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Electro magnet

Discussion in 'General Electronics Discussion' started by gregrae, Sep 14, 2015.

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  1. gregrae

    gregrae

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    Jan 12, 2011
    I would like to make a electro magnet for my sheet metal bender .
    The bender will be 1 metre long .
    The sheet metal will be 1.8 mm thick
    How do I go about this project . I require a strong magnetic field.
     
    Last edited by a moderator: Sep 15, 2015
  2. Old Steve

    Old Steve

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    Jul 23, 2015
    What about using ready-made, large solenoids at each end of the clamp bar?
    It would take a lot of trial-and-error to design and make your own electro-magnets.
    I had to look at this video first, to see exactly what's required:-


    Something like this:-

    RUSHMORE.jpg
     
    Last edited: Sep 14, 2015
  3. gregrae

    gregrae

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    Jan 12, 2011
    The marina bender is the style I would like to make but do not know what is required to make the electro magnet
     
  4. Old Steve

    Old Steve

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    Jul 23, 2015
    I have no idea what a marina bender is.

    Would it need a pair of piston-style electromagnets, like in the picture I posted?

    Perhaps some more info would help. A drawing or picture maybe.
     
  5. gregrae

    gregrae

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    Jan 12, 2011
    I would like to apologise for not checking what I had typed. It is a , Magna bender.
    What I would like to know is how I go about making several Electro Magnets 5 or 6 which I will place in non magnetic case with a iron top. Can you advise me
     
  6. gregrae

    gregrae

    67
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    Jan 12, 2011
    I have found this 12 v electro magnet with a 2.5 kg force. ( is this enough force ) as I cannot under stand this force. Something of this weight , would that equal the force
    Do you think that 8 of these would do the job .
    What size power supply would I require
     

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  7. Old Steve

    Old Steve

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    Jul 23, 2015
    Way too weak. With 8, you'd only have 20kg of force to clamp the bar.
    And it would be near impossible to connect a group of 4 to each end.

    Better is to connect a single, long-travel, piston type solenoid to each end of the clamping bar from underneath, which is the way the 'Magna Bender' probably does it.

    I can't really help with the amount of force needed, except to say you need to imagine what amount of weight, when placed on the clamping bar, would hold the sheet in place. It would be quite a lot, more like the solenoid I posted a picture of last night.
     
  8. gregrae

    gregrae

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    Jan 12, 2011
    I watched the video on the bender and half way through the video there is s section where the bending segments are clamped by a magnet this is what I am trying to build , this creates versatility of the bender and allowes multiple bends.
     
  9. Old Steve

    Old Steve

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    Jul 23, 2015
    Right, now I'm 100% with you. I have to confess that I only watched the first minute or two yesterday, since the video is 10 minutes long..
    It'a a nice machine, isn't it?

    So, it doesn't use solenoids at all. It's a full-length, very powerful, electromagnet. I didn't realise it was open-ended, either.

    In the middle of the video, those aren't magnets. Just small blocks of ferrous metal that the main electromagnet attracts.

    It would be nice to see inside it.

    It's probably one or maybe a couple of electromagnets, attached to the inside of the clamping table, similar to my drawing below:-
    (You could use a row of them if needed.)

    Magna Bend.JPG

    I can't actually help with designing the electromagnets, (never tried it), but maybe someone else can.

    Or you could experiment, with very thick winding wire, an iron core and heaps of windings. Not sure about power supply size though. Big.

    Edit: Just thinking about it, the top of the clamping table would need to be carefully chosen for low remanence, so that it didn't remain magnetic after the power was switched off. Maybe even a special iron alloy. I'm not sure about that bit.
     
    Last edited: Sep 15, 2015
  10. gregrae

    gregrae

    67
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    Jan 12, 2011
  11. Old Steve

    Old Steve

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    Jul 23, 2015
    It's fairly straightforward, if you carefully read the information on this page, under "TheCoil":-
    http://aaybee.com.au/Magnabend/Building Your Own Magnabend.html
    They explain it all very clearly and I couldn't do better than they have already done.

    Basically, you first need to make a soft-iron core of the correct shape and in a size to suit your intended machine, then use the formulae provided to work out the thickness and length of the wire.

    Mind you, this is the easy bit, compared to the main circuitry described on this page:-
    http://aaybee.com.au/Magnabend/Magnabend Circuit Operation.html

    This is not a project for a novice to attempt. It is extremely dangerous, and one mistake could lead to your death.
    I would advise you to get a suitably qualified person to do all of the electrics, including winding the coil.

    They will understand what's needed and be capable of doing it in a safe manner. You cannot simply build the coil and connect it to power. There is far more to it.

    I'm sorry, but I cannot provide further advice on this project, because then you might try to do it yourself. Already, I've said too much.
     
    davenn and Harald Kapp like this.
  12. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    If you don't understand this information, you're not up to building such a mains powered device. You'll have to take into account safety such as right insulation, protection from overcurrents and overvoltages etc.
    I second Steve's advice: get expert help, don't risk anything!

    For now I'll close this thread to further postings.
     
    hevans1944, davenn and Old Steve like this.
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