Weld It Yourself

By Glenn Goodspeed (January, 1998)

I didn't bother to ask how much it would cost to have new floor panels welded into my classic car. I've had enough experience with body shops to know it would be very expensive. Instead, I began looking for information about welding and welding equipment. I thought if the tools were not too expensive or difficult to use, I'd purchase them and do my own welding.

All the sales literature I read said it was easy, and everything I checked out of the library said welding required practice and proper safety precautions.

The library books explained the different kinds of welding and what they are used for. The two basic kinds of welding are gas and electric arc. Gas welding is done by focusing a burning mixture of gases, usually oxygen and acetylene, on the work, usually two pieces of steel. Arc welding uses electric current to heat the work. The intense heat melts some of the metal from each work piece. The molten metal mixes, and the two pieces are joined together. After cooling, the metal is as strong as a single piece.

During welding, metal is added to the work via a rod or a wire. For auto body work, a wire welder is most convenient. The wire is thin enough that the heat required to melt it will not burn holes in sheet metal. Two kinds of wire may be used. One has a flux core that leaves a chemical coating on the finished work and must be removed before painting. The other kind of wire is solid metal, which must be used with metal-inert gas (MIG) equipment.

All the books agreed that auto body welding is best done with MIG equipment. This is arc welding with the addition of an inert gas to shield the work from exposure to the atmosphere. If molten metal is exposed to the air, it absorbs enough impurities to make the weld weak and to make the welding process very difficult. MIG welding has an advantage over flux-core welding in that the finished weld is very clean and requires little preparation for painting.

O.K., said I, all I need now is a MIG welder. I studied the welding equipment offerings in various catalogs, including Sears, Eastwood, J.C. Whitney, and Northern, and read all the ads for equipment in Hemmings Motor News.

Then I went down to the local welding equipment supplier while on my lunch break from work. I felt pretty strange in my shirt and tie, waiting at the counter with a bunch of professional welders covered in sweat and dirt. The guy behind the counter took me seriously enough, though, showed me their selection of MIG equipment, and gave me a brochure to study.

Since the local supplier's cheapest welder was way too expensive for me, I decided to order from the Sears catalog. I tend to buy brand-name equipment when I don't know much about it, and Sears offered a small Lincoln Electric arc welder within my means. I also purchased an accessory kit to turn it into a MIG welder. Of course, the next Eastwood catalog had a ready-made Lincoln MIG welder for less than what I paid, and so did Home Depot, where I picked up welding gloves, wire brushes and a chipping hammer.

Oh, well, I was ready to start, except for one detail. The mail order kit did not include a bottle of inert gas. I went to the local welding shop and bought a small gas bottle and had it filled with a 75%-25% mixture of argon and CO2.

A word here about gas bottles. The 20-cubic-foot bottle I bought had to be refilled five times to complete the work on my floor panels. Each refill cost another $20. Total cost for bottle and refills was $185. Funny thing about refills. They are the same price for a 60-cubic-foot bottle as they are for the 20-cubic-foot bottle. That means I could have bought the larger bottle and done just as much work for the same price and only made one trip to the welding supply instead of six.

The guy at the welding supply first mentioned this on my fifth refill trip. He said I was "beating a path," and I might want to consider a larger bottle. By then I was tired of having to get the thing refilled, and I was planning to start this discussion myself. I was almost finished with the floor panels, but there were still some rusty spots here and there to be fixed on the body. I knew I would not be doing as much welding in the future, so I compromised on a 40-cubic-foot bottle, but if I had to do it all over again, I would go for the 60-cubic-foot size.

Anyway, I was about to describe the welding itself. It's great! I don't know why, but I get a real kick out of joining pieces of metal together so that they're as strong as one piece. It does take practice. I studied my books and the videotape included with the welder before trying it out. I practiced on some scrap metal, and then progressed to fixing patio furniture. Finally, as a useful practice project, I fabricated a caddy for the inert gas bottle.

After all that, the floor panels were not too difficult. But I'm still learning. Welding is a true craft. The more you do it and think about doing it, the better -- and faster -- you get. The first floor panel took eight hours to weld in. The second took three hours. Lately I've been cutting out small rusted areas with a cutting wheel in my grinder and then welding in patches of carefully shaped sheet metal. I bought a couple of large flat sheets of steel from J.C. Whitney for patches.

It was obvious the first time I used the hand-held face shield included with the welder that it was not going to be satisfactory. Apart from the fact that you have to use one hand to keep it in front of your face, the lens in it was so dark I couldn't see what I was doing. Next time I went to the welding supply, I asked about helmets and lenses. The guy told me that lenses come in various gradations, and he showed me the impressive selection of helmets they sold with replaceable lenses. He recommended one with a large lens, and I said o.k. I told him I wanted the lightest lens that would not endanger my eyes, and he removed the #12 lens and replaced it with a #8, which is quite a bit lighter. Later I was very glad he had recommended the large lens, because it makes it much easier to see at different angles in close quarters.

While I was at the welding shop, I made sure to buy a welder's hat. I had seen the professional welders wearing them, and I thought they looked cool. Besides, they come in a dazzling array of colors and patterns. I got one with a pattern composed of multiple freeform shapes in bright primary colors. I'm sure one of the secretaries snickered when I tried it on backwards. The brim is supposed to be worn in back to protect the welder's neck. I'm glad I bought the hat. Not only does it look cool, it also is the perfect cushion for the tight plastic band that holds the helmet on my head.

Something to consider before you buy welding equipment is what you're going to plug it into. There are several small arc welders available that use 110-volt household current, but most of them require a 20-amp circuit. Open your breaker box and see if the circuit breaker for the area where you plan to weld has a 20-amp breaker assigned to it. If not, you may need to consult an electrician to provide adequate power for your welder.

There is so much available information about welding technique in the library that I won't get into it here. The best sources for auto body welding information are textbooks about all auto body repairs and refinishing. Check out a few books and find one that's easy to read and contains information about the type of welding you want to do.