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Miniature mechanical demagnetizer

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  • J Tiers
    replied
    That is because the field from the head is primarily "across" between the two parts of the record (or erase) head. It does not penetrate outward very far at all. it's really not so much strength as design of the recording field.

    Your case of flipped tape should have had a lack of highs, as well as weak recording with the low end of the previous recording still present.

    But as far as demagging anything besides tape, ain't gonna happen, just because in that case it IS too weak.

    Leave a comment:


  • BCRider
    replied
    Originally posted by boslab View Post
    Thanks for posting, I’d never considered spinning as a demagnetise option, I wondered once if the erase head off an old reel to reel might work, it never got past a thought, far simpler to construct.
    mark
    Forgot about that post..... Boslab, fuggid'boud'id. Those heads are very weak in terms of any sort of bulk product effect. They are only strong enough to erase a single layer of tape that has the oxide of the tape running right across the face.

    I used to run a lot of reel to reel stuff. By some very odd happenstance I flipped a reel and fast wound it inside out onto another reel. Then I tried to record over it and it didn't work since the oxide layer was on the wrong side. The erase head did not get all the old sound off and the record head only got SOME of the audio through the film to the oxide. It was a very odd doubled sort of song over song schmozzle. That's how weak an erase head on a recorder is..... It was a bit of a head scratcher until I noticed the shiny side was on the wrong side.....

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  • PStechPaul
    replied
    Another simple mechanical tool:
    https://www.hsmagnets.com/blog/tool-...gnetizer-work/

    Click image for larger version

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    Leave a comment:


  • darryl
    replied
    That's interesting- I wonder if I can fit that into my cassette player to demag the heads-

    One day I had a ferrite magnet from a speaker in one hand, and a neodymium magnet in the other. I found I could 'print' magnetism into and out of the ferrite ring with the more powerful magnet- in this case the desirable effect would be to increase the strength in the speaker magnet if it had become weak. By adding a steel flux path to the stronger magnet I probably could have brought the ferrite magnet back to something close to its maximum capability. Or to reduce its magnetism to zero, or even magnetize it in the opposite direction.

    In any case, you will have to take great care to demagnetize something with these strong magnets, rather than leave an unknown state of magnetism behind.

    Leave a comment:


  • BCRider
    replied
    Originally posted by mklotz View Post

    I intend to wrap it in a discarded tinfoil candy wrapper before dropping it into the toolbox. I do the same with the magnetic pickup tools. Peel off wrapper and swarf, discard, eat a piece of candy to celebrate your cleverness, and rewrap.
    I....Am..... SOOOO.....Stealing.... Your...... Idea....... BEST EVAR! ! !



    <BCR bows in deep respect for the WonderMan>

    Leave a comment:


  • mklotz
    replied
    Originally posted by BCRider View Post
    Brilliant. I'm going to make up a similar simple bolt and fender washer setup for use in my hand drill. And of course if it fits in the hand drill it'll fit in the drill press too.

    As a fancy addition I like the idea of a plastic or aluminium sheet disc with holes for the magnets. That way I can bed them in with some epoxy for a smooth outer finish to the overall magnetic disc. Not so much to hold them but to make it easier to wipe away the inevitable swarf that collects on the magnets. If left "naked to the world" like the setup in your picture I think you're going to find that a lot of swarf builds up in the nooks and crannies around the magnets and is near impossible to clean away.
    I intend to wrap it in a discarded tinfoil candy wrapper before dropping it into the toolbox. I do the same with the magnetic pickup tools. Peel off wrapper and swarf, discard, eat a piece of candy to celebrate your cleverness, and rewrap.

    Leave a comment:


  • BCRider
    replied
    Brilliant. I'm going to make up a similar simple bolt and fender washer setup for use in my hand drill. And of course if it fits in the hand drill it'll fit in the drill press too.

    As a fancy addition I like the idea of a plastic or aluminium sheet disc with holes for the magnets. That way I can bed them in with some epoxy for a smooth outer finish to the overall magnetic disc. Not so much to hold them but to make it easier to wipe away the inevitable swarf that collects on the magnets. If left "naked to the world" like the setup in your picture I think you're going to find that a lot of swarf builds up in the nooks and crannies around the magnets and is near impossible to clean away.

    Leave a comment:


  • boslab
    replied
    Thanks for posting, I’d never considered spinning as a demagnetise option, I wondered once if the erase head off an old reel to reel might work, it never got past a thought, far simpler to construct.
    mark

    Leave a comment:


  • Jerrythepilot
    replied
    Thanks for sharing this, looks great!

    Leave a comment:


  • Robg
    replied
    Quick, simple & effective. I like it!!

    Leave a comment:


  • mklotz
    started a topic Miniature mechanical demagnetizer

    Miniature mechanical demagnetizer

    For bigger tools, I demagnetize with a bulk tape eraser (remember those?). For smaller tools I use my old Weller soldering gun.

    However, when I saw Mark Presling's ingenious mechanical demagnetizer...

    https://www.homemadetools.net/forum/...ol-works-72881

    I had to have a miniature version for my in-house small job bench. Beyond its undeniable coolness, it would save me the trip to the garage to retrIeve the soldering gun and could be spun with any of the Dremel/Foredom-like tools lying on the bench.

    I was fortunate to have some 1" fender washers with a 1/8" hole that just fits a 5-40 screw to provide a shaft to grasp in the Dremel. Six Harbor Freight 5/16" diameter super magnets were epoxied to the washer in an alternating polarity configuration.

    Spun at even a low speed, it does a fine job of demagnetizing small tools.

    Click image for larger version

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