Oxy Acetylene Welding Autobodies?

[wrenchtech]

You can forget using OA on autobodies. Somewheres about the early-mid '70s the alloys used were changed. You might be able to fuse it together, but it will be very brittle. At some point the insurance companies told the bodyshops, if they did not have a mig welder on hand, that they would not be paid. They got tired of cars falling apart after being welded with OA. (Dad was in the autobody business for 60+ years.)

Will

I'm looking for further input on this question. It seems strange to me that you could weld chrome moly 4130 or 304 stainless (with flux) with OA, but not the alloys used in auto bodies. Can anyone explain just what alloys are used and what the difficulties might be. I want to weld some patch panels on a mid-80's Toyota pickup bed (bedside). -- Matt

[weld_13]

I for one second that because I would like to know if I will have to get in touch with some friends so I can borrow a mig welder for workin on a possible jeep for my mom or if I coudl get away with o/a

[Bert]

wow, that's a shock! those that fell apart must have been a guy that didn't know what he was doing! My grandfather had "Wong's Auto Body" since 1941, took over by my uncle, then died out from too much competition...
Didn't know it had to be mig or nothing...Weld13, if you know how to do it right, I can't see the insurance company complaining if they don't know! You might want to visit some body shops or ask/call up the votech teacher and ask him...

[dabar39]

O/A on auto body

You can o/a on the outer body panels, it was the uni body and structural supports that could not be done with out a mig. Dave

[weld_13]

Either way it will be worked out because know of a couple of people locally with migs and once you do a coulpe of favors and stuff they always give back in fact one complemented after I miged up something on his machine said it was mine to borrow if I ever needed it or anything else. My brother is also an expert on o/a welding don't know how he does it so well but I think I will start gettin some more practice on it so I can show him up on that cause he can't even use a mig very well. I have only done it about once and hes worked a whole summer job of o/a welding on aluminum and steel. The jeep would be an 80's model cj7 but am still looking for one in good shape at a decent price

[weld_13]

You can o/a on the outer body panels, it was the uni body and structural supports that could not be done with out a mig. Dave

Alright thanks Dave

[wrenchtech]

You can o/a on the outer body panels, it was the uni body and structural supports that could not be done with out a mig. Dave

The bed I'm working on has metal sides that measure at 17 gauge. My patches will most likely be 16 gauge. I'll be working with a #2 tip (23A90 type) on a Harris torch. Any ideas on what type and diameter of filler rod I should use? -- Matt

[weld_13]

Just a thought make shure you look at what a local welding store gives you because someone we know went to a store bought what he thought was a aluiminum rod for o/a and then found out once he gave it to my brother and he found out the hard way it was for steel

[fun4now]

i would think just standerd steel filler would be fine. try to stay close to the same size with the filler as your base metal.

[fun4now]

so why no O/A on the unibody?? too much haz??

[SundownIII]

The automakers(all) in the 70's, in an effort to reduce weight, and thereby improve fuel economy, changed their sheet metal alloys. The new alloys are, in fact, thinner, but stronger than the alloys which were previously used. It was found that O/A welding created a large HAZ which was subject to cracking and therefore the shift to MIG.

By using stitch welds and moving around the panel being welded the bodyman can control the heat much better that was possible with O/A.

In actuality, more brazing was used in body repair, than was O/A "welding".

O/A welding requires a much higher skill level to employ properly than does MIG. In an unskilled hand, an O/A torch can do a lot of "damage" to today's body materials.

Things have changed a lot in body repair in the last 50 years. My dad opened his first body shop in 1946 and ran shops til he retired about 10 years ago. You can bet if today's technology had been available 50 years ago, the shops would have used it. I still remember mixing calcium chloride in a big hopper to produce acetylene for the O/A. There was no bondo then. Lead and spoons were the name of the game for fairing.

Why would anyone want to use 1950 technology when there are better tools available? Don't own a mig. Borrow one, rent one, but get one.

Just my .02

[Bert]

Sundown,
thanks for the info! Unfortunately, I was never interested in doing body work growing up. Now I kind of wish I had learned enough to do my own truck. Oh well....

[fun4now]

thanks sun i knida figured it had to do with haz.

[weld_13]

[quote=SundownIII;14031Why would anyone want to use 1950 technology when there are better tools available? Don't own a mig. Borrow one, rent one, but get one.

Just my .02[/quote]

Because I thought that with the right skill it would be easier to form the metal. Even if do work on it with a mig will still be using an o/a torch for some heating and forming.

[SundownIII]

Weld_13,

Don't get me wrong, every welder (or wantabe) should have O/A at his disposal and be versed in it's safe operation.

What I'm saying is that "times have changed". If you went into today's modern "auto body repair spe******t" shop (aka-body shop) and asked 90% of the technicians how they would "shrink" metal with O/A, they wouldn't have a clue what you were talking about.

I'm betting you'd find more technicians versed in the use of a pop-rivet gun, than you would find proficient in the use of O/A.

Along the same lines, as little as 20 years ago, most body metal was cut using either hand shears or pneumatic shears. Heavier material was cut with a torch. Plasma is now the tool of choice and a good one at that.

I think the biggest thing that led to the "demise" (if you want to call it that) of O/A in body repair, was when shops went away from the use of lead and moved to plastic body fillers (bondo). Watching an "old timer" shape lead with a torch and a spoon was like watching an artist at work. Heck, I've probably still got a couple hundred pounds of "lead sticks" in the shed. I never got proficient at it (age 6-10) but my uncle was one of the best. He and my dad built a 2 seat "sports car" using a '53 Merc frame. Pretty "far out" when it was built (won numerous awards). Car must have had 500# of lead in it. (I'm sure the fuel mileage sucked by today's standards).

Nuff said.

Later