I like the mig (mainly because its all I have). The heat is way less and helps lower the amount of distortion. Like everybody has said so far, do it slow and steady and hammer it back to a nice fit and then grind it down to a nice finish. Also I really like the buttweld clamps from Eastwood. They help a lot making the gap just right and help to hold everything in place.
Lots of good info here, my $.02: Mig is ok for meatball stuff- flooring, body bracing, etc. For outer skins, a Dillon/ Henrob torch or tig are the best way to go. I use tig, keep something handy to hang the torch over, or a cardboard box to drop it into, to grab the hammer and dolly. Fit butt joints as tightly as possible, sometimes use magnets to hold for tacking, make sure both sides are shiny clean. Don't skimp on shielding gas pressure. Use a minimum of filler rod, weld and inch or so then hammer on dolly to stretch and planish weld. I find as I've aged my eyesight has deteriorated, I need magnifier glasses inside the helmet to see the puddle well enough. (Seeing the puddle is key!) Norton and others make sanding discs with big holes in them that allow you to see your workpiece as you sand. I use a shrinking disc on a 7" grinder to level panel and remove waves when necessary. Practice a lot.
For floor and interior panel fabrication I use only a TIG welder. I try to spot weld as much as possible. Usually drill a 3/16 hole equally spaced in a returned flange and fill the holes. This is ten times stronger than a butt weld. If I have to butt weld something like a set of radiused wheel tubs. I'll hammer weld them as close as possible then use the planshing hammer and finish them on the English Wheel
That would be great Jeff.Take a lot of pictures. I have no idea on how to gas weld.I have been reading that some people when gas welding will weld it with out using filler rod.When they do not use filler rod it leaves a little undercut around the weld but it is livable.Your going to paint the car anyways. My question is if you do not use filler rod is it a week weld? Other questions I have are what tip do you use,or is it a personal preference.Does your gap have to be as tight as if you were going to tig weld it.Do you use any sort of backing when gas welding.Also do you planish your haz as you go or when you are finished.I have seen people gas weld and they make it look real easy,what I did notice was the heat band was quite a bit larger.which would mean there would be more stretching involved. Then I noticed how David Gardiner gas welds,he leaves a nice small even heat band.I need to buy his video,I have just been to busy buying tools here lately. From what I have heard it is a great video,here is a link if anyone is interested.www.metalshapingzone.com http://www.youtube.com/watch?v=IGElSHzm0q8 I just know David from talking to him on forums but his work is incredible.
Hi Johnny, First a little history. Please bear with me on this. I had just purchased a new Miller TIG welder and was well on the way to learning how to use it effectively when I had a problem with my heart. After my heart stopped twice in the emergency room, I had to have a permanent pacemaker placed in me. After my hospital stay, I inquired about whether I could continue with my hobby. My cardiologist said, "Absolutely NO tig welding". But with simple safety precautions I could do some mig welding though. What a waste of a brand new tig welder! That's when I decided to take up O/A welding so I purchased a Henrob 2000. It sat there for a long time before I finally got up the courage to try it. Recently, I had purchased David Gardiner's DVD. It is excellent. After viewing it for the fourth time, I went out in the shop yesterday and started practicing with my unused Henrob 2000 "his way" of O/A welding. It really works. You should try it! I am not experienced in O/A welding but I got an even HAZ all the way down the welds with the actual weld being flat with no lumps or waves. There was a slight depression in the center of the weld but that's exactly what he shows in his video. The welds were so strong that I reshaped the flat sheet steel into a bowl and didn't crack the welds. Peace, Chaz (the other one)
Chaz I have even run gas welds through shrinking dies without cracking. I've tried David's method and it works. I don't like not using filler rod. Out in the middle of the panels I'm not concerned with strength of the undercut weld, but up to an edge I use filler rod. The biggest thing is getting a good neutral flame. If you don't your weld will be weak and brittle. Johnny I'm not saying I'm the best in the world. I will take pictures and explain the best I can. If I'm doing something wrong and it is pointed out it's to my benifit. You can only show so much with text and pictures. Chaz just curious, can you use a scratch start without the high frequency? Jeff
A few factoids regarding metals, quench, temps, filler. I'm no renowned expert and have tried many techniques for every possible reason. I have to agree with the zero gap joints on panels. Basic metallurgy and the function of a shrinking disc tells us what happens when high heat hits a panel. Water or compressed air quenching will make it brittle. The weld will shrink and since a weld essentially fuses with the parent metal it will also shrink hence the need for a filler and hammering to stretch the joint back out to where it started. Mig, Tig, or torch, mostly the same. O/A welding to me is more of an art form than a recommended process these days. As has been said already it takes a lot of time to get O/A welding down pat, lots of time to reach perfection. All welding procedures take practice and anyone picking up a Henrob, Tig torch or squirt gun needs to be 'all in' before they get started. The arc on a tig can reach temps as high as 9000 degrees at full tilt depending on the output of the equipment. Consider the energy trapped in the poles of the planet when they're assaulted by the sun lighting up the inert gasses in our atmosphere. Yup, just like that. Having infinite temp control under your foot makes the Tig process the prefered method on the face of things, just like lead being the prefered filler but anyone in the biz has to deal with reality daily. So what about the love/hate Mig relationship? I posted already a way to get through it with good pro results in very little time. Yes it's 2 guys doing the job but it's still faster since the hammering is going along with the weld process without doubling back and the need for filler (plastic) can be all but eliminated (did I ever say how much I HATE bondo?). I didn't read some of the links here, but I didn't see any reference to annealing the sheetmetal. Pretty much everyone reading this saw on TV our HAMB bro JESSE JAMES anneal a steel panel for a gas tank on a chopper show. This can help with the process on those early car projects where the fender and body sheetmetal is as thick as a modern subframe. If you lightly 'soot' the sheetmetal with the O/A torch and then evenly burn the soot off with a neutral flame without getting it red-hot you'll soften the metal, relax it's molecular structure. The only way it stays that 'soft' is to let it slow cool. By the time it's been shaped, beat on, wheeled, welded, and generally abused into submission for it's new life the hardness is back. We did it this week on a Packard tail panel with a complicated radius around it's corners. What I noticed on this repair was that the hammer and dolly work went pretty easy for a welded joint. It's not required on everything but there's some occaisons it helps. Also if this was mentioned above and I overlooked it, sorry bout that.
Sorry highlander but Jesse James was making that tank in aluminium, you cannot anneal steel like that. Gas welding is the best way to join sections of panel in my opinion. Distortion is caused by uneven heating of the sheet metal. If you heat a piece of steel it expands, as it cools it contracts beyond its original state so if during the welding process the joint is heated more in one place than another it will distort. (this is what happens with mig) another problem with mig is that the weld is harder than the surrounding (parent metal) so metal finishing it is difficult at best, it can be done as Johnny Arial showed but it is I feel a lot of work compared to dressing out soft gas welds that have caused very little distortion due to the even heat effected zone (the blue area around the weld) Below are some photos of a model A wing I repaired in this way.
Just got into this thread, we use .023 wire fitment is key. Never quench it. Start off every 2 " & just keep using the leap frog method. by the time you get back to the first spt it is cool & so on. Plug welds are the best way to go for inner parts, We even braze some seams. Like they say evey patch has its own mind. The Copper magnets fro Eastwood work great, as well as there clamps.
You absolutely CAN anneal steel sheet. How in the world can an obviously skilled metal man such as yourself not know that? It's not the same process as aluminum. Was that what you were alluding to? Not like aluminum, in that you don't do it the same way, not that you can't anneal steel. You are right though, that video of Jesse was of him shaping an aluminum bike tank.
I could be way off base but I am going to say it anyways.I knew the tank Jessie was working on was aluminum. He annealed the aluminum blank so he could shape the tank,I bet he annealed it a couple of times.He did not do it for welding. I anneal steel when I am trying to harden the piece. I am trying to control the heat,so it does not make any sense to me to add any additional heat before welding.
Yeah, maybe I took it the wrong way. Either way, you can anneal steel, just not using the burning soot trick, takes more heat than that. I also want to clarify that I'm not suggesting that anything needs to be annealed prior to welding (or after for that matter). The only reason I would anneal a sheet of anything, would be to take some work out of it (so to speak), so the shape could continue to be raised, while preventing it from splitting or cracking in the process. I guess you could relate this discussion to welding, albeit in an oblique sort of way, because a gas welded bead is more or less self annealing. By that, I mean it cools much slower than a TIG or MIG bead, so it ends up being a lot softer when all is said and done.
I still use gas. I have tried Mig & never could get the hang of it. Gas & an english shrinking hammer & dolly has been good for me since the early 70's.
Well I love a philosophical difference of opinion. Just last week I was repairing a 33 Packard gas tank cover panel. The sheetmetal was more like light gage plate, as in it was pretty thick. I had a piece of .050-something that was near enough the same thickness so I used it to gain a better finish alignment after welding. There's a raised feature in the sides (the areas of repair) so we wipped up a hardwood die of sorts and pressed that in. That's when the hardness of the said sheetmetal revealed itself to us and helped explain the increased difficulty we experienced. I decided that annealing it would save some time and used the soot method as a manner of showing my guys how it's done. I didn't make the metal red hot, I also didn't just burn the soot and frankly it took a lot more heat to burn it off that steel than it would have if it were aluminum. It was hot enough to scorch a piece of wood and we let it slow cool. Maybe the moon was right, maybe I held the right expression on my face, maybe the sun was shooting solar flares that day. The fact is both of the guys were intrigued by how much easier it was to shape that part for the repair. We TIG welded the panel on, and whether or not the annealing process had anything to do with the remainder of the finishing/grinding/hammering I won't raise my right hand to that. I will say that it turned out all but invisible. The weld was approx. 1/2" over from a 3/8 radius along the side and dropped 90deg at the rear and wrapped over a 1/8 hard wire on the end. I could not have shaped this part (both sides) to that level of quality without softening it up some. Did I get lucky? Well I'd just as soon be lucky sometimes. Also for the record I have no idea what the composition of the new metal was other than a nice clean piece of sheetmetal the right thickness. Coulda been HSLA, plain ol carbon sheet, simple mild steel. It worked and worked fast n easy...just the way we all like it.
I have found areas I torch shrink seem softer. I have to throw in with the steel does aneal group. Only trouble with steel is it's tougher to keep the heat even. Heat travels through aluminum fast, so the heat naturally spreads itself out better then steel. It is an interesting subject. Jeff
I am not saying you can not anneal steal but I don't understand why you would add heat( ranging from 760 to 910 degrees Celsius ) after you were ready to weld. I have never tried it to help shape a panel,I would have to try it to comment on it. Here is the definition From Wikipedia, the free encyclopedia Jump to: navigation, search <!-- start content -->Annealing, in metallurgy and materials science, is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness. It is a process that produces conditions by heating to above the re-crystallization temperature and maintaining a suitable temperature, and then cooling. Annealing is used to induce ductility, soften material, relieve internal stresses, refine the structure by making it homogeneous, and improve cold working properties. In the cases of copper, steel, silver, and brass this process is performed by substantially heating the material (generally until glowing) for a while and allowing it to cool slowly. In this fashion the metal is softened and prepared for further work such as shaping, stamping, or forming. I am not going to heat my patch panel until it glows
well for sheet metal thats on the car, patch panels, wheel wells, etc., ive done mig welding. if you have the ability to tig weld something thats not on the car i would go with that. whenever your welding sheet metal make sure you take your time with spot welds spaced out a little bit at a time and make sure you cool them down in between your welds with air. the last thing you want to do is warp a panel so just take your time and make sure to watch you rheat and you should be fine.
Doing it this way you do not get any warpage? I did a test panel that way and it warped really bad. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here goes...With out metal finishing the weld. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I tacked the panel in inch increments. What I noticed was even with just the tacks,the panel has already started warping. Next I started filling in between each tack.Skipping around and cooling the weld completely every inch of welding. What I noticed here,without re-stretching the haz,the panel is getting worse with every new section of weld. After I finished welding the panel,it was sure apparent this panel was in pretty bad shape. Sure glad that's not welded to my car. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Metal finishing the weld. I started off by tacking it the same way as I did the other panel.Except I ground down the proud of the weld of the tacks,flipped the panel over and re-stretched the haz of the weld on each tack. Now I filled in between each tack.Starting from the center and alternating sides until I reached the end of the panel. I finished each inch of weld the same as I finished the tacks. After getting the panel welded you sure can tell the difference between the two of them.
I would not try to anneal a panel after it's already formed. I'm sure you've come across some shapes that you have a hard time forming without cracking the material. Something with a lot of shape, where you're pulling a lot of shrink on the edges and raising a big crown in the center. If your panel has a lot of work in it to start with (like cold rolled), you are sometimes time and effort ahead to go ahead and anneal the panel before you start shaping. I've also seen guys work the panel hot, which is essentially the same thing, they're just annealing as they work. You see that a lot when working steel over form blocks with a lot of shape in them. Kent White is a big fan of hot working steel over forms and post dollies. If you were able to get the shape you needed without annealing, I see no point in doing so before you weld the panel in place. It's just that sometimes you need to make the metal move more than it really wants to at its current level of cold work. You can skip the whole annealing thing if you just start with Hot Rolled sheet. It's annealed from the get-go, 'cause all the rolling work is done while the steel is yellow hot. It's got no cold work in it, so it works a lot easier than Cold Rolled does. Gotta take the scale off it though, so there's some added work there. It'll probably never come up unless you're building panels with a LOT of crown in a small area.
"re-stretched the haz of the weld on each tack." How did you do this.. Us newbie welders need every detail explained like we are 5 year olds..
This method will result in a panel that's puckered and twisted all to hell, as Jhnarial has shown very well. If you don't deal with the shrink from the weld heat, regardless of how that heat was generated, you will end up with a panel that's all out of whack. As you can see from that picture he posted, you want to strike the heat affected zone (HAZ) of the weld (the discolored area around the tack or bead) with a good body hammer with a face size appropriate to the area you're working. This will be a stretching operation, so it is hammer on dolly, steel on steel. He's using the pick side of the head in that picture because the HAZ is so small. He doesn't want to stretch outside the HAZ if he can help it, so he's gone to as small a striking surface as he can. Using the small striking area also concentrates the blow, so it stretches faster, but you gotta go slow, or you could stretch too much in one place and make things worse. This sort of work is always a "creep up on it" kind of deal. You work a little, and then look and feel the panel and see which way you need to proceed. Never take big bites unless you are damned sure of what you're doing (like when you're blocking out a big crown, there's a lot of room to fix crap-ups in that situation, so you can wale away on the panel early to get the shape started quickly).
Sadly there's a few in the office PC and I'm outta there for a bit. I'd love to post a pic. "I would not try to anneal a panel after it's already formed." I didn't, I did it after I formed the 1st feature. And no I didn't hot form it either. I wanted it to form easier cold in order to get a spot on fit.
Actually the picture of the pick is a bad example of re-stretching. Take down the proud of the weld,then place your dolly directly behind the weld and give it a few taps on the top side.Only hit the blued area that surrounds your weld(haz).Check your progress with your hand as you go.
I understood what you were saying, I was more speaking to Jhnarial's post saying he wasn't going to heat his just finished patch panel cherry read before he welded it in. By "already formed", I meant totally done, not in-process. There are several instances where a fellow might need to anneal a panel (or a portion of one) in the middle of the forming process. If it's finished and you're satisfied with the shape, there's no reason to do an anneal before welding.
If you can control it, a flat nosed pick would stretch it out very quickly. A round nose or pointed pick will just make a mess of golf ball looking dimples. I should have specified. I don't MIG weld sheet metal, but it would seem to me like you'd want to try very hard not to hit the weld itself if you can help it. If you abuse them too much, MIG welds crack, right? The weld filler metal will split before it stretches. The rest is the same across the board, TIG, MIG, or Gas, but with TIG and Gas, you can planish the weld bead along with the HAZ, without worrying about it cracking.
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