guess that the metal is going to do what it wants to do regardless of the cooling.

I mean, if you were a very consistant weldor...and you welded one panel without quenching, then you welded an identical panel with quenching...I think they'd end up looking about the same.

I've never once seen Wray quench a weld. He uses Tig and he is very controlled about it, he takes his time but there is inevitably heat and shrinkage...which means stretching by hand to return the panel to what it should be.

Besides, even if you DID manage to contain the shrinkage, you're still going to have a weld bead that should be planished down...right?

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Old 08-18-2004, 11:16 PM
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Cooling with compressed air is a better deal, if you're going to cool it at all. Doesn't make good sense to me to have water present when trying to achieve good welds, not to mention the fact that the moisture will get through the seam and start rusting the metal on the back side.
Cooling the weld will only keep the heat from creeping too far into the panel. It may or may not reduce the shrinking (warpage).
What you must remember is that the metal shrinks along the heat affected zone, so you have to go in and stretch within that area to remove the warpage. NEVER work outside the heat affected zone, as you will stretch metal that is not damaged. The only place the metal is affected is within the blued area. This is the Heat Affected Zone, or HAV, as we commonly refer to. It is always best to remain in complete control of the metal. Don't weld up the entire seam and then try to fix it! It's so much easier to get the panel tacked and stretch the tacks out before proceeding.
Read this post for more info.
http://www.metalmeet.com/forum/viewt...hin+sheetmetal

You may have to register at www.metalmeet.com to view it, but it should answer your questions.

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Old 08-19-2004, 08:22 PM
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The reason i asked in the first place is because I was welding in patches for the drivers door handle and lock holes.
i tacked in both peices and when " filling the gaps", I would let the metal cool down to where it was not uncomfortable to touch with a bare hand, but the door still warped.
BUT, it warped in a very strange place, the center of the "crater" from warping was just bellow the bottom of the lock hole, and the lock hole is a couple inches below the handle.
It's not so much that I want to quench the weld, I just want to help the surrounding panel cool faster and I don't have an air compressor.
My MIG leaks gas and if I waited for the door to cool completely between each tack, I would probably have to get a freah bottle of argoshield.

and I'm about to start the pass. side in a few days
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Old 08-19-2004, 11:41 PM
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It's not a matter of quenching or not. I normally do not worry about cooling between tacks too much. If I see that the panel is starting to get out of control, I just beat it into submission!! Stretching the heat affected zone, post welding is the key.
In your case, the metal is NOT damaged down where you think it is. The problem spot is ALWAYS within the heat affected zone. The metal shrinks from the heat introduced into the panel and as a result, things tend to move. In this case, it moved at the point of least resistance, which will always be the case. It's most noticeable because there is a hole there for the lock. Simply stretching the metal along the blued area from the weld will relieve the stress and it will go back to normal!

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Old 08-20-2004, 12:22 PM
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Should i just patch the pass. door with body filler and not risk warping another door?
I mean, it's gonna need filler anyway
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Old 08-20-2004, 04:48 PM
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No,
Stretch the weld seam only and you will see that the warpage will disappear. DO NOT work outside of the blued Heat Affected Zone though. With a little patience and understanding of what the metal needs, you can finish it off to the point that no body filler will be needed.
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Old 08-20-2004, 07:31 PM
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I am learning body repairing at school and my teachers showed us to push out the edges to be welded. Of course it is not by alot, maybe 1 or 2 mm so when you weld it will shrink down because of the heat. From the side it would look like this :

______/ \______


It seamed to work but I am not yet a professionnal in welding so maybe someone with a lot of experience can tell me if its a good way of working. It is harder to strech a weld because it is thicker so maybe if we make the metal shrink while welding to the way we want it, it would be much easier to not use any body filler.

Of course if we strech the edges at first it might be harder to weld since the metal will be thinner and will tend to create holes.

I don't know if you understand what I mean. If not I will try to reformulate what I wanted to say.
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Old 08-20-2004, 09:15 PM
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Alecigio,

A straight butt weld is much better. The method you show will work, but so will tons of other methods. Why we make this so hard is beyond me. For the most part, the majority of us here are dealing with older cars where access to the back side of a panel isn't a big deal, like it is on late model vehicles. Your teacher is showing you a method that can be used somewhat effectively on late models cars, but for restoration/expert panel work, it's a wasted step, as we will be working the weld seam to perfection anyway. By chamfering the edges of both panels along the weld seam, just as you would with heavy plate steel, you will be able to weld it with less heat, add a bit more filler rod and achieve better penetration. By following up by working the heat affected zone, you not only relieve the panel of the stresses caused by the welding process, but also cold forge the materials, producing a very strong weld. If butt welds are performed properly, you should be able to cut right across the weld seam, and never tell it started out as two separate sheets of metal. Done properly, it's just as one solid sheet of metal. Try some metalfinishing on your own and blow your teachers mind!

The unfortunate thing about trade schools is that they rarely teach you the proper methods of repair procedures. It's normally some time saving, production body shop CRAP. I work in a body shop and have tried to train a few guys straight out of some of the nations top auto body trade schools. (How these schools get a reputation of being good is a mystery to me.) I would much rather take a guy who has absolutely no former training and start from scratch, rather than take a poor brainwashed guy who has been 'taught' the latest, greatest way! When you get out into the workplace, keep an open mind and listen to the guys who have been doing body work for years. You will find that they will be the ones who will teach you what you really need to know.

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Old 08-21-2004, 03:27 PM
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Thank you Randy Ferguson for the information. You are right, the teachers only show us how to do the minimum to be durable for 2 or 3 years. They don't try to show us how to make perfect panels. I'm getting pretty good at welding at school and I can barely see I welded the pieces and my teachers are impressed

When I try at home it's a different story... On my car there is rust and I have flux cored wire MIG. I am able to do pretty good welds on my car but i have some problem with the finition since it is a whole car and not only fender like at school.

And by the way, what do mean with "butt weld". What kind of weld is this? I speak french and know a lot of english but I have some problems with some words. Could you explain it to me? Thank you very much.
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Old 08-21-2004, 04:57 PM
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Hi Alecigio,
Butt welding is a term we use when we are talking about joining panels buy just bringing them together at the edge so they just touch, without overlapping. Lap welded seams are BAD!! You will no doubt get by for a while, and if you're lucky, maybe even years, but I've had bad experiences with lap welded sheetmetal and just don't do it anymore. I'll give you more info if you need it, or you can search the website for "metalfinishing" You will find several posts on the subject that will help you.

Your problem with welding at home is the flux core mig. Get a gas kit and lose the flux core. You'll instantly have better results!!

Randy
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Old 08-21-2004, 06:19 PM
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Thanks againg Randy Ferguson. At school they showed us to lapweld and butt weld but they want us to use lapweld since it is easier to use bodyfiller over it but it doesn't make great welds. I would like them to show us how to properly make restoration of parts but they don't seem to have enough time since we are 40 students for 2-3 teachers at the same time.

I know there is a big difference between the 2 wires but I still have about 4-5 pounds of this wire and I dont want to trow it to the garbage. My MIG is ready for gas so I won't need to change it. Maybe I'll try to sell what I have left to a neighboor.
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Old 08-21-2004, 06:57 PM
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Wanna learn to make panels?????
Check this out!!
www.metalmeet.com

Randy
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