Alright, I got a MIG for christmas, and I've been working with it, but how the bloody hell do you weld on sheet metal with it?!? every time I try, I just blow holes right through the stuff, and that is on the lowest voltage setting possible...

Is it on gas or flux core wire? To weld sheet I metal use .023 wire on gas and actually run my welder on either my B or C heat setting. It only has 4 settings A-D. With practice you can use a higher setting and get full penetration. Generally when welding body sheet metal you are only going to be spotting and then moving a ways down your seam and spotting again. After tacking the panel in you start back at the beginning and tack in between the original tacks. Work along the panel like this untill all of the spots add up to a continuouse weld. Because it is just an intermittent spot weld the higher heat settings work and you don't concentrate the heat and warp the panels. For a continuouse weld bead a lower heat setting with a faster rate of travel is required. It's real easy to warp sheet metal with anything longer than about 1/2" long welds. The thinner the metal the less tolerant to heat. Make sure to adjust your wire feed as well. You can hear it when the heat and wire speed are set right. Make sure your metal is perfectly clean both sides and it will be easier to weld.

Practice, practice, practice

search, or look throught the last few pages of the paint & body section, there has been 1 or 2 threads about this lately

http://67-72chevytrucks.com/vboard/showthread.php3?t=135213

http://67-72chevytrucks.com/vboard/showthread.php3?t=118539

http://67-72chevytrucks.com/vboard/showthread.php3?t=90361

these should help

thanks for the info. at this point, I'm at the lowest voltage and slowest wire feed settings, and am using .30 flux core.

what kind of welder are you using?

what thickness is the sheet metal?

Are you running a tank on the welder?

Most use wire size .23 on sheetmetal.

Up the speed of the wire, you might be burning though cause there nothing else to burn but sheet metal due to the wire not coming out fast enough to fill in the void.

I'm using a Hobart welder (dont have the model handy), and no I'm not using gas. I've tried different wire speeds, but the faster ones don't give me the time to run a solid bead and it just blows holes and splatters all along a seam. Good thing I got a spare door to practice on, huh?

I'm using a Hobart welder (dont have the model handy), and no I'm not using gas. I've tried different wire speeds, but the faster ones don't give me the time to run a solid bead and it just blows holes and splatters all along a seam. Good thing I got a spare door to practice on, huh?


solid beads?

you want to do alot of little tacs not solid beads on sheet metal. You'll warp or over heat the metal if you do staright lines.


is this how your weld look like?
LINK (http://67-72chevytrucks.com/vboard/showthread.php3?t=123019&highlight=welds)

not even close. Remember, I'm still a newbie at this, but I'm not getting much in the way of a bead at all, it just cuts straight through the metal. Someone asked about thickness, I'm just welding on the outer skin of a door from a 68 C10 that was solid and rust free.

So bring up the speed on the wire and try just making a tac. You lay each tac over each other like a set of coins leaning on each other.

wow that must be one heck of a welder is it 220v? the only tip i can give is try leaning your gun to one side, adjust you hand travel speed. i am sure you know the sound you are locking for sounds like a frying egg, when you hear that you should be right.

.030 and flux are a part of the problem. It's not the way to learn for sure. If you can convert to gas and .023 wire you will have a much better time of it. At that even with experience the flux core will still suck for sheetmetal.

I have an old Century 110v, that I've had for around 17 years. I leave that mig to run with flux core wire, because it's easier to take to the track. It takes some practice and getting use to a flux core setup. I've built roll cages, back halved cars, full chassis builds, suspensions, bumper mounts, nerf bars, etc. as well sheet metal repair with that machine. Never had a strength or weld issue. It takes a little longer to lay a weld than a bigger gas setup. It takes a little longer to clean up and you don't want to be breathing in the vapors. Usually leave a tannish, powdery residue. Wound up being a great investment, since for that one I've only had to replace the rectifier and wand/gun once.

You have to take into consideration the distance you are welding at and the settings. I basically keep mine at 1/2 speed and high, but I only have speed and hi/lo settings on it. Then change distance and positioning. You really don't want to lay a bead with sheetmetal and a mig. It's more about spot welding in random areas, not letting it warp or burn through. Basically quick bursts. You should get to know your machine a little more and practice on scraps, until you are comfortable with it. A gas setup is much easier to use as others have said to convert it. If you can get the flux core down, you won't have any problems with any gas machine. If patching over a panel, I drill around 1/8" holes through both panels, about the width of cigarette pack. Bigger holes and you might start to burn through. I do the same distance with butt welds and randomly fill in little by little. An auto darkening helmet also makes it a little easier, instead of flipping a shield or lens. Just keep trying on scraps and don't get frustrated, it'll do it's job.

a good weld should sound more like a buzzer.

I'm with X on this one.The "bacon and eggs" sound applys to smaw.MIG should have a electrical buzz sound,no snapping or popping.

Get yourself a thicker piece of metal to play with. Then move on to thinner metals. Don’t damage your panels trying to get a FEEL for welding. I use .035 wire with argon/co2 mix, but must guys seem to like the thinner gauges. Flux core burns a little hotter then solid wire (at least it seams that way), flux core is mostly used when you have a DIRTY area to weld (rusty, paint, crap) or your working in a windy area where the gas is just being blown away and not doing its job.
If you don’t have a way to switch to welding with gas don’t worry about it. It just takes a little more practice and patience with the FC wire.
Always try to keep the gun at an angle when welding, try welding in both directions PUSH or PULL the wire across the metal to see the effect it creates on the weld.
I hate spot welding, I don’t have the patience for it, but we don’t have a choice on body panels. Structural areas only need tack welds to hold it in place, then you can run beads on it as you see fit. But be careful because these areas WILL twist and pull if you spend too much time in one place. This is my first time welding body panels and I still have some learning to do. Mostly I learn after I realized I F****D something up. I'm use to welding 1/8 plate or thicker. I have three G6 X-RAY certified welders working with me and I DONT invite them over to my house to weld my body panels because they will screw them up just as fast as me. LOL

My best suggestion is to get a couple of rolls of wire and scrap metal and play..play...play. There is no substitute for time spent welding. Maybe offer to weld your friends stuff....practice on there stuff not yours..LOL