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  1. #1
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
    Age
    72
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    3,102

    Default Magnet physics question

    I am considering building a small permanent magnetic chuck for my rotary table.
    The constuction is simple: a slotted aluminium or brass front disc, a steel back disc with mounting provisions and a spacer/sealing strip around the outside. The latter may be made from a short ring of pipe, counterbored to fit the front and back discs, to fix them and to space them apart.
    The front disc would have slots milled through to position and locate soft iron pole strips - flush with the front and protruding to cover the entire side of one of the magnets. Thus passing the magnetic field to the face of the front disc. I would epoxy all the pieces to each other and to the front disc. Maybe all of it.

    The general arangement of magnets and pole pieces could be something like this:
    Magnet chuck 1.jpg

    The first question is: would that work at all? I imagine that a workpiece on the front of the chuck would complete circuits of magnetic force lines and thus get 'stuck'.
    The second question is, if I arrange additional magnets facing opposite directions (N/S), would they support or hinder/repel the magnetic lines. I realise that they will be facing N-N and S-S, but with the pole pieces in between.

    Like this:
    Magnet chuck 2.jpg

    The last question is, since there is no mechanism to turn the magnets off, do I have to have 'keepers' to preserve the magnets and/or to stop them picking up iron dust from everywhere while not in use?

    All comments and information is appreciated.
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  2. #2
    BobL is offline Member: Blue and white apron brigade
    Join Date
    Feb 2006
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    Perth
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    7,182

    Default

    I would make sure all the N/S pair up as much as possible.

    What about staging a mock up and use some luggage scales to see how much each holds?

  3. #3
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
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    72
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    Default

    Yes, Bob, that was going to be one of my moves - if a good explanation couldn't be found. I kind of can't visualise what the magnetic lines would be doing with the interspaced magnets in the second image.
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  4. #4
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

    Default

    Have you considered building an electromagnet powered by a computer power supply?
    Gold, the colour of choice for the discerning person.

  5. #5
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
    Age
    72
    Posts
    3,102

    Default

    I have R.C., but I'm fascinated by these permanent magnets and the lack of need for slip rings and cables..... Maybe MK II
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

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