Author Topic: Miniature mechanical demagnetizer  (Read 347 times)

Offline mklotz

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Miniature mechanical demagnetizer
« on: May 15, 2022, 08:37:33 PM »
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.

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Regards, Marv


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Offline Kim

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Re: Miniature mechanical demagnetizer
« Reply #1 on: May 15, 2022, 08:43:49 PM »
Now that IS pretty cool! :)
Thanks for sharing it, Marv!

Kim

Offline crueby

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Re: Miniature mechanical demagnetizer
« Reply #2 on: May 15, 2022, 08:59:08 PM »
Slick!


How did the soldering gun demag? I remember using one of those...

Offline gbritnell

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Re: Miniature mechanical demagnetizer
« Reply #3 on: May 16, 2022, 12:19:28 PM »
Have to make several of those for me and my machinist friends
Talent unshared is talent wasted.

Offline mklotz

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Re: Miniature mechanical demagnetizer
« Reply #4 on: May 16, 2022, 03:13:36 PM »
Slick!


How did the soldering gun demag? I remember using one of those...

If you remember, the tip on the gun is in the shape of a distorted loop.

With the gun off, insert the tool in the loop but not touching the loop.  Turn the gun on (you may feel the tool vibrate at 60 Hz when you do), then slowly withdraw the tool to a distance of several feet from the gun before turning it off.

The 60 Hz field around the tip scrambles the magnetic dipoles in the tool, corrupting the alignment that made the tool magnetic.

Folks have replaced the supplied tip with a larger loop of heavy wire in order to accommodate larger tools.  I haven't tried that because I have the bulk tape eraser for bigger items.

The rotation of my tool by the Dremel mechanically creates an alternating field so it's doing essentially the same thing as the soldering gun, except doing it mechanically rather than electrically.
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Offline crueby

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Re: Miniature mechanical demagnetizer
« Reply #5 on: May 16, 2022, 03:24:03 PM »
Great explanation, thanks!