Need some help.

  1. shaan New Member

    Messages:
    5
    Location:
    Netherlands
    I'm having some troubles welding new sheet metal into a car.

    While spot welding it penetrates and sticks to the new metal but it does not penetrate the existing metal.

    The existing metal of the car is +-1,5mm
    The new metal is also +-1,5mm
    The area is around 20cm long and 4cm high.

    The existing metal is cleaned, to shinny bright silver metal.
    The ground is placed next to the welding area on cleaned metal,
    The MIG weld wire is flux core and the machine is from Deca.

    Im new to welding and i have tried turning the wire speed up and down as well as the voltage. This resulted only in burn troughs and sputtering.

    I hope this is enough information, and that somebody is able to help me why it is not able to penetrate en stick to the car (existing metal).

    Greetz Shaan
     
  2. Lazurus

    Lazurus Member

    Messages:
    590
    Location:
    Norfolk uk
    Some pictures of the metal and your setting may help.
     
  3. shaan New Member

    Messages:
    5
    Location:
    Netherlands
    At this moment the car is back on its wheels so im not able to take good pictures.

    the steel is now fixed at three points, and it looks real bad, at all other points the weld will not bound with the car.

    The metal was clean but now a yellowish color is over it after all the welding tries.
     
    • IMG_20190710_171040.jpg
  4. 500e

    500e Always buy fire insurance a flood is hard to start

    Messages:
    3,920
    Location:
    Somerset UK
    Are you sure it is not Galvanised the yellow suggests it is\ was
     
  5. eddie49 Member

    Before starting this job, did you practice MIG welding at your workbench?
    The best way to gain this new skill would be to just lay down simple straight weld beads on new clean 2 - 3mm steel, then some simple lap and butt and fillet joints. You can post pictures on here for comment and advice. After perfecting that, move on to the harder tasks like thinner metal, old dirty/rusty metal, and the tough job of welding in awkward positions under a car. Even skilled welders can find that difficult.
    Are you using an automatic, self-darkening helmet? That is definitely to be recommended.
     
  6. shaan New Member

    Messages:
    5
    Location:
    Netherlands
    Im not sure, a magnet will stick to both the new and the cars metal. But the new metal is pulling stronger.

    To Eddie.
    Yes I tried and just the spots weld was oké, the mess on the car started when it burns out and only sticks to the side. If that makes sense?
     
  7. eddie49 Member

    Generally the best way to fit patches to cars is by butt welding, where the patch is an exact fit into the hole cut into the rusty part. That is the ideal way, it gives a flat surface with no overlaps that could trap water and restart the rust. However, I have found that if you are overlapping, it is easier if the new clean, solid, and probably thicker patch is under the original. That way you get less burn-through at the edge of the hole.
    As for the yellow colour, that may be flux residue from the gasless wire.
     
  8. MoreWellie Member

    Messages:
    1,015
    Location:
    Bedfordshire, UK
    if that coating on the original metal was something like waxoyl then you have to really clean the metal before it will weld at all nicely

    it also looks to me as if your spots could do with the trigger holding for slightly longer. I usually start the weld on the joint but biased slightly to the new metal and then loop it on to old metal once the puddle is established
     
  9. gaz1

    gaz1 Forum Supporter

    Messages:
    8,442
    Location:
    westyorkshire
    I can tell you that you havent cleaned the car metal properly enough just from that pic the part you are welding too must be clean

    on another note welding with gasless is harder as it appears very bright when welding compared to normal gas you need a higher setting but be aware it can and will burn through

    ignore this
     
    slim_boy_fat likes this.
  10. shaan New Member

    Messages:
    5
    Location:
    Netherlands
    Thank you for all the reactions, I'm gonna clean it again the best I can. I did it with a flat disk and steel wire brushes on a drill.

    And this Saturday I will try again.

    Can copper welding wire be a better fit to this application? As it seems to me the new metal gets hot enough but the existing metal of the car does not.
     
  11. eddie49 Member

    It is not copper wire, the copper colour is a very thin plating on solid steel welding wire. Your current set-up is for flux-cored wire. To use solid, you would need to reverse polarity on the MIG torch and the return lead, and provide a supply of inert shielding gas ( CO2 or Argon mix ). You may also need a new wirefeed roller and torch tip.
    MIG welding with gas is usually easier and better than gasless, but obtaining the gas is often difficult and expensive. However, switching to solid wire with gas will not solve the issues highlighted in this thread. You need to cut back to perfectly sound steel, scrape off the underseal and paint ( with a blade - wire brushes just smear it ), leaving 1cm of bright clean metal on both sides, then put the patch into place.
     
  12. shaan New Member

    Messages:
    5
    Location:
    Netherlands
    Oke thx

    I don't get it any cleaner than this, it is a different spot on the car.
    so I'm curious if it will work now
     
    • IMG_20190712_111727.jpg
  13. gaz1

    gaz1 Forum Supporter

    Messages:
    8,442
    Location:
    westyorkshire
    i can tell you now thats still not clean enough you can still see white on the metal a die grinder is sometimes much better to get right in those ackward areas
     
  14. eddie49 Member

    For a correct and lasting repair, identify where the rust ends and the remaining solid metal begins. Mark straight lines and cut all the rusty metal away on those lines. A simple straight outline makes shaping the patch easier. Transfer the shape to your new metal using a cardboard template.
    Your latest picture shows a jagged hole, through more than one layer of steel, with rusty, pock-marked, weakened edges. When you weld that, the thinned metal will blow through, the contamination will enter the weld pool and weaken it, and the rough edges will trap water and re-start the rust, causing the patch to fall off next year.
     
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