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Magnet as workbench swarf-sweeper, and compass

Discussion in 'General Electronics Discussion' started by FuZZ1L0G1C, Jun 10, 2019.

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  1. FuZZ1L0G1C


    Mar 25, 2014
    Magnet tricks.gif Cleaning swarf (iron dust) off a magnet:
    While cleaning up ferrous metal filings recently, using a super-magnet from an old microwave's magnetron, I realized that trying to get the metal dust (swarf) off the powerful bare magnet was easier said than done!
    Eventually, through pulling clumps off under a running tap, (wearing nitrile rubber gloves), most of the swarf was removed.
    However, there were still bits stuck to the magnet, ready to penentrate skin that contacted it.
    My eventual solution was to paint the entire magnet with quick-drying paint (road-marker used, but any PVA-type paint or flexible glue should work).
    Once dry, the coating is simply peeled off, taking the offending filings with it.

    Preventing magnet contamination:
    On my next bench-sweeps, I used a plastic shopping carrier, then a plastic cold-drink bottle cut in half.
    The plastic carrier worked best, as when removed, the bag can first be closed around filings, before pulling away from magnet.
    The bottle method tends to "drag" the filings up the outer sides as the magnet is drawn out of the container.

    Possible use for ferrous powder collected:
    Not wanting to waste this collection of filings (more of a powdered ferrous "dust" from grinding), I am collecting this into a lidded tupperware container.
    I recently mixed a thick paste of this "ferrite powder" with fibreglass resin epoxy, which sets in about 30 minutes, working the mix into a 20mm pvc conduit coupling, as a home-made ferrous "powdered core", for a home-wound inductor.
    This increased the inductance, while not creating as much "kickback" as a solid (thick bolt) core test.
    Plan to also try oxidizing the ferrous powder, through table salt solution, acid, or ferric chloride.

    As a Compass (or magnet's pole finder):
    Remembering the "bar-magnet-on-a-cork" compass experiment in school physics, I suspended the ring magnet on a 1m length of cotton, then already knowing where North is, found that one flat face of the ring always swings to the Earth's magnetic North.
    So this is a magnet with poles through the "hole" of the toroid.
    As N attracts S, the side facing North must be the South of the magnet.
    Last edited: Jun 10, 2019
  2. Bluejets


    Oct 5, 2014
    Wrap the magnet in a rag, works for me for many years ( and I'm an old bloke).
    FuZZ1L0G1C likes this.
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