I do a good bit of tigging making chassis parts, motor brackets, and do a nice job of it (usally), but don't let me get near a piece of sheetmetal with it!! Well, that ain't completely true, I can weld good size emblem holes shut and make a clean job of it, but if I try a small patch panel I'll warp it every time, no matter how slow I go! And You can "see" where I welded, even after grinding the area with a 36 grit disc. What the hell am I doing wrong? I've got a Miller Square-wave 180 , a nice machine by the way, and had a old Sycrowave 350 before that, so equipment ain't the problem, its the operator! I also have a Miller 200 Millermatic mig setup that I've always used to weld patch panels, but wire is so much harder to hammer out, I thought I'd learn how to tig it for cleaner jobs. Anyway, any tips or pointers would be appricated.
Sounds like you're welding too hot and too cool at the same time. The warping is coming from excesive heat. Weld an inch or so at a time and try to use some kind of heat shield on the panel to isolate the heated area. Also, hammer weld to reduce the warping as you go along. Try to move from one area to another instead of working the same bead continuously across. If you can still see where you welded, that could be a sign of insufficient penetration. That might be from trying to weld cooler to reduce the warping. You're probably better off welding it hot and hammer welding. I welded a shit load of .035 stainless yesterday, it sucked. I preffer MIG for sheetmetal work like nosing and decking. Good luck
I am a definite TIG newbie (probably haven't laid over 6 feet of bead yet), but I do know that a tight fit is KEY. With a MIG I can fill a gap, but no way can I do that and make a TIG weld look good.
Thanks 57Joe, I do skip around , I'm guessing MIG may be the better way of the two, but I'm one that always want to learn something new, and if I'm gonna take the time to learn it, I wanta be able to do it right! Anybody else?
Mig weld it...no need to tig weld it...your on the panel longer, exposing it to more heat and therefore warping it.
Wrong. The gap you're trying to weld must be tight. I don't even think about welding until you almost can't see daylight or a flashlight thru the gap. Turn it down to about 70 or 75 amps. (I only use about 1/2 to 3/4 throttle even set at 70, just use 70-75 as a max.) Use 16th" red Thor. Tung. (red) Sharpenened to a needle point, taper should be twice as long as it is wide. Also, make sure you grind the tungsten so the grinder marks go stright to the point, or your flame will wander and tornado around. And if you accidentally touch it down, stop and regrind or put another freshly ground one in if it acts any different than a newly ground one. Just about any gas cup, stay small though so you can see. Tungsten stick out should be at or a hair less than 1/4" , some don't recommend this, but it works for me, I even have it out 5/16 or so in a tight spot....I've learned to overcome the problem with excessive stick out, but you'll be ok at 1/4". I just eyeball it. Gas at about 25. Go forward not backwards. Use .023 or .030 ER70 S6 mig wire cut to about 12" lengths. I use .030 mostly though. I can almost weld my panels in without filler at all, I only dab 3 to 5 times per inch. Stop after one inch and hammer & dolly it. And make sure you can see 100% clearly, a bad hood will screw you over. Mostly make sure you're comfortable and try to hold the torch like a pencil, like you're writing with it....or at least be able to steady it by sticking a finger out on something stationary....most times I'm not worth a damn freehand. Mig welding is very brittle on sheetmetal I wouldn't mig weld a body panel for anything, well some things are ok, like spotting & plug welding wher two things are sadwiched and not susceptable to bending, flex or vibration. Try hammering a mig butt-welded joint, it'll shatter and fall apart. You can bend a mig butt-welded panel back and forth about 2 to 3 times and it'll snap. On the other hand you can tig butt-weld two panels and grind it flush on both sides, even under flush, and it's still as maleable and soft as the surrounding metal....after you bend it back and forth about 15 times you might break it on either side of the weld. Usually not even then though, it'll just keep working back and forth softly. You can tig sheetmetal and bend it a sharp 90 right on the weld and it won't even think about being brittle or cracking, impossible with mig. Mig is a cold weld, it takes the metal from cold to hot too fast and embrittles it. I welded a whole cowl on this 34 all the way around, from bottom, up and over, around the cowl vent and down the other side, all one piece, no warpage, might need a super thin skim of lead in a couple of places, no plastic filler will be used. If you like to finish your panels inside and out so the weld/repair is invisible, it's just about impossible with mig, the weld is so hard you'll remove too much parent metal on either side of the weld and it'll still show a lump of the hard mig weld in the middle......or unless you're some kind of super grinder, at that point a guy should have been spending that time improving his actual welding skills.... You can't really see it by the pic but the welds are flat or barely high enough to grind off....when you feel it with your hand it feels smooth, no grinding. The other two are the rear subrail sections for 34's. The welds are only hit with a Rol-loc scothchbrite disk and almost made them flat. I'd rather do things a certain way to cause a bunch of tig welding than another way that might have been easier. Just start out on some 20 or 22ga. running the tiniest bead you can, microscopic even....then work it up from there to good penetration (watch the backside) & joining two well butted pieces. Just imagine you're welding with a needle, staying as small & close to the metal as poss. (on sheetmetal anyway). Forget the world outside of your helmet & that little weld puddle.
tight fit and hammering your welds are key to a good tig weld, keep the amps around 70 and dont try to build the weld up, what you should be doing is trying to melt the two peices of metal together only use a little bit of filler rod to keep a decent puddle also try welding about 1/2 inch at a time and then hammer and dolly it and skip around dont start a new weld right next to the old one if you still cant get it than mig it, when i mig sheet metal i usually weld 1/2 inch and cool it right away this creates nearly no distortion but is also a much more brittle weld
Great post, Roost. There seems to be a lot of misconceptions about TIG welding, and welding in general.
I agree with Roost, except for the mig welding comment. You can actually do a very nice butt welded panel that is metal-finished after mig welding...more trouble than it is worth to me, but others have done it. Randy Ferguson did a very nice post on metalmeet (I think) showing this. I would expect it to be more brittle than a gas or tig welded panel though. One thing that helps me when welding a panel is to not worry at all about distortion. You can not stop it. But you can deal with it by accepting the fact that the metal will shrink and need to be stretched and smoothed after welding. I routinely gas weld 10" long sections of metal without worrying about warpage at all. John www.ghiaspecialties.com
It's been so long since I've logged on I had to re-register but thought Id share my own trial and error cuz I was just suffering from the same prob. What worked for me was to back my seem with a block of brass (or copper). If you can clamp it, that works best. It did 2 things. 1 it let my gas fill the back of my bead leaving it a lot better on the backside and 2. The brass worked as a heat sink so it didnt burn my metal if I didnt get off the pedal quick enough. Like I said, Just thought I'd share.
Damn fine looking work Roost, you've restored my faith that in fact a nice looking job can be done with a tig rig!
I agree with roost. He must be bad ass to not have to use that much filler which is where the quality work comes in. The mig is for welders and the tig is for craftsmen. Sure the mig will get the job done. but the tig will give you the quality your effort deserves. Rodger
Roost !! That is some of the best advise Ive ever read. I just followed your instructions to the letter, and what do ya know?? It works!! VERY WELL!! My life will never be the same Thanks for sharing
This is great tech post. Please... include some info on polarity settings and specific gas used for welding sheetmetal, aluminum, and stainless. Thanks,
Stainless and Mild Steel = DC straight and if you have High Freq put it on start Aluminum = AC with High Freq on Constant as for gas pure Argon for all three, although if your welding heavy aluminum, a few cfh of helium mixed in with the steady flow of argon will help tremendously. Also a pure tungsten -- usually "green:, will help with aluminum...you can mess with the ac balance as well, but that gets a bit too "into it" for the average guy. Those are all good starts that should help
Roost, Thanks for the info. I just bought a lincoln 185 with the pulse setting. Can't wait to fire it up. Good tips. Thanks again
I responded to your earlier thread about tig welders. You went with the Lincoln 185. I have the same welder. I think you will like it. I love mine. The only thing I would change is adding a liquid cooled torch if I was going to weld much aluminum.
John, after you have run a long bead and the panel is all distorted, do you start your straightening proccess by hammering "on dolly" on the cold, welded seamto stretch it back out? If so, in general, how much (if any) work needs to be done outside of the heat affected zone? I'm just curious about this because you one of the only guys that I have ever heard say that they ignore the distortion until the weld is completed, or at least quite a ways along.
I'm a novice with welding, so I'm basically soaking up all good info as I find it. This is a really valuable post, but I got one silly question: Will the above settings also apply to a european 400 volt machine, or will it need a different setting? Thanks.
Hi Chris, If you stretch the weld, usually you will get right back close to where you want to be quickly. On dolly to start. You can also bump up the weld area with a dolly a little bit here and there. In some cases, I don't let the panel go too far out of control without doing a little stretching, but I think trying to control warpage is over emphasized sometimes. If I were welding in the middle of a low crown door or something like that, I would be a little more cautious so as to keep from getting big wows in the panel that might not pop out so easily. The first person I saw doing long gas welds without a care was Kent White. That taught me something. To get your contours back you should be able to stretch and smooth the weld area only because the rest of the panel is not being shrunk by the weld process....only pulled a little out of form...much like you would curve a piece of metal slightly by pulling on it, and expect it to go right back when you let go. The area that turns blue from welding is where the metal has shrunk. John www.ghiaspecialties.com
Hey Fellas, just my .02 worth...if you can and it's available, take a welding class (night one's if you work) at your local community college. You will be surprised what you learn in there. We did everything from MIG, TIG, SMAW (stick), Oxy/Fuel, and Plasma Cutting - I enjoyed the class so much, I joined AWS (American Welding Society)! A lot of your information you posted here is awesome, especially from the folks who have a grip of experience. But the real way you learn is not from reading posts or books - but by getting your hands dirty and getting some hot slag down your shirt! When they taught us TIG on welding Al and FeC (Steel), they told us to set the Argon at 15 cfm (units?). Also, AC for Aluminum because it will clean off the AlO2 layer as you move along. Also, like many have said here, for Al welding, make the end like a ball by running it DC on some steel (2% Thoriated W) and zapping it for a few seconds. Anywho, great info fellas!
"Cool, thanks John. So you stretch (hammer) your welds cold?" __________________ Chris Hi Chris, Yes, I treat the welds like any other metal...hammer cold to stretch. John www.ghiaspecialties.com
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