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Warped Metal

Discussion in 'The Hokey Ass Message Board' started by crusinthelowlife, Sep 2, 2011.

  1. crusinthelowlife
    Joined: Jul 10, 2011
    Posts: 6

    crusinthelowlife
    Member
    from Oregon

    THis is question for all you metal fabricators out there. I just got done welding the hood to my 50' chevy together and jumped around with my welds as to not warp the hood but I end up warping it a bit any suggestions on how to un warp it?:confused:
     
  2. KrisKustomPaint
    Joined: Apr 20, 2007
    Posts: 1,107

    KrisKustomPaint
    Member

    the weld zone must be stretched. hammer on dolly.
     
  3. crusinthelowlife
    Joined: Jul 10, 2011
    Posts: 6

    crusinthelowlife
    Member
    from Oregon

    do mean hammer and dolly on the weld it self or around the weld?
     
  4. crusinthelowlife
    Joined: Jul 10, 2011
    Posts: 6

    crusinthelowlife
    Member
    from Oregon

    seriously some more imput would be great
     

  5. wristpin
    Joined: Aug 31, 2009
    Posts: 48

    wristpin
    Member

    you could always use the heat and shrink method.
     
  6. How was it welded ?

    Mig?
    Tig?
    OxyA ?
     
  7. oldgoaly
    Joined: Oct 22, 2004
    Posts: 562

    oldgoaly
    Member

    welding causes the metal to shrink, like Kris said hammer and dollie to stretch the weld back to shape. Go slow if you stretch it too much you will need to shrink it again.
     
  8. hotrod40coupe
    Joined: Apr 8, 2007
    Posts: 2,562

    hotrod40coupe
    Member

    Try using a shrinking disk.
     
  9. crusinthelowlife
    Joined: Jul 10, 2011
    Posts: 6

    crusinthelowlife
    Member
    from Oregon

    I mig welded it and its kinda of hard to stretch the weld because it was a two piece hood and there is a seam on the underside of the hood where the two piece's come together
     
  10. BuilderRhys
    Joined: Sep 16, 2007
    Posts: 128

    BuilderRhys
    Member

    Hammer on Dolly, that`s my approach. It works well for me but I hammer or stetch the weld as I go. I put in a small 1/8" to 1/4" tack and hit it with the hammer on dolly before moving onto creating the next tack. It is only a light hit, just enough to slightly flatten the tack, thus streching it. On the long reach to the back side you may need an extra hand with the dolly or the looooooong reach planishing hammer. Regards, Rhys.
     

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  11. oldgoaly
    Joined: Oct 22, 2004
    Posts: 562

    oldgoaly
    Member

    OK, get yourself a chunk of 2" or 3" square bar stock, cut a slot how ever you can that is deeper and just a little wider than the ridge. This is your new dollie, your going to need to round over the sharp edges of your dollie it will also need to be polished 300-400 grit should make it smooth enough not to transfer marks.
     
  12. crusinthelowlife
    Joined: Jul 10, 2011
    Posts: 6

    crusinthelowlife
    Member
    from Oregon

    thanks guys for the input i got a buddy with a shrinking disk so i'll try that and oldgoaly that dolly idea is good i'll be trying it also
     
  13. metalshapes
    Joined: Nov 18, 2002
    Posts: 10,716

    metalshapes
    Tech Editor

    I'm guessing a '50 hood is slit down the middle and attached together with a flange, like the Chevy Truck hoods of the same period.


    When you weld, you get shrinkage.
    If you are are carefull you can can controll it better, but you still get shrinkage.

    So what happened here, is that you have two strips of metal running the length of the hood that are perpendicular to the outside skin.
    And you shrunk one edge of those strips.

    That is your warp...

    And you cant hammer and dolly it right, because the flanges are in the way.

    You could try to heat shrink next to the weld, but thats going to be tricky and might not work.

    Or you could try to carefully cut the flange away from the inside.
    And then carefully try to work the metal after the flange is gone.

    Or start over by welding a strip ( at least 4" wide ) down the middle of the hood.

    Here is one I did on a Chevy Truck.

    http://www.jalopyjournal.com/forum/showthread.php?t=104467&highlight=chevy+truck+hood
     
    Last edited: Sep 3, 2011
  14. oj
    Joined: Jul 27, 2008
    Posts: 6,263

    oj
    Member

    Do not take a shrinking disc to the hood - it is shrunk enough already. As metalshaper said, cut the flange off on the inside so you get a dolly tight against the backside of the weld and then hammer like crazy, i presume you mig'd it and that'll make it that much harder. You need to stretch the metal. I wouldn't weld any more to it - metalshaper is a pro and knows how to deal with deformetal but you are figureing it out as you go and you will get into deep serious shit if you try to do any more welding.
    Good luck, oj
     
  15. toolman1967
    Joined: Mar 13, 2008
    Posts: 441

    toolman1967
    Member

  16. crusinthelowlife
    Joined: Jul 10, 2011
    Posts: 6

    crusinthelowlife
    Member
    from Oregon

    Thanks metalshapper that sounds like a good idea, the hood is fully welded up should that be a problem I didnt notice the warpage untill I was 95% done with it so I just finished. Also should I grind the weld down and cut the flange and then hammer them?
     
  17. metalshapes
    Joined: Nov 18, 2002
    Posts: 10,716

    metalshapes
    Tech Editor

    From what I remember of these Chevy hoods is that the radius from the skin into the flange is pretty big.

    So the weld would be pretty low in the crease, and there wouldnt be much weld stick out over the surface.
    ( depending on how you welded it, too )

    So I'd just start by grinding away the flange on the backside.
    Taking care not to weaken the weld too much, and you'll also have to be carefull not to scar the backside of the hood.
    Making thin spots that would be a problem later.

    A cut off wheel would work best, but you can do it with a angle grinder if you have to.

    So I'd concentrate on the back side for now, and when the basic shape is right, clean up the outside.


    ( As long as your weld is reasonably smooth.)
     
  18. blinddaddykarno
    Joined: Feb 5, 2008
    Posts: 121

    blinddaddykarno
    Member

    No, don't heat and shrink, it's warped because it did shrink when he welded it!! You need to strech out the heat affected area by hammer on dolly.
     

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