Correcting distortion - thoughts please

  1. RTFM

    RTFM Member

    Messages:
    32
    Location:
    UK, Shrewsbury
    Hello all,

    so I’ve finished the main build of the welding bench, just need to add some hooks and hangers.

    I noticed the top has concaved fairly evenly with peak deflection of 8mm. There are three supports, one each side and one through the middle, these are 25x25x5 angle
    I was planning on doing a wedge weld (as indicated) and then using some 40mm box and g-clamps to encourage correction and limit any over correction. If the first in the middle doesn’t fix it, I’ll do one either side and so on.
    Two questions
    • is that the right idea ?
    • should I do all three supports one at a time or all together? I’d need to buy more clamps to do them all together.
     
    • A21DD07E-F2E9-4CF5-BC00-1FB6B1E2E36F.jpeg
    • 06DC3B93-7BC5-4EEC-97B5-BDE017A0263B.jpeg
  2. gaz1

    gaz1 Forum Supporter

    Messages:
    9,171
    Location:
    westyorkshire
    if memory is correct you would be welding the wrong side to correct that

    you always weld opposite side to where its bowed too
     
  3. RTFM

    RTFM Member

    Messages:
    32
    Location:
    UK, Shrewsbury
    oh? All the weldings been done on the top - howz it bowed down and not up. Weird :laughing:
     
  4. optima21 Forum Supporter

    Messages:
    2,705
    Location:
    halifax, England

    because when the weld cools down it contracts so the top is shorter than the bottom
     
  5. colnerov

    colnerov Member

    Messages:
    3,265
    Location:
    Nr Gatwick UK
    Because as the top surface has cooled it has contracted.

    Snap!
     
  6. angellonewolf

    angellonewolf Member

    Messages:
    4,497
    Location:
    bristol england
    can you not q clamp with a bit of wood it and pull it back inline abit ruff
     
  7. RTFM

    RTFM Member

    Messages:
    32
    Location:
    UK, Shrewsbury
    That’s what I thought, so putting a bead or wedge on the bottom should correct it
     
  8. RTFM

    RTFM Member

    Messages:
    32
    Location:
    UK, Shrewsbury
    I’ve clamped it flat, it just springs back when I release the clamps.

    suppose I could clamp and then blow torch it. Let it cool in the clamps and then release
     
  9. gaz1

    gaz1 Forum Supporter

    Messages:
    9,171
    Location:
    westyorkshire
    you need to push it past straight to cancel the spring back so it goes straight again
     
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  10. RTFM

    RTFM Member

    Messages:
    32
    Location:
    UK, Shrewsbury
    Gotch-ya, so I need to put some packers in at the ends
     
  11. angellonewolf

    angellonewolf Member

    Messages:
    4,497
    Location:
    bristol england
    15794428549264178846208949338152.jpg this will give you more space to over bend it so when released go back straight

    if any one can rotate the pic for me thanks
     
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  12. RTFM

    RTFM Member

    Messages:
    32
    Location:
    UK, Shrewsbury

    awsome, thank you.
     
  13. frank horton

    frank horton V twins are great but 4"s rule.........

    Messages:
    1,463
    Location:
    Soon 2 B Crete
    sorry but shoud have boled it down with counter sunk cap screws....mines an 8x4x10mm sheet on 60x60x3 legs n supports....10mm stainless c/s/caps hold it down...
     
  14. RTFM

    RTFM Member

    Messages:
    32
    Location:
    UK, Shrewsbury

    Good idea that

    building the bench as my first project, it’s full of reminders for me when I actually build stuff to use ;)

    welding trolleys next........
     
  15. Bit over the top for what your doing but same principle

     
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  16. Yamhon Member

    Messages:
    969
    Location:
    Earth
    Your diagram reminds me of one technique which might work for you. I'd still use a jack or piece of timber to encourage the table back into the desired shape, but if you cut out a small v where you've indicated and then run a bead down it, it'll shrink that side down and bring the ends in.
     
    RTFM likes this.
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