Car panel rust repairs - TIG any good?

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I have a few rust repairs to do in some vehicle panels, I have the options of OA, mig or TIG.OA and brazing gives lots of distortion and is what I had to do years ago. I've tried the Mig (with CO2) with reasonable success but wonder how practical the TIG might be. Can't think of any reasons it shouldn't work apart from the price of shielding gas. Hoping to butt weld replacement patches, trying to keep things neat and rust free for the future. All light gauge Japanese panels.Has any one got any experience or suggestions about TIG for this, please?"One of the things we have to be thankful for is that we don't get as much government as we pay for." (Charles Kettering)Mitch 180 (NZ)Lincoln SAM-400-220 + ?-400 Fordson Major + 2 x Tractapac Humber 80 + Procut 40 PlasmaMiller Spectrum 375
Reply:I have done a good number of fairly quick and dirty jobs. For sure mig is quicker and easier, but there can be a lot of grinding involved to cut the beads down after.Tig can be neater, but the the skill and time involved is substantial, also fitment of the patches needs to be a lot beter than with mig that can easily fill and bridge gaps. Myself I would think it difficult to have the patches cut exact enough to allow decent tig welds, the gaps need to be nearly water tight on thin materials. Flanging the edges of the hole and setting the patch in would make for easier welding, but does make places for water to settle and rust through from the inside.You might find argon CO2 blend does better with the mig on thin stuff like sheet metal.Last edited by Timberwolf; 07-30-2008 at 10:03 AM.
Reply:MIG, using a shielding gas of 75% Argon\25% carbon dioxide is the preferred method for autobody patch panels.  100% Co2 promotes deep penetration...something you want to avoid on thin sheet metal.  I would also recommend 'Twenty Gauge' brand cored welding wire.  Part #TGE2....030"  It produces wide, flat beads, so less grinding.  Another plus for the MIG process is that you can use a weld-through coating rich in zinc to abide rust in inaccessible areas.TIG, at least for me, heats up the metal too much because the process is slow going, (It would be OK for tack welds)  just like OA.WeldingWeb forum--now more sophomoric banter than anything else!
Reply:Which is best, depends on what you're trying to achieve really. Oxy fuel can be the way to go sometimes but ignoring it for now,...For a quick patch up to keep the thing alive a little longer then MIG definately. Even for restoration work MIG works well but TIG comes into it's own if the repair is going to be  metal finished for minimal to no plastic filler- the welding/panel beating takes longer than if MIG were used but the welds are easily planished so time is saved in post weld clean up and prep for paint. That's assuming of course that you're comfortable welding 20/22g and know your way around hammers and dolliesThis is one of a pair of decklid scoops i made for a 67 beetle after a little planishing- TIG welded with 0.8mm MIG wire for filler. I was a touch heavy with the filler this time but there was still much less grinding/sanding/filling required than if MIG were usedI have a front wing from a nissan 200zx that needs a small patch letting in awaiting my attention. If it'd help i can document the repair as it's pretty simple one
Reply:I would find tig tough, but..... Some can like the fine job above.  For me it would be SP100, .023 wire and C/25.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by 69 chevyMIG, using a shielding gas of 75% Argon25% carbon dioxide is the preferred method for autobody patch panels.  100% Co2 promotes deep penetration...something you want to avoid on thin sheet metal.  I would also recommend 'Twenty Gauge' brand cored welding wire.  Part #TGE2....030"  It produces wide, flat beads, so less grinding.  Another plus for the MIG process is that you can use a weld-through coating rich in zinc to abide rust in inaccessible areas.TIG, at least for me, heats up the metal too much because the process is slow going, (It would be OK for tack welds)  just like OA.
Reply:Originally Posted by hotrodderWhich is best, depends on what you're trying to achieve really. Oxy fuel can be the way to go sometimes but ignoring it for now,...For a quick patch up to keep the thing alive a little longer then MIG definately. Even for restoration work MIG works well but TIG comes into it's own if the repair is going to be  metal finished for minimal to no plastic filler- the welding/panel beating takes longer than if MIG were used but the welds are easily planished so time is saved in post weld clean up and prep for paint. That's assuming of course that you're comfortable welding 20/22g and know your way around hammers and dolliesThis is one of a pair of decklid scoops i made for a 67 beetle after a little planishing- TIG welded with 0.8mm MIG wire for filler. I was a touch heavy with the filler this time but there was still much less grinding/sanding/filling required than if MIG were usedhotrodder I have a front wing from a nissan 200zx that needs a small patch letting in awaiting my attention. If it'd help i can document the repair as it's pretty simple one
Reply:Timberwolf and David R thanks for your replies.I'll probably use the Mig for the majority of the repairs but there are a couple of areas where there's a sort of concave compound area needing repair and if I mig, then it would be nigh on impossible to dress the weld. One of them is a sort of stand out cab mount on a Mazda Bongo (where do they get these names from?) it's at the rear of the cab and is plainly visible, or at least is in an area they'll target, so I was thinking of a repair with as little as possible weld showing and looking "clean" for inspection.David, I expect I'll be using .6mm wire, which is about the .023 size. I normally use CO2 and getting some CO2?Argon mix might take a bit of figuring yet. Machine is an Elektra Beckum160 Et 230v single phase, 160 amp 60% duty cycle.How do you guys get charged for cylinders? Here, for a small 10 pound bottle, it's about $140 a year to lease and then you pay for the gas each time. On current prices, after 2-1/2 years, you'd have paid for a new cylinder but then you've got to get them checked and also wait while they fill them 2-5 days. Whereas with a lease or rental bottle, it's a straight swap. Someone told me recently that the gas suppliers here make more money from rentals than they do on the gas. They are really cylinder rental companies, not gas companies.Anyway, here's a shot of a Bongo. 1800cc, 109ci and four wheel drive, including duals on the rear. Wait until it gets a cherry picker on the back of it! That's how a few of them arrived from Japan.and, now the cherry picker. See some other rust repairs. About 6m or 20 foot reach."One of the things we have to be thankful for is that we don't get as much government as we pay for." (Charles Kettering)Mitch 180 (NZ)Lincoln SAM-400-220 + ?-400 Fordson Major + 2 x Tractapac Humber 80 + Procut 40 PlasmaMiller Spectrum 375
Reply:Originally Posted by Tractapac Is the "'Twenty Gauge' brand cored welding wire.  Part #TGE2....030" a flux cored wire and so doesn't need a shielding gas...?
Reply:Tractapac,Probably be next week before i get to it, small chance i may get to look at it tomorrow. I'll start a new thread in pictures/projects forum
Reply:Originally Posted by hotrodderTractapac,Probably be next week before i get to it, small chance i may get to look at it tomorrow. I'll start a new thread in pictures/projects forum
Reply:Originally Posted by David RI would find tig tough, but..... Some can like the fine job above.  For me it would be SP100, .023 wire and C/25.David
Reply:Tractapac, My bad, it's a 200SX. Not my cup of tea but at least it's not wrong wheel driveMade a start on it late this afternoon,... http://weldingweb.com/vbb/showthread.php?t=23036Last edited by hotrodder; 08-01-2008 at 06:37 PM.