Which welding works best for panels?

danliveshere

danliveshere

Well-known member
Guys I can mig weld ok(self taught). I have oxy-acetylene, but never oxy welded only used for cutting. I bought a Tig last year, but still haven't even turned it on and still haven't organised a gas bottle.
OK my question is who finds what method of welding our panels works best? I believe oxy is nice to file and little distortion but can you guys say which you prefer and why? Also if you like Tig welding, what do you use for filler rods? I really should hand this over to a pro to get my body back together but I'm going to have to perservere and do it "with a little help from my friends"!!Most of my fenders, hood etc are nice and straight, but I have to replace floors, inner rear guards, bottom of cowl, rockers etc so I have alot of welding to do. Thanks for your assistance.
 
TIG'ing ain't like MIG'ing. You need to be running puddles with the Oxy-Acetylene while playing bass drum then you will be ready to TIG. I suggest that you get some big hunks of brass to hold behind your welds as a heat sink and use your MIG with small wire and gas to put your pieces together. Might look for that special wire that makes the softer bead for better grinding afterwards.
 
36tbird said:
TIG'ing ain't like MIG'ing. You need to be running puddles with the Oxy-Acetylene while playing bass drum then you will be ready to TIG. I suggest that you get some big hunks of brass to hold behind your welds as a heat sink and use your MIG with small wire and gas to put your pieces together. Might look for that special wire that makes the softer bead for better grinding afterwards.
Click to expand...

Here's some info on Easy grind MIG wire.
http://www.ask.com/web?l=dis&o=13992&qsrc=2873&q=easy grind mig wire
 
If you're doing sheet metal, tig or oxyweld gives you better control. Both take a lot of practice (skill). It is no big deal to weld the sheetmetal together, mig/tig/oxy whatever, the skill part is to do it without warping the metal all to hell and gone. I suggest you get some 18ga and start practicing, the tig is an easy machine to learn - hard to master, but to do sheet metal it would be the easiest thing to learn on. I'll cut to the chase here, what you will have to do is learn to weld FAST. Lots of people are going to go on and on about heat sinks and all manner of elaborate methods of backing the weld to minimize the effect of heat - i have done/tried/invented many of them - the problem with all of that is it takes a certain amount of heat to melt steel, so what good is a heat sink? The best, cleanest weld with minimal distortion is done with speed, do not linger. I crank up the heat and run right down the seam, no filler rod (i use a small piece and let it run adjacent to the the torch and if a gap opens i'll touch it quick, the rod acts more as a heat control) the whole process is so quick that i don't actually see the puddle and i take it on faith that it is welding. This method produces the smallest of HAZ and the HAZ is what creates the distortion.
 
I like MIG for floor boards etc because it's quick and easy. Go fast as oj said and it will reduce the grinding required.
I prefer TIG for fenders and body panel repair as it produces the least distortion. Also the best for heat control at the tip.
Oxy hammer welding works well on fenders/panels where you can get a dolly behind piece being welded. While this creates the most heat distortion you can remove the distortion with hammer and dolly.
Practice makes perfect!?!?
Good luck with your project!
 
Hey Dan-
TIG welding the heavier gage metal parts is pretty straightforward, so I'll only talk about butt welding the light gauge panels (patch panels).
I figure I must have welded about 15-20 liner feet altogether in panel welding my '32 cabriolet with good success. This included replacing one quarter panel, the usual patch panels and both wheel wells. I used .045" diameter ER70S-6 rod with the welder set at 25 amps and a 1/16 inch electrode. After tacking in the entire joint at about 2 inch intervals, I would go back and weld 1/2 inch at a time, skipping around to keep the heat down in any area. What worked well for me was to lay the rod right down in the joint and keep it in contact with the panel metal. The panel acted as a heat sink and kept that small rod from melting back away from the puddle. It also gives you a very uniform size bead. Try it. You may like it too. Good luck with your project!! Bill
 
I do this for a living, Bill and Dan, the problem with how Bill did it - no disrespect here believe me, his method is what is considered 'approved and correct' ie: tack and then skip around to minimize the heat buildup. Heres' the problem - the heat is behind you so skipping ahead cannot minimize the heat 6" behind you, what does happen is that each time you start the fresh weld you have to linger at that spot until you are up to temp, then you run a couple inches and lift the pedal then skip ahead and repeat. Each time you start and stop you are focusing heat at that particular spot, the metal reacts by shrinking greater than the surrounding area. If you look at the HAZ (heat affected zone, the blueish area on each side of teh weld) it will look like a bunch of catepillars walking in a row. At each juncture between the catapillars is where you start/stop the skip around welding and if you run your finger over taht spot you will feel where the metal is pinched because it has shrunk to a greater degree than the areas surrounding it.
I could talk about this for a month and not explain everything, i bet whole books have been written on this very subject. The most successful butt weld is done in one fell swoop starting at one end straight to teh other at a high speed with the heat set at a high value so that if you slowed down you'd burn thru quickly.
 
In my younger years, 1950's, I wanted to be a body man. All of the repairs to body metal was done with a oxy/Acetylene, either using a mild steel rod or brazing.
Many "real craftsman" body men I know will only use gas welding because gas welding puts carbon back into the weld, thereby not making the weld brittle like wire feeds do.
The older bodies have heavier gauge steel so gas welding works well, new bodies are more like gum wrappers so the wire feed welders work better.
The man that does my body repair can butt weld panels together using a gas welder, the weld looks like a pencil line after he hot hammers the welds, no fillers required.
 
Ford evolved there welding teqniques right along with or even sometimes well ahead of the industry. It depends on the year of manufacture of each model as to the machines and techniques that were utilized. Most things were spot welded unless it was impractical. Cars as old as the Model As were mostly riveted.
 
I keep thinking about learning the oa technique. I am right in the middle of doing a patch panel right now and was interupted while welding and i thought it would be a good enough illustration so that you can see both the tacks and welded seam.
The tacks are large, the weld meant to be done in a single pass but you can see where i had to stop and add a touch of filler. After tacking i stretched each tack with hammer on dolly. After welding i'll have to grind the tacks and fuss a little but this should finish out with a skim coat if any at all.
I need to get another shop camera, but you can get the idea.
 

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I didn't hear any of you mention the use of panel clamp/spacers whiich hold the panels in alignment and gap them about 0.020-0.030" apart to allow for penetration and shrinkage. I agree, in theory, with oj's idea of hot and fast - that's how much automated welding is done, but the fit-up has to be properly engineered for that style of welding. But sticking with the MIG-tacking and back-stepping to weld the previously tacked area is easiest and best in most cases. Most of us are not doing high-zoot '32 roadsters to take to the AMBR show....Bob L
 
I agree with fordy nine. Mig welding by mig tacking and back stepping to weld the previously tacked area is easiest. Always a good fit and very little warpage. I have mig welded for a living for over 30 years. The biggest advantage that it has over everything else is its small heat zone that it creates. Using wet rags to cool, it's heat zone can be even smaller. With a smaller heat zone, there is less warpage. To fill in missing metal, mig welding is quick. With a brass block as a backing to weld against, holes and seams are quickly filled.
 
If you have no tig experience that panel is not where you should go.Tig is fairly easy once you have had some seat time but it does have a steep learning curve.The machine will help you lots if it has some extras like a foot pedal low amperage settings like 25 amps and down hi freq start.A good torch some 1/16" electrodes 2% lanthinated er70s6 or s2. 045" filler rod will get you going.Knowledge of weld results tungsten grinding gas cup sizes ect.All come into play.A buddy with tig experience would be a great asset.This info is to help you not make make some errors in welding choices.Most body shops use mig all day long.
Nuff said my2¢

Ronnie
 
Wow, seems I have opened a can o worms. About 15 years ago I found a 35 front fender that had heaps of rusted edges but was otherwise very straight. I had it sandblasted and undercoated , and set about cutting pieces of sheet metal and shaped them to fit the holes that I had cut out. This was purely an exercise in practise , I didn't have a clue what I was doing. I only had an arc welder using the smallest rods I could buy and the lowest amps. Most of the repairs went fairly well, considering I was green. I still have that fender, it needs a couple of my repairs to be cut back out and redone but I saved it. Ok back to the future, as most replies above say practise that's where I may start. Learn some basics oxy/acty and tig and see which I prefer.... or at least I may find 1 easier over the other. I'll also research an easy to grind mig welding wire, as I like mig already. All ideas on this subject much appreciated, Dan.
 
I also forgot to mention in my 1st post that all of this work I have to do is for 2 cars. I don't really want the first car to be the PRACTISE car!!!!
 
If you are an experienced gas welder, TIG is very easy to pick up. If you don't have experience in either, pick one ans focus on it until you nave made some real progress, then try the other process. If you don't want to devote such a large block of time to learn TIG, then stick with MIG - it does anything you need for bodywork to medium gauge plate plus it is much faster too......Bob L
 
Guys I've just ordered a silicone/bronze mig wire. It's very expensive compared to standard mild steel wire. they say it can be used with the tig as well and i can use the same argoshield gas that I have in the mig. It will be here next week, I'll let you know how it goes.
 
danliveshere said:
Guys I've just ordered a silicone/bronze mig wire. It's very expensive compared to standard mild steel wire. they say it can be used with the tig as well and i can use the same argoshield gas that I have in the mig. It will be here next week, I'll let you know how it goes.
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You require straight argon for tig welding steel with silicone bronze.You need an inert gas for tig.Argon co2 is not inert and doesn't produce a clean weld with tig..It is actually a tig braze application where the base metal is not molten.
You should get a second opinion about mig gas with tig.Mig rod with tig yes. Mig mix gas won't weld for you with tig.If you are using the mig welder then yes the gas will work.Silicone bronze works well for body work nearly as strong as steel and not like brass it is easy to have paint adhere to fine choice requires less heat also.I've used silicone bronze lots fun to use with tig.

Ronnie
 
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Ronnie are you saying I can still use the sil/bronze mig wire with the tig as long as I use argon gas only? If I have enough success with the mig I won't worry about learning other techniques, I'll have enough to worry about getting my gaps and joins all nice and square to weld nice. Dan.
 
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