tube bending experts

  1. johnakay

    johnakay Member

    Messages:
    1,467
    teesside
    manage to make a former for bending 22mm ERW tubing.
    I had a 20mm former and grinded that out etc and a linisher to get the curve.
    its roughly 3".1/4 -3.5" radius on a 5" former.
    it wont have it.
    I think the radius is to small to get an even bend.
    that's probably why Hilmor only do a 8" former or there about.
    what do you experts think?
     
  2. Mikes Member

    Messages:
    301
    Location:
    Hutton, Essex
    What wall thickness? if it's thin, the only way of doing it is with a mandrel bender or by heating the pipe with oxy/acetylene and pulling it around a former manually. It's hard work but you can get some very neat bends this way with practice. Alternatively, is it something that you could use 1/2" BS1387 mild steel pipe (typical commercial heating pipework) which has an o.d. of 21.70 mm . This could be pulled using a hydraulic bender and typically a former for this size has a good tight radius. You could even use this pipe and weld bends to it.
     
    metalmelt likes this.
  3. addjunkie

    addjunkie Member

    Messages:
    6,482
    Location:
    Northumberland. Reet oot in the sticks
    I have a el32 conduit hilmor bender, does 1inch tube no bother at all but from memory its 41/2 inch clr. The standard conduit dies have a deep grove to support the sidewall during the bend. I have other dies too, slightly smaller clr for 20 tube.
     
    metalmelt, Parm and dobbslc like this.
  4. Agroshield Member

    Messages:
    1,389
    When you mention a 20mm former, that makes me think you are using a conduit bender, with just a roller on the top of it.

    Maybe consider converting it to, or buying a former from, the type of bender used for copper plumbing pipe. In that, the roller presses on the outer former, which is kinder to the pipe.

    You could also try filling it with well-packed kiln-dried sand and seeing if that makes any difference.
     
  5. outofthefire

    outofthefire Member

    Messages:
    2,436
    Leeds
    Fill it with kiln dried silver and warm it up if necessary it'll bend without kinking.
     
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  6. johnakay

    johnakay Member

    Messages:
    1,467
    teesside
    this is my current bender see pics.it is based on a hilmor.
    former is specially made to get the correct bend. hilmor isn't quite right.
    20 mm former was grinded out . it should bend the 22mm x 1.5mm wall.
    but I think its on a sharp side.
    I dont want nor am I going to start packing the tubing with sand etc.
    everything is bent by hand.
    I can get 19mm x 1.5mm bent easily enough so maybe 22 is asking to much on such a small radius.
     
    • 251731-a54c6c9978a6594fed8f6b5f86dcd6f2.jpg
    Morrisman likes this.
  7. Agroshield Member

    Messages:
    1,389
    If it is ERW tube, have you experimented with the position of the seam? Inside or outside of the bend might make the difference. From your photo, it looks like a concave roller held by the yellow pin. How closely does it match the OD of the tube? Where does it press on the tube relative to where the inside of the bend touches the inner former? A good clamp on the inside of the block that retains the end of the tube, to stop it moving laterally might help.

    Have a look at this:

    https://pro-tools.com/blogs/protool...to-the-center-of-the-centerline-radius-debate

    (Also, for backup info: http://files.engineering.com/download.aspx?folder=329c633c-d992-46da-9cc2-ed01a5e2e8ee&file=tube.pdf )

    and work out your wall factor and 'D'. See where it lies on the graph and then you will have an idea of the direction in which to proceed.
     
    I/Mx likes this.
  8. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Messages:
    16,050
    Location:
    East Yorkshire
    Post a picture of the failed bend
     
  9. johnakay

    johnakay Member

    Messages:
    1,467
    teesside
    see picture of former for size roughly.
    on the 1st picture of the failed bend you can see where it failed on the inside and slightly squared off on the outside.
    the other was done on the hilmor former good but radius is to big. DSC01365.JPG DSC01367.JPG DSC01368.JPG DSC01369.JPG DSC01370.JPG DSC01371.JPG
     
  10. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Messages:
    16,050
    Location:
    East Yorkshire
    I dont think you can fault that considering its ERW.
     
    metalmelt likes this.
  11. johnakay

    johnakay Member

    Messages:
    1,467
    teesside
    I dont have a problem with a Hilmor former due to its larger size.
    across it measure 147 mm(inside)the home made one is about 90 mm. so theres a big difference .
    bought a 5.5" aluminium round bar last week.
    the biggest I'll be able to machine out will be 110mm.
    do you guys think this will do?
    I know I'm asking a million dollar question.
     
  12. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Messages:
    16,050
    Location:
    East Yorkshire
    You are asking too much of erw. 90mm CLR is very small. Better off using CDS
     
  13. johnakay

    johnakay Member

    Messages:
    1,467
    teesside
    thats why I'm asking on here.

    what is CDS?
     
  14. Richiew Forum Supporter

    Messages:
    1,129
    Location:
    Teesside, England
    Cold drawn seamless (tube)
     
    johnakay likes this.
  15. addjunkie

    addjunkie Member

    Messages:
    6,482
    Location:
    Northumberland. Reet oot in the sticks
    Also called CFS3
     
  16. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Messages:
    16,050
    Location:
    East Yorkshire
    addjunkie likes this.
  17. johnakay

    johnakay Member

    Messages:
    1,467
    teesside
    after much thoughts. I think I know where a I'm going wrong.
    in the picture below that is where I start to bend on the outer roller.
    so its not getting the support at the beginning ,that's probably why its not working.
    it should get the support at start of the bend.
    I'm only doing a 90 degree bend so it should work,I'll have a look tomorrow.
     
    • 126386630_3818629328147564_1017331766587136054_n.jpg
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