Demagnetizing Digital Calipers?

To All:
    What are your thoughts on putting digital calipers on an electric magnetic surface grinder chuck (that has a demagnetizing feature), to
demagnetize them?
Comments:
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BottleBob
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BottleBob wrote:

Didn't know there was such an animal, never seen one.

I've used purpose made demagnetizers on my digital calipers numerous times with no ill effects.
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Black Dragon

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Black Dragon wrote:

BD:
    We've got two of them, one on each surface grinder. When you turn it off it goes through a demagnetizing cycle (you can see the grinding dust on the top of the chuck alternately stand up and lay down). It goes through about 5-8 cycles.     You can also dial in the amount of holding power you want, instead of blocking up the handle on a manual magnetic chuck.
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BottleBob
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probly will cause no ill effects suggest test and report back to us.
I always used a fractional HP squirrerl cage motor such as washing machine but with the rotor removed, pass the item to be demagged through the centre from one end to the other hold tightly and be careful so that it dont get sucked up tight against the stator laminations works great for small tooling items endmills drills videos of younger sister in law stroking my cock between her tits just kidding but YMMV
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wrote:

That demagnitizing cycle, is nothing more than pumping the coils with AC, rather than the normal DC that runs em. Some have a small motor with a cam to actuate a switch to kick in AC, later ones used a timer and relay.
Ive added an AC switch (demagnitize) to most of my electromagnetic chucks. A simple momentary switch that kicks in the unrectified voltage that runs the chuck.
Gunner
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BottleBob wrote:

Take a 1/8 X 1" X 6" parallel and put it on the chuck. Just run the demag cycle without turning the magnet on. Your calipers will end up like the parallel.
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John R. Carroll
www.machiningsolution.com
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I would definitely take the battery out first. If the calipers are like mine they are pretty well powered up all the time (with the dispay turned off). IIRC the calipers work on inducion coils laid on PCB material on the inside face of the slide - maybe the electromagnet could induce currents in these and cause a failure. I'd do it with someone elses first.......
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Den wrote:

Den, Sam, and Others:
    Here is what I did yesterday (before posting my solicitation for comments): I took some digital calipers that I don't use very often, took the battery out, and laid them on the magnetic chuck. Turned on the chuck, then turned it off which makes it go through the demagnetization cycle. I put the batter back in, and they worked as normal. So I went through the same procedure with my good calipers. There seemed to be no ill effects, and the little slivers of metal that sometimes adhere to the tips and interfere with measurements were eliminated. I don't know if repeated demagnetizations might cause problems, but doing it once didn't seem to hurt them.
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Great - now we can all do it with confidence! :)
I don't imagine that it would have any cumulative damaging effect. I do a bit of fine work, at times the tweezers or screw driver becomes slightly magnetized which can get annoying. I'm pretty sure that even using an AC driven electromagnet, the tools can still be left magnetized if the coil is de-engergised on the peak of the current cycle. If this happens repeating the process until you power down the coil at a low current point should fix it. CRT TV & computer monitors have a coil around the face of the tube for degausing. These have a varistor that slowly reduces the AC current to zero to minimise any residual magnetism, this is the bit that quietly goes "baarp" when you turn the old CRT monitors on.
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I have had good luck just placing them on a medium size transformer.
Regards, Stan-
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BottleBob wrote:

I demagnetize all my stuff with a Weller soldering gun. Tiny stuff, up to tweezers size, I actually pass through the loop of the heating tip. Larger stuff like calipers, I pass by the side of the tip so it takes several seconds to pass the entire item through the field. I energize the gun first, place the item quickly in the field, and then remove slowly before releasing the gun's trigger. If you have the item near the tip when you let go, it will leave the item magnetized.
Jon
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