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Magnetic indicator base demagnetizing

 

I picked up an old Mitutoyo magnetic indicator stand on ebay for a great price.? Has a bit of very light corrosion that I think I can address pretty easily and even if I can't, it's still very functional as is.

?

The one big issue was it wouldn't turn off completely.? I have it partially apart. I think that issue was the limit screw needed adjustment.? Aligning the magnet manually makes it work perfectly fine.? So far so good.

The last issue is the inside is full of heavy, sticky old grease.? i have the knob removed and the insides are gunked up - I think someone squirted a bunch through the hole on top where the rod attaches, probably decades ago.? I'm at the point where I was going to pull the magnet out so I can clean it off, clean the bore and lightly lube it before putting it back together.

?

But when digging around trying to figure out how to get it apart, I found a lot of threads on machinist forums suggesting that pulling the magnet out would demagnetize it.? Right now, it works pretty well when it's "on" other than the issues above, so I don't want to kill it.

?

I"ve had newer indicator stands apart and pulled the magnets out with no issue, but magnets have come a long way.? This is one of those older indicators where the knob is held in with a pressed ring, rather than the square plate with two screws under the label.? I'm guessing early 70s but maybe older.?


The threads I read never really said if they just pulled the magnet out for a few minutes and then it was dead, or they left it out for a few days sitting on a metal table or something.

?

You guys ever heard of or experienced this?? I could clean it all out with solvent with the magnet still in there, but then I risk getting solvent all over the paint (it does soften slightly when wiped with acetone) and I probably won't get all the old grease out that way.
 

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I think mrpete222 has a tube on taking them apart

animal

On 4/13/24 4:00 PM, chrisser via groups.io wrote:

I picked up an old Mitutoyo magnetic indicator stand on ebay for a great price.? Has a bit of very light corrosion that I think I can address pretty easily and even if I can't, it's still very functional as is.

?

The one big issue was it wouldn't turn off completely.? I have it partially apart. I think that issue was the limit screw needed adjustment.? Aligning the magnet manually makes it work perfectly fine.? So far so good.

The last issue is the inside is full of heavy, sticky old grease.? i have the knob removed and the insides are gunked up - I think someone squirted a bunch through the hole on top where the rod attaches, probably decades ago.? I'm at the point where I was going to pull the magnet out so I can clean it off, clean the bore and lightly lube it before putting it back together.

?

But when digging around trying to figure out how to get it apart, I found a lot of threads on machinist forums suggesting that pulling the magnet out would demagnetize it.? Right now, it works pretty well when it's "on" other than the issues above, so I don't want to kill it.

?

I"ve had newer indicator stands apart and pulled the magnets out with no issue, but magnets have come a long way.? This is one of those older indicators where the knob is held in with a pressed ring, rather than the square plate with two screws under the label.? I'm guessing early 70s but maybe older.?


The threads I read never really said if they just pulled the magnet out for a few minutes and then it was dead, or they left it out for a few days sitting on a metal table or something.

?

You guys ever heard of or experienced this?? I could clean it all out with solvent with the magnet still in there, but then I risk getting solvent all over the paint (it does soften slightly when wiped with acetone) and I probably won't get all the old grease out that way.
 

I doubt that pulling the magnet would de-magnetize it; the base was probably built by inserting a magnet into the housing. Still, to be safe, you could try softening & flushing out the old grease with a wash bottle filled with a petroleum based solvent, NOT acetone. My preference for things like this is whatever version of mineral spirits is cheapest!?

?<??>

(That's a short version of a horribly long link; you can avoid it by searching for, "wash bottle" & picking the cheapest - it should cost under $2, no need for an over priced one.)

You'll probably also want some non-magnetic tools to help dig the old grease out.

Roy
 

FYI If pull apart the magnetic may not work.
I just buy new so know what happened to magnetic. I have magnetic basics some over 60 years old the slowly lost there power over years like a magneto.?
There power last about 25 years.?

Good luck
Dave?
 

I found this youtube video.? At about 13:00 he describes a scratch test to tell if the slug is a real magnet or just a magnetized piece of steel - supposedly the latter can't be removed.

I scratched mine and i'm pretty sure it was a magnet, but I decided to play it safe and cleaned it in place.? Took a big handful of q-tips (don't tell my wife) to get all the gunk out.? Adjusted the stop and it now works great.? Some fine steel wool and simichrome on the rods and they look pretty good.? Cleaned up the light rust on the hardware and touched up with some cold blue and oil.

This is a pic from the ebay ad

image.png

Here's what it looks like now

image.png

Only downside is I had to get the aluminum label off to get at the adjusting screw and it's pretty bent up.? Even with heat, I couldn't get the adhesive to let go and had to slide a utility knife under it to get it loose.

Surprisingly, it's as strong as my Grizzly chinese stand, which is about a dozen years old.? Doesn't come close to the new ones, but I think it will do the job.
On Saturday, April 13th, 2024 at 8:41 PM, Roy via groups.io <roylowenthal@...> wrote:

I doubt that pulling the magnet would de-magnetize it; the base was probably built by inserting a magnet into the housing. Still, to be safe, you could try softening & flushing out the old grease with a wash bottle filled with a petroleum based solvent, NOT acetone. My preference for things like this is whatever version of mineral spirits is cheapest!?

?<??>

(That's a short version of a horribly long link; you can avoid it by searching for, "wash bottle" & picking the cheapest - it should cost under $2, no need for an over priced one.)

You'll probably also want some non-magnetic tools to help dig the old grease out.

Roy

 

The video referenced above

https://www.youtube.com/watch?v=RUV55lXNBaY
 

It depends on the magnetic.?
Like a magnetic chuch there most have a charge magnetic.? If take the chuck apart the magnet will loose most of charge.?

Do not buy use magnetic chuck unless check first.?
I only new one guy who did changing in 1970's.? He build his own charging station using a lot of big capacitors.?

Dave?

Roy
Apr 13? ?
I doubt that pulling the magnet would de-magnetize it; the base was probably built by inserting a magnet into the housing
 

Why would taking it apart lose most of the charge?


On Sun, Apr 14, 2024 at 2:03?PM davesmith1800 via <davesmith1=sbcglobal.net@groups.io> wrote:
It depends on the magnetic.?
Like a magnetic chuch there most have a charge magnetic.? If take the chuck apart the magnet will loose most of charge.?

Do not buy use magnetic chuck unless check first.?
I only new one guy who did changing in 1970's.? He build his own charging station using a lot of big capacitors.?

Dave?
Roy
Apr 13? ?
I doubt that pulling the magnet would de-magnetize it; the base was probably built by inserting a magnet into the housing
 

I do not know.
I told about when asking questions about rebuilding a magneto back in 1972.

Dave?
 


THESE? MAGNETIC? SYSTEM? ARE? DIFFICULT? TO REPRODUCE

the mag? have? to? be? in? the? exact position for? his polarity? ?orientation

if? you? mark? both? mag? for? the? orientation?

no problemo?

you? can? made a system? like this? by? position? the mag? in a? special? position? only?

when? you? turn? one? ?the mage? incrise? ? in? the? other possition? the mag? in NUL

jack 47 71
 


ho? remember? also

only? use? brass tools? to? work on? these??

like? worl? on magnetron??
if? you? work? on magnetron? whit a? iron? toll? you modify? his mag power? and? it not? work? after

it is? the same? ?here

if? you? work? whit? iron? you modify? the? power of? mag? of? the 2? ?part??
and? it is? not? blance? after? ??

jack 47 71
 

Actually, use non-magnetic tools - there are things other than brass that are non-magnetic! I'm fond of getting a bag of popsicle sticks from a craft store & shaping them into useful tools. There are also a bunch of useful plastic tools made for working with adhesives.

Roy
 

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Old steel or alloys (AlNiCo for example) magnets used on car, bike or telephone magnetos, galvanometers, ...? were easily losing their field strength when decoupled from their armatures or when shocked or annealed. Modern ones e.g. Neodymium are far more strong, they almost don't or, at least insignificantly do.

Consequently, from time to time or mandatorily if dismantled these magnetic fossils were needing a re-magnetization that nowadays can easily be done. It's a matter of Ampere x turns.

Here's a link that will make Jacques' life, otherwise for English people googletrans is your friend !

This is only a piece of public information, not a how-to procedure. Of course, it's up to you to protect yourself. I'm not responsible of any kind of accident that might occur.


On 15.04.24 02:55, Ralph Hulslander via groups.io wrote:

Why would taking it apart lose most of the charge?

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