Welding Tips
by Tom Carrington and Herb
"Has anybody done "stick welding" on VW's? If yes what current would you use?"
Tom Carrington writes:
It is difficult for me to "stick-weld" on thin guage sheet metal. I prefer Oxy-Acetlyene welding over the stick. I usually end up burning holes right through the metal. Even better is MIG (Metal Inert Gas) welding for the thin stuff. A MIG welding tip is surrounded by a gas that displaces oxygen, and helps cool the surrounding metal. Argon is a common gas when welding with MIG.
"I've found this welder at Orchard Supply for $200. It goes up to 225 Amps. It is a single phase 220 V AC. I can hook it up to my dryer outlet. Would this do the job?"
Well, it is plenty big! Overkill for sheet metal, though!!! Does it have AC as well as DC output? DC welding will deposit more metal from the rod while the torch is "lit", as opposed to AC, which will burn deeper into the metal. BTW, I have plugged my welder into the dryer outlet, but please keep in mind that the welder will come with a 50-amp plug on it, and the dryer is either 25 or 35 amps. You will need to make and adapter for it. The breaker did pop whenever I tried to make long welds.
Here's a quick rule of thumb on amperage and metal thickness. Use the same amperage as the thickness of the metal. For example, to weld 1/4" steel, use 250 amps. (1/4"=.250", get it?) For 1/8 inch, use 125 amps...and so on. On 18-20 ga sheet metal, you will need to use the lowest amperage that you can still get the torch to maintain an arc. Maybe 60 amps on a thin rod.
Also, choose the type of rod carefully! Not only diameter (thinner rods are for welding at low amps), but also the properties. For example, a #6013 rod will deposit a lot of filler material, but a #6018 will cut into the surface.
"If with stick welding you can easily melt the metal, then how about gas welding?"
Takes some practice, but that is the way the body guys did it for years before the MIG.
About 7 years ago, I took a welding class at a local vocational technical program run by the county government. Classes were at night, three nights a week. It was for six weeks, and cost less than $200. We were taught flame, stick, MIG and Heli-arc welding in that class. That $200 has been paid for many times over! Before embarking on your project, I would recommend the same!
Herb writes:
I concur, don't buy a stick welder!
You need to find a wire welder. The good ones (Lincoln, Miller) will cost you about $700 complete but are well worth it if you have the money. Otherwise, you should rent a small wire welder (MIG). Mine is the Lincoln SP-100 which is a 115v machine so it plugs in to any 15-20 amp fused outlet. It puts out much more power than is necessary for sheet metal work.
I have tried to weld sheet metal with a stick and it is nearly impossible. The wire welder, on the other hand, does a very nice job. You will need some practice or instruction to make good looking welds.
When welding long seams put a spot at the beginning and end and then in the middle and then successively halve the distance between welds. That way the metal doesn't get hot and you don't have sheet metal warpage.
I use 0.030" mild steel wire with an argon(75%)/CO2 mixture. It works quite well. I have rebuilt the whole left side of my '74 including making new jack supports. I used a piece of metal that runs laterally between the supports and up to the side support. As I recall the piece was about 18"x48".
I put in a new seat attachment plate which I manufactured from some 3/32" steel. I think it is a lot stronger than the original.
In addition I have welded in many smaller pieces where the metal is rusted. You will need a sabre saw and a good number of blades to cut out the "old" metal. I have a very small aircompressor (3/4HP) with a small tank and I find that I can use an air gun to cut the sheet metal if I am not in a hurry. It has made the job pretty easy when the sabre saw couldn't be used.
You need to take care to clean both sides of the joint to get good welds. Also, you will need to figure out how to "clamp" the pieces together prior to welding. I use a combination of clamps, Vise-Grips and pop rivets.
You will need a 4" or 4 1/2" offset grinder to smooth up the welds prior to covering with Bondo.
I have been very satisfied with the work. It is fun to see the old van get back to as good or better than new condition. It may be a tad heavier as 18 gauge is thicker than the original metal.
