Chinese clone demagnetizers

[Levine98]

Hi,

I’m thinking about upgrading my demagnetizer and wanted to check to see if anyone has experience (good or bad) with the Chinese knockoff of the Elma demagnatizer.
At present I use the cheap blue job on watch movements and while a tad clunky it seems to work OK for movements. However it doesn’t really handle tools and other larger pieces (like my anvils which are very magnetized) particularly well.

i also have a US made K&D demag unit but have put it aside permanently re: it is so strong I can’t hold the tools, anvil whatever stable enough while passing the piece through the donut hole and ultimately the piece ends up more magnetized then when I started.

Feedback would be most welcome since I can’t justify the $299 for a Elma unit but can spring $49 for a Chinese knock off.

 

thanks jay 

 

[RichardHarris123]

Find a plastic tube, cut longer than the K&D, put your tools etc in it and hold both ends.  The plastic shouldn't have any effect. 

[Levine98]

3 hours ago, RichardHarris123 said:

Find a plastic tube, cut longer than the K&D, put your tools etc in it and hold both ends.  The plastic shouldn't have any effect. 

Sounds interesting but how do you push the button if you’re holding both ends?

the large current draw overheats after 3-5 seconds and the thermister triggers. A great tool for magnetizing things but I’ve not be able to ever demag anything with it because the emf is so strong it pulls the item off center (down or up).

 

I paid $89 bucks for it from  CAS-KER, if someone on the board wants it I’d gladly sell it for $25 plus shipping (probably US only otherwise postal costs are prohibitive). Just sent me a note offline.

Edited May 8 by Levine98

[HectorLooi]

My mentor has been using one of the Chinese clones for several years. Seems to work very well. Just put the object you wish to demagnetize in the centre of the cross and press the button.

One word of caution though, the quality and QC of Chinese clones can vary a lot. You'll never know whether you got a gem or a lemon.

[nevenbekriev]

10 hours ago, Levine98 said:

Hi,

I’m thinking about upgrading my demagnetizer and wanted to check to see if anyone has experience (good or bad) with the Chinese knockoff of the Elma demagnatizer.
At present I use the cheap blue job on watch movements and while a tad clunky it seems to work OK for movements. However it doesn’t really handle tools and other larger pieces (like my anvils which are very magnetized) particularly well.

i also have a US made K&D demag unit but have put it aside permanently re: it is so strong I can’t hold the tools, anvil whatever stable enough while passing the piece through the donut hole and ultimately the piece ends up more magnetized then when I started.

Feedback would be most welcome since I can’t justify the $299 for a Elma unit but can spring $49 for a Chinese knock off.

 

thanks jay 

 

Demagnetising of an anvil will depend of the anvil size. If it is big, then nither Elma, nor chinese clone will do the job. But the K&D from the picture will do. Have in mind that the bigger is the object, the stronger is the magnetic force that it will fill inside the field. If You can't hold the object still, then You will need demagnetiser that works on higher frequency rather than smaller one.

[Levine98]

On 5/8/2024 at 2:54 PM, RichardHarris123 said:

Find a plastic tube, cut longer than the K&D, put your tools etc in it and hold both ends.  The plastic shouldn't have any effect. 

So I wrapped the anvil it in bubble wrap and passed ot through the demag only. Still no go—the unit is simply too strong. 
next experiment is to use a VARIAC to lower the voltage and see if that reduces the magnetic field. 

[valleyguy]

Clickspring as a video review of the chinese demagnetizer.

 

[VWatchie]

I have the Elma demagnetiser and it works well enough for watch movements. However, it's not powerful enough to demagnetise tools such as hand levers. At least my copy isn't. These days I use a Greiner Magnomatic which I was lucky to get used for just about £100. It works really well with anything which fits in it.

[Waggy]

24 minutes ago, valleyguy said:

Clickspring as a video review of the chinese demagnetizer.

I have the big blue one on the video, the one he is reviewing, and I agree that it does a great job. I purchased sone large non-horology type (but still good quality) screwdrivers 3mm,  5mm, 7mm and so on for clockmaking that were deliberately sold as magnetized ie it was factory applied and sold as a feature. I used my demagnetizer and with one click I saw the screwdriver jump and re-orientate itself slightly on the plate and sure enough they were no longer magnetized.

[VWatchie]

I watched the video review of the Chinese version of Elma's demagnetizer and I am skeptical about the use of a compass to measure magnetism. To measure magnetism I use a metal detector app on my iPhone. There are many such apps and they generally work well. The problem with using a compass is that they are not very sensitive while the apps detect the slightest trace of magnetism.

[Waggy]

16 minutes ago, VWatchie said:

I use a metal detector app on my iPhone

I use the same thing on my android:

Edited Thursday at 07:16 AM by Waggy

[RichardHarris123]

30 minutes ago, Waggy said:

I use the same thing on my android:

How accurate is it? Does it take the earths magnetic field into account, what is an acceptable reading?

[Waggy]

@RichardHarris123 I just look for a relative increase or decrease as it passes over the watch, not an absolute value. It it doesn't change much passing over the watch, than I conclude little or no magnetism, if I see the value jump from the background number, than I know I have a problem

 

Edited Thursday at 07:53 AM by Waggy
Typo

[Zendoc]

I agree - I use a magnetometer app on my iPad.

A few years ago, I did invest in the Elma version of this demagnetiser. I have a background in electronics and when I cracked the unit open to explore it, I was very impressed - and reassured - by the careful attention given to the design and the quality of construction and quality of materials.  It will out-live me, and not because of any shock hazard   I find it very reliable for demagentizing watch movements, but for tools, especially elongated tools like tweezers and screwdrivers, they need to be done in sections, a couple of centimetres at a time.  I always also repeat the demagentising process several times with the object (usually a movement) oriented in several different planes - horizontally at 0 and 90 degrees and vertically.  Checking on the magnetometer app, the movement is effectively degaussed and I’ve not yet had to repeat the process. Just laying the movement horizontally and giving it a single shot sometimes works, but often doesn’t, hence my process above.  Using a compass, I doubt I’d ever know whether the process was effective or not.  The magnetometer is much more sensitive. I still use the Lepsi app, which was available for free, but which I don’t think is  available on the App Store any more.  

 

[RichardHarris123]

For larger or longer components I have a home made demagnetiser, a old central heating pump with the rotor removed, works well. 

[watchweasol]

I have a DIY version, it’s a voice coil from a 300mb disc drive and a vdu transformer , when you put the tweezers in they vibrate like a tuning fork  and come out clean. Could get an engine block in.

[Waggy]

17 minutes ago, watchweasol said:

when you put the tweezers in they vibrate like a tuning fork

Ha ha, reminds me of this:

"Don't go puttin' none of that stuff on my sled, Clark. You know that metal plate in my head? I had to have it replaced, cause every time Catherine revved up the microwave I'd pi$$ my pants and forget who I was for a half hour or so. So over at the VA they had to replace it with plastic."

[Neverenoughwatches]

1 hour ago, VWatchie said:

I watched the video review of the Chinese version of Elma's demagnetizer and I am skeptical about the use of a compass to measure magnetism. To measure magnetism I use a metal detector app on my iPhone. There are many such apps and they generally work well. The problem with using a compass is that they are not very sensitive while the apps detect the slightest trace of magnetism.

I bought a compass to detect magnetism. The magnetic tip reacted to both magenetised and non magnetised basic steel so it became a guessing game as to whether my test subject was either weakly magnetised or dense steel. I've found the best way to detect magnetism is by using the smallest unmagnetised screw and a known piece of unmagnetised steel to test the screw and another piece of known unmagnetised steel to test the first known piece of unmagnetised and another.......................  

[Waggy]

13 minutes ago, Neverenoughwatches said:

The magnetic tip reacted to both magenetised and non magnetised basic stee

I can remember in the army, doing a tactical night march and the officer leading the march had the bright ide of taping his compass (with tritium tipped hands) to the end of the barrel of his rifle so he could get a better bearing in the dark. We ran around in circles for hours until he realized that the compass was reacting to the steel of the rifle barrel. To say he was unpopular was a bit of an understatement.

[Neverenoughwatches]

15 minutes ago, Waggy said:

I can remember in the army, doing a tactical night march and the officer leading the march had the bright ide of taping his compass (with tritium tipped hands) to the end of the barrel of his rifle so he could get a better bearing in the dark. We ran around in circles for hours until he realized that the compass was reacting to the steel of the rifle barrel. To say he was unpopular was a bit of an understatement.

Thats why i never joined the army scott

[tomh207]

34 minutes ago, Waggy said:

I can remember in the army, doing a tactical night march and the officer leading the march had the bright ide of taping his compass (with tritium tipped hands) to the end of the barrel of his rifle so he could get a better bearing in the dark. We ran around in circles for hours until he realized that the compass was reacting to the steel of the rifle barrel. To say he was unpopular was a bit of an understatement.

Which is why we never gave a map or compass to the bloody Rodney’s!

 

Tom

[RichardHarris123]

Luddites, what's wrong with SatNav?

[VWatchie]

52 minutes ago, Waggy said:

We ran around in circles for hours until he realized that the compass was reacting to the steel of the rifle barrel.

That's exactly why you need to exercise, or you'll meet with an untimely death! 

40 minutes ago, Neverenoughwatches said:

Thats why i never joined the army scott

Well, good thing you weren't born in my neck of the woods then as you would have no choice.

Back in the day when it was time for my service (early 80s) this small country could mobilize 800,000 soldiers in a few days, and mobilization supplies with modern weapons and munitions were everywhere and we had an air force second to none. Then beginning in the 90s it was scrapped because our politicians decided that Russia would become a Western democracy. In discussions with colleagues, friends and acquaintances where I mentioned I thought it was imprudent to scrap our capacity for self-defense, I was laughed at. I wonder if anyone of those people would laugh today.

[Neverenoughwatches]

16 minutes ago, VWatchie said:

That's exactly why you need to exercise, or you'll meet with an untimely death! 

You know it H

19 minutes ago, VWatchie said:

That's exactly why you need to exercise, or you'll meet with an untimely death! 

Well, good thing you weren't born in my neck of the woods then as you would have no choice.

Back in the day when it was time for my service (early 80s) this small country could mobilize 800,000 soldiers in a few days, and mobilization supplies with modern weapons and munitions were everywhere and we had an air force second to none. Then beginning in the 90s it was scrapped because our politicians decided that Russia would become a Western democracy. In discussions with colleagues, friends and acquaintances where I mentioned I thought it was imprudent to scrap our capacity for self-defense, I was laughed at. I wonder if anyone of those people would laugh today.

Ours was scrapped early 60s. Nothing wrong with joining the army H , i would have love the physical and discipline side of it, but i can't follow or be lead by numpties.

[VWatchie]

As a child/young person, I remember how the police sometimes appeared in the middle of a country road and blocked off the traffic. A few minutes later, a fighter jet flew over our heads (loudly and respectfully, almost making us crap our pants), landed in front of us and was towed into the forest. It made us feel safe.

I just realized that I've come a long way from demagnetizing watch movements, but isn't that the charm of associations and discussions? Anyway, I'll stick to the topic from here on!

26 minutes ago, Neverenoughwatches said:

Ours was scrapped early 60s.

Yeah, we decided to stop developing nukes in the late 50s and spend the money on conventional weapons instead. Oops, sorry moderators, I seem to have a problem controlling myself. No more now. I promise.