Magnatism issue

[kd8tzc]

Yesterday, I was practicing on a spare Seiko 7S26 movement that I have, and I had already demagnetized the watch prior to working on it, but the small screws that I was working with on the movement would stick to my tweezers.  I thought for a movement either the screws were still magnetized, or the tweezers were.  I demagnetized both (put the screws in a small plastic movement box) tried again, but still the same issue. 

Any ideas what to do?  This was driving me nuts.

[ColdWind]

What kind of demagnetizer do you use? Is this the first time you use it?

[kd8tzc]

I have the cheap Chinese one (blue with red button).  I know it works as I had a watch that was magnetized (tested with Lepsi for whatever that may be worth) and when I used the demagnetizer on it, Lepsi did not detect magnetism after.  I doubt it is as good as the pro demag units, but I'm just a hobbyist.

[oldhippy]

De mag all the tools that you are using for this movement and the whole movement and the screws again are you sure the screws are clean if not clean them. I had one of those demagnetizers never had any problem, I think they are around £15 so how much did you pay?

[HectorLooi]

I had a defective demagnetizer. The unit was wired wrongly and it stopped working after a few uses.

I took it apart and the wiring didn't make sense. The LED was wired in series with the coil, with all the current going through it. I rewired it and changed the LED and it has been working very well since.

When you press the little red button, does the LED light up and the object that you are trying to demagnetize stick to the unit and buzz in your hand. If it does, then the unit is working fine. 

When you press the button, draw the object that you are demagnetizing away perpendicularly from the surface and do not release the button until it is at least 12 inches away.

And like @oldhippy said, make sure the parts are clean and oil free. Tiny parts can adhere to your tweezers if there is oil on them.

[Neverenoughwatches]

11 hours ago, kd8tzc said:

I have the cheap Chinese one (blue with red button).  I know it works as I had a watch that was magnetized (tested with Lepsi for whatever that may be worth) and when I used the demagnetizer on it, Lepsi did not detect magnetism after.  I doubt it is as good as the pro demag units, but I'm just a hobbyist.

A phone app may not be the best indicator for magnetism. I wouldnt rely on the small compasses either as the tip of the needle needs to be magnetic to actually work as a compass. So Something with a certain degree of magnetisable mass like tweezers could pull on the compass needle indicating a small amount of magnetism. Maybe back to basics and find a small rod of carbon steel that you know for sure is free of magnetism through trial and error on some different screws. Then use this to test for magnetism on the screws you think have become magnetised. I also have the cheap blue chinese demagnetiser, they do work perfectly if as Hector says is wired correctly . I've demagnetized tiny dial screws effectively with it. I did have frequent issues with magnetism and figured my computer was too close to where i was working. Moved it 3 feet away onto a different bench now no issues. The blue rubber bench mats that beginners sometimes buy  do come in magnetic versions .

[JohnR725]

13 hours ago, kd8tzc said:

I have the cheap Chinese one (blue with red button).  I know it works as I had a watch that was magnetized (tested with Lepsi for whatever that may be worth) and when I used the demagnetizer on it, Lepsi did not detect magnetism after.  I doubt it is as good as the pro demag units, but I'm just a hobbyist.

 

2 hours ago, HectorLooi said:

When you press the button, draw the object that you are demagnetizing away perpendicularly from the surface and do not release the button until it is at least 12 inches away.

the key to success with any tool is understanding how to use it properly. Like the directions above will lead to success.

1 hour ago, Neverenoughwatches said:

A phone app may not be the best indicator for magnetism. I wouldnt rely on the small compasses either as the tip of the needle needs to be magnetic to actually work as a compass. So Something with a certain degree of magnetisable mass like tweezers could pull on the compass needle indicating a small amount of magnetism.

I thought the phone apps would actually be quite good as they're looking for magnetic fields not iron objects. The compass has a minor little problem of it is a magnet and magnets are attracted to iron items whether there magnetized or not.

 

 

[kd8tzc]

Yes, parts (and tools) are clean, yes I know the blue box works as I hear it hum and parts dance around if they are small and in a container.  Yes, I pull the parts away when I press the button.  Very odd as these three screws are the only parts that seems to have an issue.

I'll keep messing around with it.  I have a few neodymium magnets that possibly I can magnetize something with and see if it will demag okay.  Not sure what else to try.

On a side note, when I demag the tweezers, they vibrate like a tuning fork... very cool. 

Edited April 19, 2023 by kd8tzc