Well i know, the best way to weld sheetmetal would be gas welding. My problem is i have a major warpage problem even if i weld point after point so take a look at the pics . Mayx someone can help me. My goal would be to get is so good that there is no need for bondo or lead after my weldings. Well this is a far way to go. Here you can see before and after pics the done pic is after one hour of straightening
stick and gas will always warp the plate. get your self a mig. maybe add a spot welder head adapter to the buy . spot it about a inch apart and keep working your way around till your done. cool each spot with a damp rag while working this keeps the heat down and lower the warpage. i do 4 spots,cool, do 4 more, on and on till it's done.
I think you would want to hammer weld it if you could thats suppose to help with warpage. weld alittle bit then take, with the welds still red hot, Hammer and Dolly it flat. This is suppose to help on the shrinkage. and just do alittle at a time and Alignments key.this is still done with gas welding.
How are you doing it? Keep it to short welds and hammer them a little while they are still glowing. Let the metal cool down too. It takes a little practice and a ton of pacients. Dont listen to the last guy either, MIG is one of the crappiest welds out there for sheet metal, it gives you a hard almost impossable to work weld
okay the metal is Mig welded. And yes i have the problem that the welding seam is so f***ing hard you cant beat this flat. as it looks there is no way araound gas welding . The whole rest i am exactly done how you guys say it have to be done. Except the wet raqg trick.
1. dont be in a hurry. a little bit here- then move 180 degress and alittle more, then go take a leak and let the metal cool or 2. use the wet rag deal- and still go slow or 3. pick up some heat sink material- and go slow
Weld a little, move to a different spot. Trick - use welding magnets on each side of the weld. Holds the metal in place, helps prevent warpage, and absorbs some heat. Cool with wet rag. Also, heat tip of welding rod away from metal first, then begin welding. Hammer & dolly while its still red. have welded quarters on this way with very little filler required. Takes practice, and good dexterity.
if your gas welding you need a gap at least half the width of the welding filler rod.1/16in.gap would use 1/8 in.rod.the gap allows the metal to expand and contract with out buckling and gives a flatter easier to hammer weld.use the smallest tip you have and keep the flame just big enough to melt the rod in about a second or two when placed in front of flames white cone.tack the runs not the corners and dont cool to fast as this will cause beer canning that would require more heating and shrinking of the panel after your done closing all the seams up.weld a 1/2in. then hammer ,move to another side,repeat untill finished.take a piece of scrap and try what i said first with a tight fit and then with the gap and you will see what happens and the difference in the finished weld.they built all the world war 2 planes with gas torches and we won and they were mostly done by women.if they could do it anyone can.
I was always told that cooling the metal with a wet rag while welding hardens the metal, weld, etc... Is this true?
rapid cooling hardens the weld and heat affected zone.it also shrinks the panel,thats how shrinking discs work.if you put a small dent in metal and heat it up then rapidly cool it it will usually pop the dent out.you tube has how to remove dent from car,check it out a guy pulls a dent from a door with a hair drier and a can of computer keyboard cleaner.
tack weld 2 spots them stretch the weld by hammering on dolly. the heat from welding shrinks the metal which has to be stretched back out. tack 2 more spots on either side of your first 2 tacs then stretch by hammering on dolly. dont let the panel get to hot. you should be able to touch it and not feel discomfort. repeat this process until you have the panel tacked 1" a part. go slow. dont let the panel distort. when you tack a panel that has distorted you lock the distortion in. the panel then gets much harder to straighten out. once you have the panel tacked every 1 " weld in the un- welded spots. every time you fill in the 1" spot use your hammer and dolly to straighten it out. any time you weld in a spot that has been distorted form the previous weld it will lock in the distortion. then it will make the panel harder to straighten out. next use a slapper made from a leaf spring and a dolly to straighten out low spots on the panel. next use a shrinking disc and run it over the panel getting the high spots hot. cool the hot panel with a wet rag. that will lower (shrink) the high spots. use some guide coat and a body file to highlight the highs and lows just like when using bondo. you are only filing off the paint and not the metal. your tools must have polished faces. any imperfections on the faces of your tools will transfer to your panel. you will need to repeat the slapper and shrink disc process many times to get the panel straight. it takes a long time to do. experts who know what they are doing say it takes 1 hour per foot just to weld in a panel without distortion. they use a tig process for the cleanest results. gas welding will produce nice results if you can do it without putting to much heat to the panel. you can mig it by putting tack weld over tack weld to weld over the entire seam, also the weld is harder to flaten out. you can get a panel straight enough to use some high build primer and have it ready for paint. fit your panel with no gap using gas or tig process. use a very small gap using the mig process. practice on some scrap until you understand the process instead of messing up your project. their is a learning curve to this. personally i get the panel welded in the way i mentioned and slap and shrink until the panel is real close. then i use body filler for the last little bit. the cars i work on dont warrent the time it takes to get the panel perfect. now if i was working on a 41 willys i might rethink that. tom
Tomkat's got it right, but don't expect to be able to weld and hammer a panel, esp. a flat panel, perfectly enough not to need bondo. That comes with years of experience. Sometimes you get lucky, but it is a skill that requires lots of practice, a good eye and good coordination to achieve! You "can" hammer and dolly MIG welds, to a degree. Either try to work REAL fast, or do a few welds, grind down the weld about 80-90% of the way, and then try hammering it. If you do this method, be sure you are getting 100% penetration on your welds, or they will crack....some may crack any way, just reweld.
I just tac mine good and then just weld it all the way but I do use a tig welder I also let it cool on its own then hammer the welds to raise the metal back up.
The done pic is after one hour of straightening. After one hour of straightening does it look better? If not straighten it for another hour. You are not doing anything really wrong, metal warps when you heat it, then you have to ding it back in to shape. If you can limit the flex great if not just hammer it back, the trick is going to be learning more the craft of hammering and straightening and learning to enjoy just that part of the process. You will find that you actually start to enjoy hammering the metal back to shape. It's an art, it requires it's due diligence. Have fun.
Thick mig wire, .035 or bigger works great for gas welding if you fit the panel tight. you still need a little gap .040 or so. Don't let anyone fool you every type of welding causes shrinkage, which in turn causes warpage. So you need to stretch it back out to correct the warpage, Gas welding just leaves the best condition to be able to stretch the bead.
With gas and 20 gauge... 1. Tack every 1-1.5" 2. Stop frequently to planish Or... 3. Use a TIG (along with 1 and 2). The heat is more localized and less likely to cause widespread expansion
The descriptions of the craftsmanship required to do patch panels worries me. I have a '40 Ford cpe. with rusted out panels behind the doors adjacent to the running boards. The rust out runs from behind the doors to just ahead of the rear fenders about 1-1/2" high,due to leaking quarter windows. There is good metal to weld to on all 4 edges around the bad part. I ordered some patch panels from Dennis Carpenter that were disappointing junk only suitable for use as filler metal. They were just bent from flat stock with no curvature at all ! I ordered another set from Bob Drake which are very good and true to the old curve of the body. I have zero experience with sheet metal welding on body panels. I bought a MIG welder thinking that I could probably do it OK. After reading the preceding posts I'm doubting my abilities. I'm getting kind of old (67) and lack the good eyesight and manual dexterity of my youth. I'm really an engine guy with no body work experience and would regret screwing up this body. Do you guys think I should attempt it or find a local guy(north of Dallas) to come to my shop?
I'v read most of this thread, and tomcat is right on, tig is the best weld, and there is alot of complaint about how hard mig is to grind. But if that is all you have there is wire available called easy grind that I find works quit well, and I have not seen it mentioned.
Are you really using mig, or flux? sometimes people call fluxcore mig, but it is much hotter. might make a difference.
listen to the others, dont mig weld it. it creates too hard of a weld. you need to creep up on it. like the others have said, spot/tack weld then jump around to opposite sides to "pull" the panel towards the heat source. this gives you a centering effect. then slowly fill in between the spots/tacks with weld. give it time to cool. never wet rag it. it causes the metal to harden too fast and become more brittle with more prone to crack around the welds because it shrinks too fast. just my 2cents.
tomkatz description of the correct procedure is PERFECT!! Follow that and get some experience and you will do fine. Remember TIG or gas weld you want zero to very small gap, as you add filler metal because the gap is to large, you increase the amount of shrinkage and will need more hammer on dolly work. Correct weld procedure is the first step in having a flat panel proper hammer and dolly work followed by filling is the other step. Rex
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