butt welding thin metal on a curved join

I am gearing up to weld in the first of the wheel wells on my '30 coupe this week. I have been practising butt welding sheet metals which is not perfectly straight, the mating line between old and new being curved and not at all 'perfect'.

I just found this video and as butt welding is the preferred method and I am sure there are many new'ish to welding I thought I would post it in case it helps. I at least found it to be useful.

http://www.youtube.com/watch?v=i4q1TExpmfY

 

Thanks for posting I can always learn something that's a very good video.

 

I'd look for another how to video. That guy is a shit show and is doing it wrong. The way he was welding you will have bad results after grinding.

 

What he's doing works, but it's better to have someone on the ready with a hammer n dolly to gently stretch the weld as it cools. This is also done best with ESAB EZgrind so the weld doesn't crack. No more that 3 of those "stacks" he made, get outta the way quickly and let the hammer get at it. Doing it solo, you need to reheat the welds and to stretch them but that's a tough call most times. Heavy old fenders, blind repairs, mig's all ya got, it can definitely work. It's just not preferred, but the best weld comes from the best possible fit and any form of stretch you can give the weld.

 

I am not experienced enough to agree/disagree but WHAT is it that he is doing wrong???

Saying 'look at something else' is less than helpful without knowing why...

 

I've heard people talk about this Ez grind but have never seen it. I've asked my welding supply and they say there is no such thing, unless its silicone bronze?Also hammer welding with mig is nearly impossible. It's too hard of a weld and will cause more damage then if you don't hammer.

 

Pat, the local supply shops dont' have it, I wound up buying it online. Didn't find it to be all that much better than regular MIG wire. Won't buy it again. But it's not silicone bronze.
If you want a weld you can work with, do TIG or gas.

 

It's not exactly easy to explain but you want to hold your peace in position. Make one tack per every 1 1/2 as you do that make sure it is even with the other peace your working with. Then between those 1 1/2 welds make another spot weld so you will have about 3/4 between each weld then you can go back and fill a little bit. I fill about 3 to 4 spot welds in a row then move 2 or 3 3/4 slots ahead. Repeat then go back and do the same thing untill it's compleatly filled. Now the majority of your warp is gonna be from your grinding unless you do it the rite way.

 

Thanks. Maybe ill have to test it out.

 

Didn't mean to multi quote. On that last post. I'm on my phone and have big thumbs

 

OK, that helps. So basically, spread out your tacks to prevent heat build up. Then, go back over the panel. In attached image, do all A's then B's and so on...

 

Yep

 

Easy Grind Mig wire, grinds about the same as standard wire, when is is a small tack or small seam.

On larger weld there is a noticeable difference.
Used it for years, in the prototype trade.

http://www.airgas.com/browse/productDetail.aspx?Category=374&product=ESA130TF43


.

 

I've had very good luck stretching mig welds, but the problem is that it's a 2 man job. The weld needs to be just tapped hard enough to stretch it, and has to be done while it's hot, the glow just going away. Also, if you are going to stack the welds like that it takes a high level of discipline to cover 50% of the prior weld. 2, no more than 3, hammer until the "ball" of the weld looks like the head of a nail. With the right helper you can do a panel with mig, metal finish, no filler. Easy? Not really, but not hard. Why bring it up? Not everyone has a tig or O/A get up at home. I prefer tig over ANY other form of welding. O/A just gets too fuckin hot for me, makes a huge HAZ, takes a higher amount of work to get things back where you want em, and to repeat, for me. Some do it as well as I can tig. Good for you, keep it up...

 

Highlander, I've been oxy-acet welding since I was 12. (a Master Artizan taught me, and hammered discipline in soundly! LOL

I have learned to tig, but find it much more difficult. Just let me ask: Did you just tig first, or previously arc or mig? Thanks...

 

Here you go........


http://www.youtube.com/watch?v=2Nk4JFKj9hM

 

Geez, he is FAST!!!!!!

Thanks, very helpful.

 

Whats wrong with most mig welds is they are done"cold".
by that I mean they are a zap that does not penetrate usually,OR they are gobbed up with a tall bead [caused by a longer exposure] and heat warped as a result...

This causes the bead to be hard and brittle and gives the mig a bad rep as a result,when hammering the weld comes up.....a hotter more "instantaneous" weld[with same amount bead on both sides of sheet] is able to be hammered without breaking....

I do a lot of mig welds on sheet steel and have a method that helps some.
I do spot welds only/no bead welds....
I do not use a 110 welder any more,that is the main thing as I see it that causes the ill welds.
I use a Hobart 210,it is set on 2 and 3 depending on the situation......the wire is set mainly at 3.
this gives a hot enough weld instantly to penetrate and also by the virtue of the short exposure of intense heat, you don't warp the piece.
I'm not talking blue metal here now.
I do the spacing as mentioned as well as adding this.....
I use my other hand on the surrounding metal,and when you cannot leave it there you are putting too much heat into that panel....it takes a lot of "wait" time man!

 

Guys, I am looking at the wheel well on my A and it is a loooong join between old and new metal, and thin too.

It strikes me that one of the biggest aids in keeping things straight is to reduce heat in the surrounding metal, to avoid warping.

So, a question... how good/bad/HORRIBLE an idea is it to use a soaked cloth behind the panel to help keep heat down. Before those with 800 years experience respond telling me I am an idiot blah blah blah, this is a question, nothing more... it would just seem to be a potential way to reduce heat/warpage. Am I way off base with that thought?

 

There are heat dissipating products on the market that work much better than wet rags...one in particular that seems to work very well is a clay product that is applied to both sides of the weld seam. Do a web search and you should be able to find a couple of brands that would work for you. Alvin is just one company who makes this product. http://www.alvinproducts.com/heat_block.asp

 

wex65, why not try out your theory on some scrap and see for yourself. What works well for some, others will say the world will end if you try it......

 

a wet rag will make it shrink and you will fight it all the way, the moisture will cause rust.
If its thin on the original you could try pressing a chunk of aluminum or copper against the back to help with blow out, just go slow, tack it all up, make sure both edges of the weld area are aligned (hammer+dolly) and weld 3/4 inch sections in areas that are apart from the last weld

 

Thanks guys. will play around and grab some heat sink too.

Went to buy some metal yesterday and saw something like this there. Should have grabbed some then...

Will report back on whether I turn my wheel well into a roller coaster or not!!

 

OR, you guys could gas weld, and stop fighting the MIG altogether...........O/A is a far better process for sheet metal.

 

I don't disagree but I have a decent MIG and have never O/A welded. I have heard it is more of an art and don't honestly want to spend the next 3-6 months learning a skill to get these wheel wells on!

 

I did O/A in my youth. No matter how clean things were I always seemed to get that POP while I was going along unless I'd upped the oxy more, then too much heat again. I know it's a fine line and a learned discipline, much like anything in this shit including creating a paint surface. TIG came much later in my world and I never looked back. Pedal control for heat, no worry of open flame, aluminum is a breeze. MIG is handy too for a lot of things, but it too gets a bad rap because it's grossly affordable by comparison and many who've never even seen a video or read a book can just start throwing wire at their stuff. We've all seen that guy a time or 20

 

Too bad. What you've heard isn't true. It's just a skill learned like any other. Probably easier to learn to gas weld sheet well than MIG sheet well. But it's easy and fast to learn MIG half assed.

But you can make it work. Good fit up and clean all surfaces. Learn on scrap, then move to the car. Follow the rest of the advise in this thread. Good luck.

 

Mig welding has such a bad rep and for what I am not sure......it is precise- it is strong.

it will weld when the back side is dirty-rusty and contaminated with paint or even undercoating....whats to bitch about?

turn the heat to the correct setting =get the gaps as good as ya can=and all is possible....we all cant have a tig and we really do not need one for patch panel repair.....
I think the most common thing causing problems with Mig users is the small 110 underpowered machines and also using .023 wire results in gobbed up weld beads, a 1/2" tall.....

Here is a picture of a simple example of how you can weld thin steel to thin steel[Taiwan replacement quarter panel] with controlled heat.....

notice the seam is in a corner and I didn't even clean the paint off to start,but when it was done the paint is not burnt off even a 1/4",but it is securely welded together....try that with a Tig,or Oxyacetylene=even the black coating isn't burnt off....this was welded with my 220 Mig set on#2 heat and#3 wire speed[.030 wire]
I did not run beads /just spots.......

I did have to touch up a couple pinholes but its bodywork/not critical suspension parts....what else does one need on old car body repairs?

 

The OP was asking about butt welding with a mig.

 

I thought that was what I just showed a 24" joint irregular butt joint welded with a mig..... you can post something yourself if it would show it better.........