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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

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Old 7th Dec 2017, 10:43 pm   #1
Bazz4CQJ
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Default De-magnetising Tools

I'm not sure why, but suddenly it seems that all my small screwdrivers, pliers etc etc have become irritatingly magnetic. I'm thinking of wrapping several turns of thick enamelled wire around a hefty nail, and just very briefly connecting that on to an old transformer from a car battery charger while the nail touches the tools.

Anyone been down this path previously?

B
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Old 7th Dec 2017, 11:31 pm   #2
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Default Re: De-magnetising Tools

I believe you need to stick them in the bore of a reasonable sized solenoid, then feed the coil with an AC supply you can wind up and down slowly. A Variac feeding a suitably rated transformer will do. Wind it up, then wind it back to zero slowly.
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Old 8th Dec 2017, 12:24 am   #3
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Arrow Re: De-magnetising Tools

Here, I have a couple of 'magnetizers / de-magnetizers'. They're about 2" square by 1" thick with an irregular-shaped hole that goes right through. They are red in colour. In one part of that hole, you insert the tool you want magnetized; in the other part, the reverse - for de-magnetization. I believe they came from Farnell or RS many years ago: may still be available; very useful gadget.

As for screwdrivers that seem to have strangely become magnetized, yes, I've had that - and, occasionally, still do. Why it happens, I don't know - and I've never attempted to find out why. I suspect that one screwdriver (or any other tool) gets in the zone of a magnetic field somehow and then with typical juggling around of tools on the bench, its proximity to other ferrous tools makes them magnetic, too. I suppose that the sudden collapse of a substantial a.c. current could have same magnetizing effect. In the old days of 3" FDDs, that 'magnetic screwdriver' syndrome was a real hazard to us PC technicians! When in the field, I always carried more that one diagnostic floppy disk!

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Old 8th Dec 2017, 12:31 am   #4
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Default Re: De-magnetising Tools

I use a magnetic wall rack for tools. they all get magnetised, but I find it quite handy. Screws don't fall on the floor. and the bits of component lead snipped off stay on the cutters (why are all leads ferrous these days?) I never work on tape decks!
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Old 8th Dec 2017, 5:12 am   #5
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Default Re: De-magnetising Tools

I find magnetised tools to be a pain. They never really hold what you want them to hold, but they are good at pulling other parts out of place (try fitting a screw with a magnetised screwdriver through a set of washers/spacers and see the latter go all over the place). Although off-topic, try assembling the diaphragm blades of a camera lens (would making it a camcorder lens put it on-topic? ) with magnetised tweezers!

I bought a few non-magnetic tools (a couple of screwdrivers and a pair of tweezers). I am trying desperately to think of a good excuse (other than the price of over 200) not to buy a set of non-magnetic watchmaker's screwdrivers.

I have had some success demagnetising small tools using the bulk tape eraser (put the tool on top, turn it on, remove the tool to arms length).
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Old 8th Dec 2017, 5:53 am   #6
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Default Re: De-magnetising Tools

Would a tape head demagnetiser do the job? I had one once, somewhere.
My stainless 'Cheap' tweezer set is non magnetic.
Keep those neodymium magnets away from everything.
Fascinates me how a hard drive can be corrupted by a magnetic field yet there is a powerful neodymium magnet inside.
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Old 8th Dec 2017, 6:31 am   #7
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Default Re: De-magnetising Tools

"I find magnetised tools to be a pain" ditto. I've tried the head de-gausser on a few of my magnetised screwdrivers with mixed success; it doesn't work well if at all.

To hold screws on the ends of screw drivers I use blue tack or a little gadget that slips onto the shaft and holds the screwhead with two jars.

What is the low down with de magnetising? Are we trying to to get all the electrons in a haphazard config as opposed to lined up?

Andy.
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Old 8th Dec 2017, 7:13 am   #8
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Default Re: De-magnetising Tools

I bought one of these a few years ago, Ive never really used it so not sure how effective it is.

https://www.rapidonline.com/toolcraf...etiser-51-2561

John
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Old 8th Dec 2017, 10:14 am   #9
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Arrow Re: De-magnetising Tools

That's it! The de-mag. tool I referred to in post #3. (Although this one is blue).

Al.
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Old 8th Dec 2017, 10:37 am   #10
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Default Re: De-magnetising Tools

Quote:
Originally Posted by Herald1360 View Post
I believe you need to stick them in the bore of a reasonable sized solenoid, then feed the coil with an AC supply you can wind up and down slowly. A Variac feeding a suitably rated transformer will do. Wind it up, then wind it back to zero slowly.
That'll work! But another way is to leave the solenoid energised and just slowly withdraw the tool to arms length.

If you can feel the tool vibrating in your hand whilst in the solenoid, the field is probably strong enough.
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Old 8th Dec 2017, 7:42 pm   #11
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Default Re: De-magnetising Tools

Thanks for the replies. Al's demag tool is shown alternatively magnetising and then demagetising screwdrivers on Youtube https://www.youtube.com/watch?v=dSHSoIqfZ04, and is available online at prices from about 3 (inc P&P) upwards. I searched Google before starting the thread and didn't seem to find much, but searching Youtube gets a variety of hits including home-made solenoids.

Given that there are times when a magnetised screwdriver could be either desirable or annoying, that particular tool seems quiet useful.

B

edit see also https://www.youtube.com/watch?v=81Vuhe-ytz4
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Old 8th Dec 2017, 8:02 pm   #12
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Default Re: De-magnetising Tools

Oddly in a restaurant tonight I had a magnetised knife, I don't know how it came to be on that state.
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Old 8th Dec 2017, 8:11 pm   #13
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Default Re: De-magnetising Tools

Here's my demagger, it works well
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Old 8th Dec 2017, 9:50 pm   #14
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Default Re: De-magnetising Tools

The old ones are the best.

If you have a Weller type soldering gun just hold it near whatever you want to demagnetise, pull the trigger then move the gun in decreasing circles away from the item being demagnetised. When the gun is a few feet away from the item let go of the trigger. You should find the item is now demagnetised.
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Old 8th Dec 2017, 10:41 pm   #15
60 oldjohn
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Default Re: De-magnetising Tools

I will have to try this method. I very nearly asked the same question how to demagnetise tools, after seeing the plastic blue and red magnetisers / demagnetisers for sale. I looked on You Tube someone used a ring speaker magnet it did not work for me. Someone else made simple coil a single layer of heavy duty wire and connected it in place of the soldering tip of a Weller soldering gun, it demagnetised a swathed up drill bit instantly.


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Old 9th Dec 2017, 11:26 am   #16
Phil G4SPZ
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Default Re: De-magnetising Tools

Quote:
Originally Posted by Diabolical Artificer View Post
What is the low down with de magnetising? Are we trying to to get all the electrons in a haphazard config as opposed to lined up?
From memory, the process involves taking the metal through an ever-decreasing series of M-H hysteresis loops.

https://en.m.wikipedia.org/wiki/Magnetic_hysteresis
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Old 9th Dec 2017, 5:37 pm   #17
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Default Re: De-magnetising Tools

CPC Farnell do a demagnetiser/magnetiser in one tool for 1.34.
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Old 9th Dec 2017, 5:48 pm   #18
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Default Re: De-magnetising Tools

Quote:
Originally Posted by Diabolical Artificer View Post
"I find magnetised tools to be a pain" ditto. I've tried the head de-gausser on a few of my magnetised screwdrivers with mixed success; it doesn't work well if at all.

To hold screws on the ends of screw drivers I use blue tack or a little gadget that slips onto the shaft and holds the screwhead with two jars.

What is the low down with de magnetising? Are we trying to to get all the electrons in a haphazard config as opposed to lined up?

Andy.
Same as a delousing (degaussing) coil, a fiver for every time I've done that:

https://www.youtube.com/watch?v=3pVLizAHby4

Lawrence.
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