best nut for captive nut

  1. John_d1974 Member

    Messages:
    31
    Location:
    Fife
    is there a best nut to weld when creating a captive nut?

    im using BZP and im trying to weld it on to mild steel, im using a sealey mighty mig 150 and getting poor results, it is on but its more of a spot weld here and there and look like ****.

    ive used various power settings and cleaned both the nut and bar to try and help

    as mentioned is is on and not coming off but is there a better nut to use?
     
  2. 8ob

    8ob Forum Supporter

    Messages:
    6,112
    Location:
    moscow on thames
    Self coloured square nuts.

    [​IMG]
     
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  3. outofthefire

    outofthefire Member

    Messages:
    2,336
    Leeds
    I personally use what evers at hand, but I prefer proper nuts to those square ones I prefer a few more threads.
     
  4. tom2207 Member

    Messages:
    2,033
    Location:
    uk northern ireland
    gods ,, never ... flange nuts , those square nuts are tragic even when not welded in , best left for spouting bolts that farmers put in land rover floors
     
  5. Ruffian Member

    Messages:
    2,491
    Location:
    Devon UK
    Usually make my own with abit of solid bar.

    That way can have plenty of material
    Circa 20mm for m8 etc.
     
  6. zx9

    zx9 Member

    Messages:
    4,110
    Location:
    South East London
    Good point, the OP did not say how big the captive nuts are to be, but as said if you can make your own there will be no problems with plumes of zinc from the burnt off BZP.
     
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  7. Paul.

    Paul. Moderator Staff Member

    Messages:
    6,573
    Location:
    Northampton. UK
    Self colour hexagon flange nuts are good for welding, you only need to weld on the flange not the hex, less heat needed and less chance of shrinking the nut and having to tap it out, get non serrated ones if you can.
     
  8. John_d1974 Member

    Messages:
    31
    Location:
    Fife
    i did think about that, would need to buy a tap and dye

    @zx9 its a m10
     
  9. zx9

    zx9 Member

    Messages:
    4,110
    Location:
    South East London
    Just a tap and something to hold it with. ;) If you do, make sure you get the right thread pitch M10 x1.5 is the standard thread , 1.25 is the fine thread.
     
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  10. EddyP

    EddyP Member

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    518
    Location:
    Northants
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  11. tom2207 Member

    Messages:
    2,033
    Location:
    uk northern ireland
    Welt t's are made of chocolate ,, nasty things , and for the bother of the squares , go with flange nuts , lots easier to find and better to have a bag of them laying about , they always come in handy.
     
  12. daedalusminos Member

    Messages:
    951
    Location:
    Norwich
    What thickness steel are you trying to weld it to?

    I have no problems with standard self colour or ground off BZP - 3 spots on alternate flats.
     
  13. Screwdriver

    Screwdriver Member

    Messages:
    6,496
    UK London
    You can always dunk them in vinegar first to take off the zinc. That will help...
     
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  14. Popcorn

    Popcorn Member

    Messages:
    421
    Location:
    'ull
    Make a cage/holder and weld that in, basically a cross with a hole in the middle.
    Then bend it around the nut and bend the excess back to form a flange, then weld the flange part.
     
  15. metalmelt Member

    Messages:
    373
    Location:
    UK
    I grind off the BZP first and never have problems.

    It depends on what you are using them for as in most cases a plain nut will suffice or a plain flange nut will be a good substitute, for deeper threads I use BZP connector nuts which are essentially a large nut designed for connecting threaded bar together and are mainly used for hangers in workshops and factories to support overhead fixtures, for light loadings I use the pronged Tee nut which is the light duty thing holding wooden items such as beds together, you insert them into the hole and belt them in with a hammer until the prongs bite into the wood and put a bolt through, you will need to cut the barbs off though.
     
  16. Other Daniel

    Other Daniel Member

    Messages:
    85
    Location:
    France, Charente
    How many do you have to do ?

    ATB,
    Daniel
     
  17. John_d1974 Member

    Messages:
    31
    Location:
    Fife
    4 in total

    I'm welding the nut on to 5mm mild steel, I can weld the steel no prob it just trying to get a decent weld from the nut to the steel
     
  18. Screwdriver

    Screwdriver Member

    Messages:
    6,496
    UK London
    Strip the zinc off with vinegar.
     
  19. John_d1974 Member

    Messages:
    31
    Location:
    Fife
    Grinded it off
     
  20. Screwdriver

    Screwdriver Member

    Messages:
    6,496
    UK London
    Do you have a picture of the weld you're making?
     
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