Everything is Becoming Magnetized! Help!

[Lloyd-ss]

I am noticing more and more things in my shop getting magnetized: tweezers, cut-off blades, HSS tools, chuck jaws, etc, etc.
Nothing serious, but pretty annoying.

Do I need a demagnetizer? I have a couple of powerful 3" horse shoe magnets if they are of any help. (And no, they are not setting on my tools, LOL.)
Thx, Lloyd

 

[mklotz]

If you don't have a soldering gun or a bulk tape eraser, make one of these...

https://www.homemadetools.net/forum/diy-demagnetising-tool-works-72881#post203385

 

[Lloyd-ss]

If you don't have a soldering gun or a bulk tape eraser, make one of these...

https://www.homemadetools.net/forum/diy-demagnetising-tool-works-72881#post203385

Marv, Thanks!
I watched the video and I've gota piece of Delrin for the shaft part of the tool and a bunch of rare earth magnets to stick in some drilled pockets in the delrin. We shall see how it turns out!
Lloyd

 

[stanstocker]

I've used the coil and frame from fan motors such as those in bathroom fans to build demagnetizers. Hook up a line cord, insulate the connections, and only turn on for 30 seconds to a minute tops. The frame and coil will heat up pretty quickly. Just turn on, pass the item to demag into the opening the rotor used to occupy, withdraw fairly slowly, and turn off.

These will easily demag 1/2 inch end mills, allen keys, screwdrivers, and most anything else that is less than an inch or do in diameter. Anything my watch makers demagnetizer wouldn't handle one of these would. You can buy an entire bathroom fan for under $15 at most big box stores, although it bothers me to throw most of the thing out just to be left with the coil and frame. An old motor being replaced is less wasteful, but they often are so grungy that you won't want to touch the thing!

 

[timo_gross]

I paid roughly 100 US for a 110V small demagnitizer, similar to this one. Maybe it is helpful for a "make or buy" decision. It can also be used for bigger parts.

 

[BaronJ]

Hi Lloyd, Guys,

I do the same as Stan and use a motor with the rotor removed, if you have access to a single or three phase motor, say half to 1 Hp removing the rotor and passing larger work through the core a couple of times works well to de-mag chuck jaws and collets, larger things. Use a piece of wood to push things through. As Stan notes without the rotor the windings get hot very quickly. With a three phase motor you only need to energize one winding, but beware that voltage will be induced in the other windings and could shock you if you touched the terminals.

 

[Lloyd-ss]

Marv,
I like quick and dirty projects that cost nothing and that can distract me from what really needs to be done, LOL.

Here are some pics of my version of the demagnetizer like you made. It's 1" dia Delrin, with a 1/2" shank and a 3/8" hole part way thru the middle. Pairs of the 5mm x 5mm rare earth magnets are press fit into the randomly drilled .193 dia holes. Polarities kind of alternate hole to hole, but there are a couple of adjacent holes where the polarities are the same. I did some reading too and it mentions a random magnetic field to accomplish the demagnetizing. I am just playing with it now and demagnetized a burr knife and some tweezers. It took some playing around to figure out what works, and I still need to play some more.
I was having a problem with the tweezers picking up a .093 check ball when I didn't want them to. I tried the tweezers across the rotating face and then also withdrawing them from the rotating center hole of the demagnetizer. That worked a little. Then it dawned on me that the check ball was probably magnetized too. So I held the check ball in the tweezers and demagnetized them both together. And it worked! Not a hint of them sticking together.
I don't know if it will do anything very big, but I will find out.

Thanks for that tip, Marv.

Lloyd

 

[BaronJ]

Hi Guys,

Sorry I forgot to add pictures of my small de mag coil ! The hole is about 25 mm diameter.

 

[mklotz]

Marv,
I like quick and dirty projects that cost nothing and that can distract me from what really needs to be done, LOL.

Here are some pics of my version of the demagnetizer like you made. It's 1" dia Delrin, with a 1/2" shank and a 3/8" hole part way thru the middle. Pairs of the 5mm x 5mm rare earth magnets are press fit into the randomly drilled .193 dia holes. Polarities kind of alternate hole to hole, but there are a couple of adjacent holes where the polarities are the same. I did some reading too and it mentions a random magnetic field to accomplish the demagnetizing. I am just playing with it now and demagnetized a burr knife and some tweezers. It took some playing around to figure out what works, and I still need to play some more.
I was having a problem with the tweezers picking up a .093 check ball when I didn't want them to. I tried the tweezers across the rotating face and then also withdrawing them from the rotating center hole of the demagnetizer. That worked a little. Then it dawned on me that the check ball was probably magnetized too. So I held the check ball in the tweezers and demagnetized them both together. And it worked! Not a hint of them sticking together.
I don't know if it will do anything very big, but I will find out.

Thanks for that tip, Marv.

Lloyd

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The on axis hole between the magnets in your device is ok but really isn't needed. The technique I use is to hold the tweezers (or whatever) perpendicular to the spinning tool and a short distance in front of it; you'll need to resist the attraction of the magnets, the tweezers shouldn't touch the magnets. From this position and with the tool still spinning, slowly withdraw the tweezers to a distance of a foot or so from the tool. Give this procedure a try on your next demagnetization attempt.

My version has the magnets epoxied to a steel fender washer (no central hole like yours) and works very well used in the manner outlined above.