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  1. #11
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    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

  2. #12
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    Mar 2007
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    Oahu, Hawaii
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    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....
    I'm not late...
    I'm just on Hawaiian Time

  3. #13
    Join Date
    Aug 2006
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    near rochester NY
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    thanks sun i knida figured it had to do with haz.
    thanks for the help
    ......or..........
    hope i helped

    feel free to shoot me an e-mail direct i have time to chat. james@newyorkmetalart.com
    summer is here, plant a tree. if you don't have space or time to plant one sponsor some one else to plant one for you. a tree is an investment in our planet, help it out.
    JAMES

  4. #14
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    Mar 2007
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    [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.
    welding...its awsome

  5. #15
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    Mar 2007
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    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

  6. #16
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    Mar 2007
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    Yeh i knew that the mig was the most common these days of course cause most find it easier but didn't know about the brittleness of using o/a sheet metal. Sounds like im goin with a mig if i do decide on it
    welding...its awsome

  7. #17
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    near rochester NY
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    SundownIII
    i would love to meat an old timmer willing to take the time to show me how to lead in.
    any chance you got a pic of the lead roadster?? would love to see it. i always thought it would be cool to pick up a little car and tear it down to frame and see where it ends up when i'm done. what a great project.
    thanks for the help
    ......or..........
    hope i helped

    feel free to shoot me an e-mail direct i have time to chat. james@newyorkmetalart.com
    summer is here, plant a tree. if you don't have space or time to plant one sponsor some one else to plant one for you. a tree is an investment in our planet, help it out.
    JAMES

  8. #18
    Join Date
    Dec 2006
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    Wartburg,Tn
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    sounds like a cool project bring out the camera !!

    Inferno Forge

    Chris

  9. #19
    Join Date
    Dec 2005
    Location
    wisconsin
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    Quote Originally Posted by SundownIII View Post

    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
    By 1950's technology you must mean OA, TIG and MIG. Especially since TIG was created in the 20's MIG in the 30's and OA since about 1900. In all honesty the HSS panels that everyone is talking about are found only in structural areas of most modern cars. You will also find that the OEM usually doesnt allow welding of any kind on these areas. If there is any question contact your local OEM body shop/dealership, they have charts for each vehicle listing the approved repair methods for each part ( for newer vehicles). MIG still destroys the heat treat on the HSS panels, and in fact can have less fatigue resistance due to localized hardening of the base material. The Mig welds I have had the pleasure of working around were usually so hard that they cracked when planished out. Alas I personally feel that the introduction of MIG into the autobody world had to do more with the body shops bottom line, and less with any technical gain. Not to mention its easier and cheaper to get a guy to goober and bodo some panels together then to hire a real metalman.

    -Aaron

    P.S. the above information about welding methods and where HSS is used comes from 3 Ford engineers I work with.
    "Better Metalworking Through Research"

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  10. #20
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    makoman,

    Don't really disagree with anything you said. A mig in unskilled hands can also yield an unsatisfactory repair.

    Going back to my previous post I will restate, because the high strength steel has excellent tensile strength--about 40,000-120,000 psi compared to mild steel's 30,000psi--panel thickness could be reduced, resulting in considerable weight savings. The catch is that high-strength steel cannot be gas-welded or brazed. It will harden and crack. Because of it's unique grain structure, it must be arc-welded with a low-hydrogen stick electrode such as E-7014, or wire feed welded. Ford and Chrysler both recommend MIG welding. My source then goes on with about 10 reasons why.

    When I referred to 50's technology, I was referring to equipment which was "economically feasible" to have in a shop at that time. In my dad's shop you would have found an assortment of Harris and Victor O/A sets and an old Linde AC arc welder. You're right tig and wire feed welding have been with us for a long time. TIG was "refined" as a result of demands placed on the Defense industry during WWII. It wasn't until the 80's that MIG became "economically feasible" to be found in your local "body shop".

    I agree 110% with your comment about "bottom line" and the skill level of today's metalworkers.

    BTW, I, in no shape or form, consider myself an "expert" in this field but have been around body repair just about my whole life. My uncle (referred to in previous post) was a hard hat diver/welder for the Navy during WWII. That guy was a magician/artist when it came to working metal. He'd roll over in his grave today seeing what some folks call "bodywork".

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