I've put together this page to try and answer some of the questions I hear regarding what is the best type of welding equipment for a hobby restorer to get. No right or wrong answers, only my personal opinions and preferences. Each method has it's strengths and weaknesses.
If welding is just a task, then hire a professional. It will save you time, dollars, and perhaps some aggravation in the long run.
On the other hand, if you want to expand your skills and to learn and do it yourself, look into availability of adult education classes in your area. Then invest in good quality equipment (notice I did not say 'the most expensive').
If you decide to buy arc welding equipment, also plan on investing $150-300 in a mid-to-high end Speedglas electronic autodarkening lens helmet. This will shorten your learning curve considerably, provide more reliable eye protection, and help you become a better weldor.
I'm going to make an assumption about the typical restoration project and say that it will need some sheet metal patch panels, repair of some sheetmetal tears, and filling of a bunch of surplus holes in the firewall, dash rail, and cowl.
In addition, you will find a lot of little welding projects to do on the car and around the house. Also a 'flame' to heat and loosen various nuts, bolts, shackles, etc. will likely be needed.
TIG Welders
If you want to learn to do first class welding, then buy a TIG welder and learn how to use it. There is no substitute for practice. Books and videos are great for information, but they won't make a weldor out of you. TIGs used to be very expensive, but quality low cost TIGs are now available for about $1600-1800 out-the-door and ready to weld.
Though the cost of TIG is considerably more than a MIG or oxy-acetylene, it is a very versatile piece of equipment which has very high resale/residual value, even when it is ten years old. Not true for MIG or gas.
TIG stands for Tungsten Inert Gas. It is also known as GTAW, gas tungsten arc welding. The welder has a 'torch' with a tungsten electrode. An electric arc is drawn between the tungsten and the workpiece. This arc energy is precisely controlled by the weldor using a foot pedal or a slider switch on the torch handle.
The arc energy melts a puddle on the workpiece, and additional welding rod (filler) is added to the puddle. That's the manual dexterity part! While the arc is drawn, the molten puddle is flushed with argon or helium or other inert gas. This prevents oxidation and contamination in the weld and helps stabilize the arc. The gas is delivered through the torch also.
I primarily use my 1985 Miller Maxstar 90. It is a 115 volt 90 amp constant current DC inverter, which means it is small and lightweight, and can weld paper thin up to about 3/16 steel with very precise heat and puddle control, but it cannot weld aluminum. This is fine for me; I don't own anything aluminum!
I also have a Maxstar 152 which is a similar unit except it is 150 amps, 240 volt, and can also stick weld (though I almost never do). Both units have a high frequency arc starter and do not require scratch starting. This is especially useful to a beginner because it helps keep the tungsten electrode from becoming contaminated as often.
If you prefer Lincoln over Miller, you can buy a Lincoln Invertec V160-T Constant Current DC TIG minus the torch, gas, and regulator for about $1800 which will do everything mine does, is dual voltage, and goes up to about 90 amps.
The primary advantages of TIG are the precise control of all aspects of the weld, the lowest heat input to the workpiece of any welding process besides laser, and a very malleable resulting weld.
The primary disadvantages of TIG are initial equipment cost, the fear/mystique of TIG, and speed of welding.
TIG welding is like knitting by hand, MIG welding (Metal Inert Gas, explained below) is like stitching with a sewing machine. This should not be a problem on Model A's since it is unlikely you are going to be laying down miles of weld, or have to have all the welding done by quitting time today.
Another advantage of TIG is that you can use the electrode, which is called a torch, to heat up things like rusted nuts and seized bolts, all without a flame. TIG is the safest to use from a fire safety point of view since there are no sparks, sizzling spatter, acrid smoke, or open flame.
You can TIG weld at your kitchen table wearing a white shirt and tie, no lie. I've given a lunch time 'demo' at the welding store in a white shirt and tie to help sell a street rodder on the joys of TIG.
Another very important advantage of TIG over MIG is the very minimal metal finishing required after welding. TIG only deposits the filler you add, and you have total control of that. Say good-by to grinding and filing!
MIG Welders
If TIG is cost prohibitive, then you can make do with a MIG, even a 110 volt Lincoln SP100 which is what I also have. Again, it puts out about 90 amps which is plenty for sheetmetal work.
The cost of MIG is low, the welding speed is fast, the ease of use is high, and it is light and portable.
The disadvantage is that it is better suited for repairing bicycles and barbeques as opposed to sheetmetal restoration work.
MIG stands for Metal Inert Gas. It is also known as GMAW, gas metal arc welding. The welder has a spool of filler wire, and the torch/gun has a trigger which turns on the arc energy at the selected power level, and feeds wire out the gun nozzle at the selected speed.
The arc is drawn between the end of the wire filler and the workpiece. As the wire is fed, it melts and deposits onto the workpiece.
While the arc is drawn, the molten puddle is flushed with argon CO2 mix or other inert gas. This prevents oxidation and contamination in the weld and helps stabilize the arc. The gas is delivered through the gun nozzle also. This process is easy to perform crudely, and more difficult to perform elegantly due to the nature of the control of the weld parameters.
MIG puts down considerable weld metal by design, and those welds are much harder than gas or TIG welds. This means more grinding (a lot), and welds which can't be worked or hammered particularly well.
Also, if you get a small MIG like the SP100, get the bottle of 75% argon and 25% CO2, and use 0.023 inch wire on sheet metal.
Do Not get cheap and buy the fluxcore wire version MIG welders from Lowes or Home Depot! If it doesn't use a bottle of argon or argon mix, then you don't want it!
Stick Welders
Regarding stick welders and 'buzz boxes', forget it, don't bother. There's not much use for them when restoring an antique car, but they are great on the farm for welding up chisel points (by the way, a 240 volt TIG can also stick weld if you really have to have that capability).
About the only place I find a stick welder sometimes useful is for arc welding cast iron. Having said that, I use my Dillon gas torch, Tiger flux, and cast iron rod to weld cast iron. You can also TIG weld cast iron using 99% nickel rod. I have had better results that way than with arc welding cast iron with a eutectic rod.
Oxy-Acetylene Welders
An oxy-acetylene torch set is handy to have for all sorts of general heating and cutting uses, but there is an inherent safety danger with open flames, with acetylene which is highly explosive, and with oxygen which feeds a fire like nobody's business. It also takes a certain skill to control the puddle in order to flame weld sheetmetal well with minimal warpage.
If cutting sheet metal is needed, then use a manual, electric, or pneumatic hand operated shear or nibbler, or invest in a plasma cutter. An oxy-acetylene torch is a very poor choice for accurately cutting sheet metal.
I have used Victor torches in the past, which I have since sold. I now use a Henrob (Dillon) torch for cast iron and all my general purpose uses for heating things up, and I also use a Smiths Little (jewelers) Torch when I need to gas weld sheetmetal.
My best advice for welding sheet metal is still: Go straight to TIG! The same manual dexterity skills are required for both TIG and oxy-acetylene. If you can do one, then you can do the other.