Hey dudes I got a 72 Charger restore project, I need to buy a mig welder anyone know what make and size I should buy for sheet metal. Also what is the best wire size. Do I need gas or just electric. New memeber.

 

Best welder would be a 220 miller full size model. Pricey though. Gas not gasless medium size tank.

Wire size would be 24 with gas.

HOWEVER that is for someone experienced with welding and wants to do a good job.

For someone who is new to welding, while easier with a good unit, a small 110 gasless unit is good to practice on first.

A small patch type of fix a gasless is good enough. I would recommend using 30mill goldshield or blueshield wire though.

Very few people can properly weld with a mig welder even with years of experience. They weld on a setting too low and the pentration sucks big time. This is the leading cause of weld failing.

A good weld will actually leave a small bump on the other side of the weld. It's almost flat really but is still a bump. The other side where it is welded is also almost flat and requires very little grinding. Spot welding is the hardest.

I have welded for years with various migs both good and bad quality machines. I can weld on metal that is very rusty or clean and get good welds on each. My spot welds don't usually require any grinding at all and never pop.

Here is a few tricks for you.

If you use gas to weld with the manuals say 10 pounds pressure set to 15 cause the metal gives off oxygen from the rust as you weld.

Practice on scrap tin first, preferably rusty tin. Welding on good clean tin is easy. Welding on rusty unclean surfaces is much harder but if you can the feel for it welding on good tin is a snap.

Whatever you feel the setting for heat on your welder is good for tin go one setting higher. There is two reasons. One if flows a heck of a lot better and two it pentrates.

The greatest trick to welding is to maintain a puddle of a sort. If you can see a puddle your actually welding if there is just sparks your only laying wire on top and not really welding.

Mig welding tin you only weld for about a 1/2 in at a time and move a foot away and do the same there. I prefer to use an air gun to blow on the welds after I weld. It cools them a bit faster along with the tin around it and also cleans any flux from the spot weld at the same time. Another advantage to blowing with air gun is that the area around the weld is usually clean of any paint, primer, or rust.

You WILL burn a hole through. It is not avoidable. The metal you are welding will be thin in one spot for various reasons and you will burn through. To fill a hole that is small stop welding till the glow fades away touch the trigger and get it hot again with some wire. Stop let cool repeat. If nessary you can drag pass over areas that are thin to build them up with spots of wire first before getting them hot with weld.

A flatten piece of copper pipe works great to get behind spots where your tin edges dont quite meet up. Make one pass over the copper remove the copper and make a proper pass to weld.

Small tiny strips of tin or even a coat hanger can be used to help fill in areas while you weld.

Someone will no doubt scream that get your area clean before welding. That is a rookie mistake. You can actually do more damage to the metal cleaning it before welding. You should however sand blast a weld after you have finished all your welding and grinding.

An area to be welded should be free of paint, and serious rust. You should NOT grind an area to be welded. If the area is questionable you can make a quick pass with a sandblaster from a few feet away. most of the time a braided wire wheel on the end of a grinder is more than good enough to weld.

If you are spot welding both pieces need to be clean and painted. IF you use weld thru primer apply it wet and start to weld while it is wet. If it's dry its spits like hell.
I prefer to use a high zinc paint which takes longer to dry. Rust paints are high zinc they do flash as you weld so be prepared to put out the flash fire. Most of the time it does it once and that's it. I also drill my spot welds on the car with a shallow ground 1/4 drill bit. Seems to work better. I put two vise grips on either side of the spot weld drill it so that only the first is cut while the second is just marked then weld.

From experience unless it says VISE GRIP on the clamp its junk. They make quite the variety and most of mine are full of welding spits. I have also made some other tools to hold my pieces or clamp them. Be prepared to make your own tools as you go along. Keeping a stock of various metal odds and ends will come in handy.

On cars there is rules, not quite laws, regarding mig welding. One of which is that the tin must overlap 1/8 of an inch. They do not like you butt welding on a car at all. There is merit to the idea as there is more surface area for the weld but the finished product can be lacking. A butt weld has a greater tendancy to crack though.

Do NOT grind welds smooth. It's best to grind them to be just showing a line on either side of the weld and it is somewhat level with the metal. Grinding too much weakens the weld a lot.

If you are patching the quarter panel or large section of a car you WILL stress the tin quite a bit. Warping will probably occur as the two pieces of metal will pull towards each other as you weld. I would suggest that after a car has had serious welding done on it to leave sit in the sun for a few days to destress the metal. I use black paint on the areas to seal the metal and leave sit in the sun or keep the area around the car fairly warm with a heat lamp which I turn off and on every other hour. With the heat lamp the whole panel heats up and then cools.

good luck sorry for rambling on.

 

Ive used a bunch and currently run a Lincoln 180C. With or without gas. This is a 220 model that has nice adjustability for both thin and thick stuff. It will get you threw all aspects of a project IMO.

 

We run a Miller 110 unit at work with 35 flux wire at work. I does good work for thinner sheet metal. You can even run solid wire and gas with it.

 

I run a Miller 135 110v unit and, although it isn’t boxing frames any time soon, it can tackle most the jobs I have to chuck at it. I run flux but it can run gas, too.

Flux is hotter and a tad more beefy, but not nearly as clean.

Gas is clean and easier, but doesn’t have quite the penetration at the same settings.

I love my Miller.

 

If you want to run a gas MIG but need deeper penetration, look at using C25 shield gas. It's 25% carbon dioxide and 75% argon. It will give slightly deeper penetration and shouldbe more than enough for most auto work. One warning though, don't use it for aluminum or stainless steel as the CO2 will screw that up mightily. You must use straight aron or even helium for aluminum.

 

I'm using a miller 110v with co2. Its what I got lying around. I have used my cousins miller 220v with co2 and argon mix. It worked a lot better.