I bought a DVD recently from this English guy I saw on you tube that shows you how to shape metal using only hand tools. Some of you may have seen it. It's a pretty good video but he recommends using oxy-acetylene welding as the best method when working with body panels. His reasoning is there is less distortion and you can planish out the weld once done and limit the amount of filler required. With MIG and using filler rods you end up with an uneven weld that can have more distortion and trying to hammer out the weld can make it worse requiring more body filler. Also if you hammer it and then grind or file it smooth you can end up with weak points because of the unevenness.

On here I don't think I have seen anybody use oxy-acetylene welding. Everybody is using MIG. I got a MIG setup and know how to MIG weld but have never used it for bodywork. I was thinking about picking up a oxy-acetylene setup and trying it out at least for the outer body work on my 914. Any structural work under the skin I will use the MIG.

What are other people's opinions on welding methods? Should I just save my money and stick with the MIG and grind and fill it like everybody else.

Personally I can't imagine using oxy-acet. for doing body work. . . Yes the welds *can* be smaller with less grinding, BUT whole sections of the panel will warp severely. You would definitely get good at hammer/dolly work and metal shrinking.

If you get good at setting up your machine and hone your techniques, there can be little grinding needed and even less hammer/dolly work to do.

Try both on a couple pieces of flat sheet metal a see which type causes more warping. . .

Are you going to use a solid rod or flux coated brazing rod?

I've found MIG is just easier overall. With everything set up properly, there's very little to grind off. Setup and cleanup are a snap. I can generally clean up with just a blending wheel rather than a grinding disk. If you're gonna be going over the weld with a hammer/dolly, you can always normalize it prior to beating it with a simple propane torch.

He didn't use a filler rod unless he blew a hole which didn't happen very often. He just butted the two pieces of steel together and basically melted them together. when he did use a filler rod he didn't specify what type of rod he was using. When he did some aluminum welding he said to wipe the flux off so assume that rod contained flux.

I probably used a couple water tower sized Ox Acc tanks in my life before I ever got a mig welder. When I bought my first mig welder it was a giant thing.

I thing both methods are fine but perfer mig these days. Specially on light gauge sheet metal. It's easier to have one hand free with the mig. I agree about mig welds being brittle. I have cracked some while bumping and filing a bug fender once. I ended up having to anneal it.

I ONLY gas weld 4130 tube. TIG has a tendency to fail as it cools too fast. The experimental air frame guys gas weld all their planes.

I really like my TIG but I keep running out of gas.

Oxy-acetylene filler is cheep. Back in the day I watched guys use old coat hangers....don't laugh, old coat hangers are very similar to the material used for bodies.

OA is much more of an art form than MIG. OA anneals the steel as you go
but, hammer/dolly cold works the metal and needs to be annealed no how for ease of continued working....in my experience.

When/Should you move into tight spaces MIG is the cat's ass, so OA does not replace MIG entirely.

I MIG weld structure panels and 'hidden' panels, and only pull out the TIG when I'm working fenders/flares/exterior panels. I did some work on the OxAcy setup way back, but I would let a newbie weld on a car with a MIG a year before I'd let them touch it with an OxAcy. Gas welding just needs a lot more experience before you can be effective.

Playing with Gas welding can be fun, but I wouldn't use it for serious work unless I could call myself an expert.

Yes coat hangers or break the flux off of an arc welding rod. It is an art form, and requires a lot of practice just like any other method of welding. I have seen some great work done on very thin metal using OA. If you use a small tip you should see no more warpage than with mig. Just keep moving around the area to be welded to avoid getting panels too hot.

The OA would be preferred on exterior body panels over MIG
the only problem is that no one has enough skill or patience to use it...
(including me)

I did some custom fenders with it once when I was really welding a lot and practiced up.

I went back a couple of years later to repair accident damage and couldn't pull it off. You have to be on top of your game and really using it regularly.... only the pro's have that kind of frequency.

it does warp less
it is harder and requires more skill
it is more flexible, less brittle

I stopped by the welding supply shop on my way home from work tonight. I was thinking of just getting a kit and some tanks and playing around but money made up my mind for me. The cheap kit which actually looked pretty good was around $200 but the tanks for the set would be about $400! For a nice Victor kit you were looking at $300 to $400 plus tanks. So $600 minimum for a very basic setup and who knows how much more for other extras like tips, goggles, books, etc. I think I will just stick with my MIG for doing all my body work and use that money to buy a nice paint gun or something else useful for the project. But, it would have been nice to give it a try.

MIG is the right answer.

OA is excellent for doing body work. It works as well as mig once you get the hang of it. You dont want to use just any old torch. You want to use a Henrod or an old Dillon torch. They are low pressure guns and have very small pinpoint flame.

There are videos on youtube that show how to do it. I went to Ron Fournier metal shaping class 5 years ago and we did some welding on aluminum with a torch and a tig. The tig welds would crack and break once you start to planish it out. The AO welds hammered out so smooth you cant tell where the weld is. Its alot more work but the results can be impressive if you practice a bit.

Tin Man sells a small victor series torch that he likes and has been selling for years. http://www.tinmantech.com/ he sells videos that shows you how to do real metal working.

Ron Fornier is an amazing fabricator too and has a good 3 day class to get your feet wet if you are in the Detroit area. He also sells supplies to weld body panels. http://www.fournierenterprises.com/About%20FENT.html

If you want to experiment you dont have to buy your bottles. Most towns have a welding supply store that leases the bottles. I pay about 40.00 a year for each of my 6 bottles.

M I G "The glue gun of welders".

I assume that is a negative comment. Is the implication that MIG is for amateurs and the pros would use OA? If you want a quick easy fix use MIG but if you want it done right use OA.

They had a leasing option but it was $75 a bottle per year, to fill it it was twenty some bucks so the guy said unless you are a pro and going though bottles it's better just to buy it for $200 and get it filled as needed. Not sure if the math makes sense but that is what he said. These were for full size bottles. I have seen much smaller bottles before used for cutting/welding. Maybe I can hunt around and find a place that has smaller bottles.

Based upon the comments here I want to give OA a try. After just investing $1200 into a nice MIG setup i couldn't really justify spending another $700 for an OA setup if it does the same thing. But it is starting to sound like OA may be the way to go.

I'd go with the biggest tanks you can move around, K cylinders, as it is a pain to have to bring them back to refill.
I'm not sure but the one guy at the welding store said they charge just as much to fill the big cylinder as the small one - this was for argon for my tig.

If done correctly OA has some advantages over MIG, but as stated it's an art form that takes skill that only comes from lots of practice. Almost anyone can make decent MIG welds in an hour or less.

The problem I see with MIG is failure to practice before welding on the car, and bubble gum proud welds without any penetration. Get some metal just like what you plan to weld and practice, practice, practice.

The other thing to remember if you are new to welding, is be sure to put the covers on the cylinder bottles whenever you move them. Lots of guys have gotten hurt (or worse) from compressed gas bottles getting the valve broken off.

You can assume all you want and there was nothing implied at all. I was only stating what some people say about MIG welding. I mistakenly assumed you noticed the quotation marks and knew what they meant. I have O.A., MIG and TIG and prefer MIG to them all mostly because it's easy. I like using TIG but get tired of having to continuously sharpen the damn tungsten rods.

I find this process very good.
http://www.youtube.com/watch?v=ldl6fIDGQ5E

Glen
The 914 should be dropping in any time....

The benefit of OA welding is:

If using filler that is identical to the metals to be joined, it is called fusion welding.
That can even be done with No filler if the two pieces have enough sacrificial material to join the pieces without leaving a void.
You are melting both pieces directly together.

If you are using AO for "brazing" then the filler material melts at a lower temperature than the parts to be joined.
It is essentially soldering and requires a flux to clean the oxides from the base material and to bring the impurities to the surface.

Brazing and soldering have the benefit of being able to rework the parts again and again until you get it right.
You can even solder aluminum, but the "solders" used are fairly rare and expensive.

With MIG welding, you get one or two tries at it, and you will be replacing base material.

I have never done OA on car body parts, but I can see the benefits.

I can imagine brazing steel flares to steel body with less warpage than MIG, but as said above, it is a "lost art" for most people.

Stu

After doing a lot of all types of welding, the control of both heat and metal is unmatched using O/A or tig welding for me. The ability to walk the pool of molten metal at a controlled pace on thin sheet metal makes it ideal for bodywork. With any method, the key is to not spend too much time in any one spot for too long in an effort to minimize warping.

TIG will definitely do the best job for larger projects since you get heat on/off much quicker. Setting the proper gap on panels prior to welding makes a huge difference on weld integrity, if done properly, the weld bead on the back of the panel will look similar to the front. Butting metal sections tight together makes it almost impossible to get the right penetration on the weld bead, and usually forces you to apply more heat (not good) to get a good weld.