August 3rd, 2006 
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The real trick to welding thin metal is to use a wire feed. Just kidding, this tip is to explain how to do it with a stick welder. A wire feed or tig welder is ideal for sheet metal, but we will assume that you don’t have one. We need to establish what is considered thin metal. There is no absolute “according to Hoyle” answer, but I always considered anything less than 3/16″ to be thin. So from this point on we are talking about less than 3/16″ material.
The first thing to figure out is what kind of welding rods and what size of welding rods to use. If you have nice new 1/8″ material, I would go with 3/32″ 7018 rods. If you have old rusty painted up 14 gauge, I might be inclined to use 1/8″ or 3/32″ 6011 rods. You might ask me, why don’t you just grind the rust off? Well if it’s just surface rust go ahead, but if it’s pitted out you will grind all the material away before you get it clean. Not only that, but if you are just doing a quick repair job on something, just weld it. Chances are, if the material is that bad the weld will far out last the rest of the material anyway. Back to my point, 6011 is the rod I will pick anytime. It allows you to move a lot faster than 7018’s will.
As far as the actual welding goes, I like to use a whipping motion with the welding rod following the same direction as I am welding. Basically just a back and forth motion. The reason for this is to keep from building up too much heat all in one spot. If you were to drag the rod slowly you will have a pretty good chance of burning through. If you are welding vertically, don’t be afraid to run the 6011’s downhill. If the material is really thin, I will use the whipping motion downhill as well. I know it goes against some principles of burying slag but, when the material is thin it really doesn’t matter as much.
Most anything that is made from thin material is over welded. Say for instance you are patching an air compressor tank that has a hole rusted in it. You will weld the patch 100% because it needs to be air tight, not for strength. If you are making a section of air duct, you will weld it solid for air and not for strength, you get the point.
I guess the moral of the story is you can do just about anything with a stick welder in a pinch. It only takes a little bit of practice to make it happen. Just grab a piece of sheet metal to get the heat set correctly and go to town. A good heat setting for 1/8″ 6011 rods on thin material is about 80-90 amps. For 3/32″ 7018’s it’s about the same. Everyone is different but, those settings will get you in the ballpark.
Watch the video related to tig welding
muestra parte del proceso de pulido de acero inox … tig welding soldadura acero inox steel pulido
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Certainly…..
You surely can, but if your not experienced at welding thin metal……you should practice on a piece of metal like you are going to be welding on.
If you use a small ( 1/16 inch diameter) welding rod, and using low heat/amps settings…..you can successfully weld on any body metal.
The thing about this is you can only weld about 1/4 inch at a time….or until the sheet metal becomes brite red. If you continue with the metal holding a lot of heat, a small hole will result.
In welding body metal several "tack" welds are better than a continuous long weld. The tack welds will allow movement after the finnish is applied and actually will be stronger.
With a continuous weld the metal body will "warp" from the high heat…..and the weld area will be brittle and can crack with movement.
So a series of tack welds spaced an inch or more apart or so is what you want to do….and if you allow the metal to cool after each tack weld….The body panel will not warp or deflect…the deflected metal is a pain to finish out, with body filler.
I have both types of welding equipment (wire and stick) and for ease I use the stick welder on auto panel patches, its just easier and quicker.
If you are attempting to weld very thin metal, you can use a thicker backing metal strip behind the metal your welding, it will absorb the heat and speed things along.
If your not so good a welder, you can position a wire rod over the crack your welding, as if you were welding the rod to the thin metal…..this will give you more fill metal and dissipate the heat. You can cut a piece of coat hanger and place it where you intend to weld….
If you burn holes in your metal with the extra filler rod, reduce the heat setting and try again….if that just does not work for you…… get a welder to do it for you.
A lot of people can only weld the thick metal….which is easy.
It takes technique to weld thinner metals….so practice on some junk metal similar to what you want to weld….and in 30 or 40 minutes you can get it down pat. Then you can have at some body pannels…….
As a example I have used coffee cans, and weld them end to end with a stick welder in demonstration to student welders in their lab class, and make them practice on the tin cans…..once they can stick them together….everything else is a snap. Once they learn to use a extra rod (coat hanger) as a extra filler metal….they do fine.
Using a filler rod is the same with stick or mig welding, and they get the idea faster with the tin cans…. Then they will remember that when they are welding 1 inch thick metal that large pipe is made from, and especially if the welds are to be x-ray'ed checked for quality.
So all that said…..the answer is yes, and for small welding jobs 70 amps is fine….but you should be able to find a 150 amp welder for the same price…..new, and it will last you a life time and weld anything you want.