EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: m3vuv on December 21, 2019, 07:31:27 pm
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Hi all,a lot of my small screwdrivers etc have become magnatized,does anyone know of a simple wat to de magnetise them?,cheers m3vuv 73.
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put in a proximity of a low frequency AC electromagnet and slowly move away.
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Or get this thing:
https://www.banggood.com/Wowstick-Magnetizer-Demagnetizer-For-Mijia-Kits-1FS1F1P-Electric-Screwdrivers-p-1333573.html?cur_warehouse=CN (https://www.banggood.com/Wowstick-Magnetizer-Demagnetizer-For-Mijia-Kits-1FS1F1P-Electric-Screwdrivers-p-1333573.html?cur_warehouse=CN)
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I have two very old tape erasers and perhaps a tape head demagnetizer that do the job well. I doubt those are still available but check at swap meets.
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Here are more choices for a magnetizer/demagnetizer tool:
https://www.amazon.com/s?k=demagnetizer%2Fmagnetizer&crid=I7W155MQ20MT&sprefix=demag%2Caps%2C249&ref=nb_sb_ss_i_4_5 (https://www.amazon.com/s?k=demagnetizer%2Fmagnetizer&crid=I7W155MQ20MT&sprefix=demag%2Caps%2C249&ref=nb_sb_ss_i_4_5)
I consider it to be one of the essential tools to have, especially if you are working with very small screws in tight places.
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CRT degaussing wands and coils used to be readily available. You can use any kind of electromagnet powered by AC though. The coil salvaged from an old shaded pole motor would probably work well for degaussing screwdrivers.
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would holding them next to a rewound(secondary) mot work?
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Just the outside of a motor will not produce much field. So this would not work. It would usually need a modification (e.g. remove the rotor) this may well require to run at a reduced voltage too. A possible source for a suitable AC magnet could be an AC relay, or some linear magnetic actuators. Motors tend to be relatively large. There are possibly several options in the junk bin.
There are also some permanent magnet solutions to get a reasonable demagnetization. There are some that combine magnetize and demagnetize. It is not as good as an AC field be it could be good enough.
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"MOT" was likely a Microwave Oven Transformer.
OP: No, it won't work that way. You need the magnetic flux to go through your screwdriver. The core of the transformer would need to be cut (the I section of the core ground off off the MOT, but then you could only run it with lowered voltage input).
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Do you happen to have a Weller soldering gun? Put the tools near the body of the gun (not the tip), pull the trigger, and gradually pull the tools away while the gun is still on, then release the trigger.
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Give them a short sharp shock,bang the screwdriver against the work bench or lump of metal a few times.
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You can use a magnet. Rub against either pole to magnetize, rub against the side where you have both poles to demagnetize.
Here is a picture of a magnetizer/demagnetizer to easily demonstrate.
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Just out of curiosity, why do you want to demagnetize? I buy magnetized kits and if I have stuff not magnetized already like my Xcelite 99 series, I magnetize them. I even keep a magnetizer/demagnetizer in my tool bag in case anything gets weak. Never have had an issue in 20 years of field service repairs.
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Best thing in the world is one of the old Weller transformer-type soldering guns, the ones with the two-pronged copper tip that is bolted into two
threaded posts that stick out the front of the gun. You squeeze the trigger and then pass the tool through the loop of the tip, pull back out
and then hold far away from the gun when you release the trigger. This totally demagnetizes the tool.
Jon
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Just out of curiosity, why do you want to demagnetize? I buy magnetized kits and if I have stuff not magnetized already like my Xcelite 99 series, I magnetize them. I even keep a magnetizer/demagnetizer in my tool bag in case anything gets weak. Never have had an issue in 20 years of field service repairs.
It depends on the job. For some tasks a magnetic tool is good and for others it is causing problems. With a magnetic screw driver the screw on the heat tends to hit the side of a magnetic material. It is especially trouble with a magnetic washer. Magnetized tweezers can be troublesome with small parts - here stainless steel is a common solution, as the magnetic version does not make much sense.
The cases are rare but sometimes one wants it non magnetic.
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Yes magneetized tools can be a nuisance, in particular with small parts.
Additionally, magnetic tools can magnetize delicate mechanism parts and affect operation. A clock or watch movement is an example.
I demagnitize my tools occasionally. Scredrivers in particular. I have some tweezers that cannot be magnetized and use those occasionally. They are braxx or fiber.