Help with MIG job on sheet metal

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I am welding a new quarter panel on a '67 Mustang using a MIG with sheild gas doing a butt weld about five feet in length.I realy don't want to screw it up so can any body give me some help with the heat range and wire speed settings. I always have the most trouble with that and because it will be visible and I don't want to burn away my new fender and part of the car I could use some expert advice.Thanks in advance.
Reply:One thing for sure, whoever has to finish the panel should  get a say so in the cut/weld. You’re working on a  car that can be very valuable and deserves top workmanship.Do you know there are some  adhesives used for bonding panels that (I hate to say it) are recognized as superior to welding for some applications. I’m not kidding. Get some input from a body man knowledgeable in the most current repair techniques. Let’s see -  390-4v, top loader 4speed, 4:10 Detroit no-spin, no radio, manual steering, is that how they ordered it?
Reply:Originally Posted by jerseyjoeI am welding a new quarter panel on a '67 Mustang using a MIG with sheild gas doing a butt weld about five feet in length.I realy don't want to screw it up so can any body give me some help with the heat range and wire speed settings. I always have the most trouble with that and because it will be visible and I don't want to burn away my new fender and part of the car I could use some expert advice.Thanks in advance.
Reply:I recommend easy grind wire for your mig as well. It will produce a softer, easier to grind and work bead. Perfect for body work. Some complain that it produces more shrinkage though and is inferior for thick portions of body structure. It's worth a shot I'd say.
Reply:When I put a panel on I make sure the panel is flat and the butt weld is perfectly aligned, then I 'spot' weld the two together. Actually a short stich weld that looks like a pimple.  Go to the other side of the panel align and spot weld.  I jump around the panel and go for 'spot' welds 1inch apart.  Practice on scrap before you try your new panel, get it right there first. The metal seems to be 18ga or .045" thick. When you  have spot welds 1" apart go inbetween and spot weld again.  You get the idea.  If you do more than spot it sinks.  See what I mean on your scrap.  I use .023 wire gas sheilding and on my HTP 200  I use coarse heat setting 3 fine heat setting 1 wire speed 3.2 (it just happens to work out that way)  The way I set my mig is set the heat so you get good penetration on the panel then point at your scrap pull trigger and turn the wire speed until it sounds right.  It will sputter when it is too slow, then you will get a steady zzzzzzzzzzzz  On my machine it is NOT like bacon and eggs frying more like zzzzzzzzzzzzzz  Then it will start to stutter again and 'push off' when you get the wire too fast. (So you do not have to have .023 you can use .o35 wire just set the speed right for your machine.) Slow it back down till it is right a steady zzzzzzzzzzzzzzzz.  It will weld differently when the metal is heated up than when it is cold.  If you need to make the repair invisible then grind the weld.  I use 4 1/2 grinder and a right angle air grinder with sanding disks to get it smooth.  Sandblast and the repair becomes invisible.  It is hard to get it perfect with a mig  (but you can get it very good)  With a tig it is slower but you have more control.  What type of mig do you have?  Practice on scrap till you have a good idea what you are doing.  If you have to do floorpans do them first as they are not as visible and you will get better as you go along. It took me about a week of floor pans to get 'good' but I didn't have anyone to tell me how to go about it. Do not be afraid to stop and tap the panels back into alignment before you weld. It is damm near impossible after you weld them so get it right the first time.  Do not overlap it just leaves a place for water to collect and rust out your new panel.  When the weld sinks it can be covered with filler but I prefer a metal finish (no bondo)  How good are you with hammer and dolly?  Covell has a dvd on "Basic techniques for working with steel"  A little pricey at $40 but it shows you what can be done.  He makes it look easy.  There are only 4 things you can do with steel: cut, stretch, weld, shrink, everything else is a combination of those 4  (such as bend)  Hope this is a help.Thermal Arc 185 TigHTP 200 MigCraftsman O/A1942 Bridgeport Mill12 Ton Hyd PressConsew Walking Foot
Reply:spotDrivesector Hobart Handler 140Hobart Handler 180Ready Welder 2Hobart Air Force 400Airco Stinger 225Of all the things I've lost, I miss my mind the most."OZZY"
Reply:I would do it down hill. Sheetmetal, downhill with a mild steel wire, .035. Being a quarter panel and removable, no problem. Get the wire speed right by welding a similar piece of metal. Even a flux core would do it, but it will need some work to finish it.
Reply:Thanks for all the great replys. I borow my neighbors Snap On MIG welder to infrequently to remember what settings work best. It does spot, stitch and continuous welds. So far after about 3 years I welded in floors, cowel vents, drivers side quarter panel, inner & outer whl housings and various patches but never did a butt weld. The driver side qrtr-pnl was a full fender that slipped under the roof panel just as the factory did it and was easy to conseal but the pass side qrtr pnl is just a skin and has to be butt or lapp welded so it has to look good becuase it's on top of the body line from tail light to the door.Oh' and I'll be the one doing the finishing work after the welding.Good advice, I'll use the old qrt pnl to practice on.Any other advice is welcome.I'm curious about the glue technology but don't know a darn thing about it.