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Magnetism detection with a Compass ...... was I wrong ??


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Referring to the article I wrote last week, regarding suspected magnetism of my movement-holder,

I since learned a few interesting things.

As described in the article, I used a compass to detect magnetism. According to the compass, the movement-holder guide-rails, the circlip and the adjustment-screw were magnetized. And so, according to the compass, were all my Dumont 95% anti-magentic tweezers. I tried to demagnetize all the movement-holder parts and my tweezers with my own made shaded-pole-motor demagnetizer, but the compass needle kept stubbornly showing magnetism.

Doubting my shaded-pole demagnetizer, I set out and build myself another demagnetizer based upon the same principle as the ($$$) Elma demagnetizer; a play between a coil and a capacitor causing a deteriorating magnetic field. The new demagnetizer worked but, according to the compass, the parts stayed stubbornly magnetized. However, all by the compass determined "magnetized"-parts could not lift or did not attract even the smallest iron screw I could find ! ?

So with how much magnetism were my tools actually "magnetized"? According to the compass they were magnetized but in practice the magnetism was not noticeable/detectable.

Discussing this with another forum member, the point was brought forward that the tip of a compass needle is in itself magnetized and therefor the tip of the needle would, when another iron object is held close enough, attract itself to any iron object .......

Testing this I found that indeed any iron object could move the compass needle when held close enough. Unless all the objects I could find were already magnetized, but if not it would make the compass as a magnetism-detection-tool pretty unreliable.  Is it a magnetized object attracting the compass needle or is the compass needle attracting itself to the iron object ?? And at which distance and with which magnetic-field strength does the "change-over" occur? By no way of knowing whether it is the one or the other and the when, the whole idea of using a compass to detect magnetism becomes a very doubtful / confusing / unreliable method. 

Perhaps my movement-holder and the tweezers were not magnetized at all or if so, with how much ?? And how to find out without using a compass and with no physical signs of magnetism detectable ?

Lepsi makes a "watch-magnetism-detection" App for IOS devices (iPhone or iPad). After locating the iPhone or the iPad sensor, it tells you whether a watch or parts thereof, by moving the objects closely over the sensor, are magnetized or not. It gives two indications; "no magnetism" or "magnetism detected", but is doesn't say by how much magnetism if magnetism is detected. There are just the two options; Yes or No.

Funny enough the Lepsi "magnetism-detection" App is to be found in between the "metal-detection" Apps. Do these both Apps work with the same sensor? To find out I downloaded a "metal-detector" App as well.

I've been paying with both Apps and it seems that they both make use of the same sensor. The Lepsi App being more sensitive. The Lepsi App detected at close range magnetism by my movement-holder and tweezers. It also detected at close range magnetism by 9 out of my 10 good running watches ! All my watches are running healthy, with straight lines and do not show any abnormalities on the timegrapher. Of course, nearly all my watches could be magnetized without showing any signs of magnetism !?

How does the Lepsi-App work? If it is based upon the same principle as the metal-detector Apps, at which point or at which sensitivity/threshold does it indicates "magnetism detected"? By no way of knowing the level of magnetism, I've no idea how "bad" things are?

Neither of the two; nor the Lepsi-App nor the iPhone(model?)- or iPad(model?)-sensors are calibrated or have the option to do so. Perhaps the Lepsi-App yields different results depending on the iPhone / iPad sensors-sensitivity. Perhaps my iPhone sensor is one of the sensitive sensors and I gives me "falls Alarm" ??

With the compass being a doubtful magnetism-detection method it seems that with the un-calibrated iPhone & iPad Apps low levels of magnetism detecting becomes close to pure guess work.

Perhaps I was wrong or received the wrong information? Perhaps my tools were/are good enough and do have (if any) such low levels of magnetism that the risk of magnetizing the movement on hand is negligible?

There are no physical signs that any of my tools are magnetized nor that there is any strange behavior of any of my watches. With no physical signs of magnetism, assuming this means low levels of magnetism, it becomes very risky to put a watch on a demagnetizer because a compass or an App say so .... at low levels of magnetism there are too many unknowns and both methods above don't seem to be of any reliable help ......

 

 

 

 

 

 

Edited by Endeavor
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You are right. A compass needle does have its own inherent magnetism so an iron or steel object will affect the needle.

If you were able to swap the ends of the item that you are testing so you would in effect be changing the magnetic polarity, the needle should reverse so its opposite pole is attracted to the item. Going to be extremely difficult with something like a circle. In essence your test of trying to pick something up (smallest screw as you said) is probably a far better indicator.

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Remember a compass is also a small magnet.

If you place a Ferris or item that can be magnetized near the compass the magnet will try to move towards it.

So the compass pointing at is isn't saying it is necessarily magnetized, just that it can be magnetized.

This is why to use a compass you need to walk away from any large Ferris objects, and definitely don't try to use it under or near any high voltage transmission lines.

I agree a compass is of no value to work out if an item is magnetized.

For your screwdrivers and tweezers  if the small watch screws or click springs start to stick to it you need to demagnetize it, else don't worry about it.

 

All good modern phones have magnetometers in them it, works with your GPS to work out which direction you are traveling and what lets those compass apps work when you are standing still as the GPS can only work out direction when you are moving.

 

For the phone apps wait until you accidentally magnetize a screwdriver or tweezers and before you demag them run the app and make comparisons at how close the phone needs to get to them to register any change and compare it to them once demagnetized to give you a simple baseline.

If a watch is magnetized you will know as it will be keeping very bad time and you will likely see hairspring coils sticking together (But check its not just oil on the hairspring first)

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Perhaps back to basic school lessons may be the answer.  ?

Put some iron fillings on a piece of thin paper and put this on something plastic that you can hold over the item being checked. Moving it about should see a pattern in the iron filings develop.  If none then no magnetism in item?

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It's one of the things that always bothered me with using a compass is that of course is attracted to steal. The same steel let's found in watch components which is going to give the impression that everything in the watch is magnetized. Which is why in most professional shops they just demagnetized the watch at least that's what they're supposed to do?

Here's an amusing video. He does show a compass he shows how to use the compass but normally and watch repair the compass we use is supposed to be small. After all were looking for as a guess individual components like a screw and his is just too big.

But he does show something else of interest there is other ways of telling of something is magnetized? I wonder how well those apps really work?

https://youtu.be/DBxeIRnXyXQ

 

 

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Posted (edited)
8 hours ago, JohnR725 said:

But he does show something else of interest there is other ways of telling of something is magnetized? I wonder how well those apps really work?

They do work, kind of. I would prefer the Android App showing the analog meter (Sadly not available in the Apple App-store).

Not that one can count on the numbers given, but al least you get an indication of the magnetism severity.

The Lepsi App gives you only the yes/no indication, depending on the distance of the object held above the sensor. Close enough and a lot of ferrous object will flash the "magnetism detected" sign. In the Lepsi-App setup, to find the sensor position, it shows a number which climbs when you approach the sensor with a magnet. With the Lepsi App the only indication of the magnetism severity is the distance of the object above the sensor at which the App says: "magnetism detected".

I found in the Apple App-store an App called Metal Detector /EMF meter. It shows the iPhone/iPad sensors fields X,Y,Z. Of course nothing is calibrated but it may give you some indication of the magnetic field strength. I'm sure that there are more of these App-types to be found in any of the App-stores.

So yes, they do work ..... "ish" ?

 

Edited by Endeavor
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10 hours ago, JohnR725 said:

they just demagnetized the watch

That's what I do and then I'm simply done with it. These days I never measure the result, in any way, before or after. I tried with those cheap Chinese demagnetizers first but had no luck whatsoever (I believe they are configured for 110V, and I only have 230V 50Hz). So, I got fed up trying and got myself an ELMA ANTIMAG Machine and it has been working perfectly. An investment I have never regretted. I made a video using it for the first time (link below).

I guess the only real reason to demagnetize is if the HS coils are sticking, but I could be wrong about that?

EDIT: In the video I say that I rotate the watch 45 degrees when in fact I rotate it 90 degrees.

Edited by VWatchie
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Posted (edited)
1 hour ago, VWatchie said:

I guess the only real reason to demagnetize is if the HS coils are sticking, but I could be wrong about that?

I wouldn't say for the HS only, but that's a discussion for another thread ?

The Elma demagnetizer may well be the ultimate tool, but for me it's too expensive. We'll see how my own "Elma" will work once completely finished .....

You have the best, so you are set to go ?, me the more el-cheapo mortal has some more road to cover ..... ?

 

 

 

Edited by Endeavor
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20 minutes ago, Endeavor said:

We'll see how my own "Elma" will work once completely finished .....

Well, taking into consideration your many previous achievements, I'd say probably better than the original! ??

Keep us updated!

EDIT: Oh, I'd say that if you have the time and skill to make your own tools, that's always more worthwhile, money or no money!

Edited by VWatchie
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Posted (edited)
1 hour ago, VWatchie said:

These days I never measure the result, in any way, before or after.

If you trust your Elma to its job 100% then that's fine, else you are not quite sure if you did improve the situation or made it worse?

Currently I'm struggling to find a method which does show me the before & after difference. If you, unlike me, don't mind the nervous jumping digital numbers, the Metal detector / EMF meter App (in the Apple App-store) does give you repeatable reference numbers. Find a spot with the highest reading before and compare that with the reading after you "Zapped" your watch or parts thereof.

For me that App would work better if it was displayed in a less nervous analog form, like the one found in the Android store, but it seems to give repetitive numbers and comes for free ...... ?

 

Edited by Endeavor
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I had a HS the other day that just wouldn't demagnetise.  My compass never deviated when passed over the movement which made me think it was contaminated.  I took the HS off a few times and one-dipped it just to make sure it wasn't oil but it was very clean.  Every so often when running you could see a few coils stick together then unstick a bit later.  I must have tried 10 times with my cheap chinese demagnetiser. 

I finally managed it but the time wasted could have been saved with a proper tool.  I'll invest in an Elma.

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I have a Vigor DE-415a.

If you own one, I suggest you put an inline switch rather than leaving it powered continuously.  The design used a Cockroft-Walton multiplier that boosts the mains voltage to a rather large value stored on a 4uF capacitor.  Puts a lot of stress on the cap.  I had to replace the cap and while I was at it, I rebuilt the circuit on a PCB.

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Posted (edited)
39 minutes ago, LittleWatchShop said:

The design used a Cockroft-Walton multiplier that boosts the mains voltage to a rather large value stored on a 4uF capacitor

One has to be a bit careful mentioning voltage-multipliers, particularly where you are on this planet.

In the US the mains are 110V, over here in Europe it's 240VAC. That is 240V DC equivalent. The 240VAC wave-peak lays around 240 * √2 = 340 Volt. If you double that we start talking about a lethal 680Volt which will be stored in the (hopefully high enough rated) capacitor.

Edited by Endeavor
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What I also was trying to say; if you decide for self-build or work on these capacitor/coil demagnetizers, you better know what you are doing ?

 

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7 hours ago, Endeavor said:

If you trust your Elma to its job 100% then that's fine

I do! When testing using the Lepsi app, it was always 100 % consistent. If any indication was present before demagnetizing, it was gone after. So, I feel I no longer need to use the app or any other device to detect magnetism. I simply demagnetize, needed or not,  and then I'm done with it. I trust the ELMA Antimag 100 %

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3 hours ago, AshF said:

I'll invest in an Elma.

You're not going to regret it, and it's really not a fortune even though it is a whole lot of money for such a simple (if I got it right) machine.

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1 hour ago, Endeavor said:

What I also was trying to say; if you decide for self-build or work on these capacitor/coil demagnetizers, you better know what you are doing ?

 

Does an EE Ph.D. (plus adjunct professor and textbook author) qualify?  You are absolutely correct...monkeying around with high voltage is not for the amateur.  Even with my qualifications, I have spent the majority of my career under 50 volts.

Edited by LittleWatchShop
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5 hours ago, AshF said:

I had a HS the other day that just wouldn't demagnetise.

What type of hairspring was this? In other words the classic blued steel hairspring that can magnetize and the supposedly modern not affected by magnetism?

2 hours ago, LittleWatchShop said:

Even with my qualifications, I have spent the majority of my career under 50 volts.

That doesn't seem right the professional should handle the high voltages as opposed to making the technicians do it. Then what's a little high voltage providing it's not too high it's just a painful shock and waking up everybody sleeping in the lab. Then even the rule of one hand in the pocket doesn't work if you don't know where your hand is? Yes playing with high voltages can be interesting.

When I was studying electronics safely applying the one hand in the pocket rule this particular class we were building a microwave transmitter and I needed the measure voltage on the back side of the rack. So my hand this safely on the backside of the rack measuring voltages while I'm looking at the meter on the front side but my arm somewhere between my hand in my elbow touch the grounded frame obviously I wasn't aware of entirely where my hand was. Yes high voltages can be interesting and quite noisy.

4 hours ago, LittleWatchShop said:

Indeed.  It is a 4x multiplier, so that is over 600V here.  They may not sell it in Europe.  I see it is still available here.

Out of curiosity I don't suppose you can get a picture of the inside?

I rather curious about how it looks and its capacitor as compared to the Elma?

 

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21 minutes ago, JohnR725 said:

What type of hairspring was this? In other words the classic blued steel hairspring that can magnetize and the supposedly modern not affected by magnetism?

In the past I have researched on the subject and found that even a leading manufacturer like Seiko does not claim amagnetic properties for their hairsprings. That confirms my experience, these can and do get magnetized. 

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10 minutes ago, JohnR725 said:

Out of curiosity I don't suppose you can get a picture of the inside?

Here it is.

I printed the brackets on 3D printer and made the PCB in my lab. 

There were some "before" pictures, but I cannot find them.

Anybody have inside pictures of the Elma?

2021-04-20 13_23_22-Window.png

2021-04-20 13_23_41-Window.png

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1 minute ago, LittleWatchShop said:

Anybody have inside pictures of the Elma?

I consider the public API of the ELMA to be nothing short of absolute perfection and a source of inspiration. I just don't want to be, nor have an interest in, messing with it's private interface ?

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16 minutes ago, jdm said:

In the past I have researched on the subject and found that even a leading manufacturer like Seiko does not claim amagnetic properties for their hairsprings. That confirms my experience, these can and do get magnetized. 

If you really want to have some fun put a super magnet even a tiny one on top of the Seiko and they hairspring coiled definitely reacts to it. I don't know if the new silicon hairsprings react the same way but all the hairspring seem to be bothered by magnetic fields some degree which seem to be lurking just about everywhere around us with our electronic devices. I notice at work my boss will be timing something and then almost any goes oh I forgot to demagnetized its because he's looking for absolute perfection Annie's noticing and it seems to be better.

This is why in most shops even when I was in school the demagnetizer sitting next to the timing machine or nearby you're supposed to demagnetized. You get really upset us like the previous watchmaker he would demagnetized all of the components when I came out of the cleaning machine you take each individual tray a parts run it across the demagnetizer and probably still demagnetized in the watch was complete.

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