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Author Topic: Magnetic Shielding  (Read 30091 times)

CLaNZeR

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Magnetic Shielding
« on: October 03, 2006, 12:16:00 PM »
Has anyone played with shielding materials such as MetGlas?

http://www.blockemf.com/catalog/product_info.php?cPath=757&products_id=5114

Looking here http://www.lessemf.com/faq-shie.html#Lead-Copper they quote the following:

Here's how the permeabilities of some common materials compare:

Air ........... 1
Copper ...... 1
Aluminum ... 1
Tin ............. 1
Lead .......... 1

Nickel .................. 100
Commercial Iron ... 200
Stainless Steel ....... 200
MagnetShield ........ 4000

Magnetic Shielding Alloys* ....... 20,000+
Annealed MetGlas ................. 1,000,000

Regards

Sean.


CLaNZeR

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Re: Magnetic Shielding
« Reply #1 on: October 22, 2006, 10:30:30 PM »
No replies on this one, so have ordered 10ft length to see if it will get over the sticky point.

Will post the results.

Regards

Sean.

thevorlon

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Re: Magnetic Shielding
« Reply #2 on: October 22, 2006, 11:40:44 PM »
Could you give us an example of where exactly on a magnetic motor would you be placing this insulating material? Where exactly is the spot that you are trying to insulate?

I look forward to hearing your results.

CLaNZeR

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Re: Magnetic Shielding
« Reply #3 on: October 23, 2006, 12:00:11 AM »
The easiest way is to look at simple wheel designs such as this that show shielding

http://www.fdp.nu/otherwheels/bartosz.asp?URL=bartosz.asp

Not saying it will work, but the logic is there.

Regards

Sean.



Could you give us an example of where exactly on a magnetic motor would you be placing this insulating material? Where exactly is the spot that you are trying to insulate?

I look forward to hearing your results.

thevorlon

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Re: Magnetic Shielding
« Reply #4 on: October 23, 2006, 12:09:34 AM »
Ever consider building some Halbach arrays to put on the rotor? They amplify their magnetism on one side and cancle it on the other. It could *perhaps* help with these sticky points.

http://www.matchrockets.com/ether/halbach.html

CLaNZeR

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Re: Magnetic Shielding
« Reply #5 on: October 23, 2006, 12:23:08 AM »
Now thats interesting and easy enough to try out.
Thanks for the link.

Regards

Sean.


Ever consider building some Halbach arrays to put on the rotor? They amplify their magnetism on one side and cancle it on the other. It could *perhaps* help with these sticky points.

http://www.matchrockets.com/ether/halbach.html

CLaNZeR

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Re: Magnetic Shielding
« Reply #6 on: November 04, 2006, 09:44:43 PM »
Just to let you know.

The material arrived, cost a fortune, delivery from USA to UK was more than the material, Customs hammer you a extra 17.5% and at the end of the day you get a roll of 1 inch tin foil that seems to have as much magnetic shielding as a piece of paper LOL

They state in the instructions that you can even wrap your magnets in it, why??? it makes no difference !!!

Do not waste your money, I have played with this material all week, from making a sandwich to keep the air space in the equation to wrapping a whole coil in the stuff.
I see no shielding here of magnetic fields at all, maybe ideal for distant shielding of speakers etc etc but as far as trying to divert the magnetic field to weaken it, a waste of time.

Well you learn and onto the next experiment!

Regards

Sean.


konduct

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Re: Magnetic Shielding
« Reply #7 on: November 04, 2006, 09:54:52 PM »
How big are the magnets you are trying to shield?  Neo / Ferrite?

CLaNZeR

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Re: Magnetic Shielding
« Reply #8 on: November 04, 2006, 10:04:24 PM »
I have tried every magnet I have here, and that is a lot of different sorts LOL

The weakest ones I have are ferrite typical kidz magnets Painted Red at one end and struggle to pick up a washer! and even wrapping a layer of this stuff with a fair of bit of air space the field is very prominent.

Have tried various lengths to try divert the field but still seems the same. The only insteresting thing I did find was by playing a small strip on the end of my magnetic spiral wheel, the kick back did seem to increase.
Will go back and play some more when I get time, at the moment, got yet another wheel on the milling machine!!

Regards

Sean.



How big are the magnets you are trying to shield?  Neo / Ferrite?

djancak

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Re: Magnetic Shielding
« Reply #9 on: November 04, 2006, 10:08:02 PM »
Thanks for the warning. I think perhaps you should post this warning in the "fraudulent offers" section of the forum too.

Just to let you know.

The material arrived, cost a fortune, delivery from USA to UK was more than the material, Customs hammer you a extra 17.5% and at the end of the day you get a roll of 1 inch tin foil that seems to have as much magnetic shielding as a piece of paper LOL

They state in the instructions that you can even wrap your magnets in it, why??? it makes no difference !!!

Do not waste your money, I have played with this material all week, from making a sandwich to keep the air space in the equation to wrapping a whole coil in the stuff.
I see no shielding here of magnetic fields at all, maybe ideal for distant shielding of speakers etc etc but as far as trying to divert the magnetic field to weaken it, a waste of time.

Well you learn and onto the next experiment!

Regards

Sean.



CLaNZeR

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Re: Magnetic Shielding
« Reply #10 on: November 04, 2006, 10:16:08 PM »
Well I do not know if we need to go that far.
It probably does well in shielding interference if you wrapped a cable in it but for what I want to use it for, a waste of time !!!!!

Show me a shield that can be layed on top of a magnetic pole, whatever shape, that will divert the field back around to the opposing pole, with the external side not effected by the field, then I will get excited, but I have not so far seen this claim and trying other materials that may do the job on fluke as such!!.

Regards

Sean.

Thanks for the warning. I think perhaps you should post this warning in the "fraudulent offers" section of the forum too.

Just to let you know.

The material arrived, cost a fortune, delivery from USA to UK was more than the material, Customs hammer you a extra 17.5% and at the end of the day you get a roll of 1 inch tin foil that seems to have as much magnetic shielding as a piece of paper LOL

They state in the instructions that you can even wrap your magnets in it, why??? it makes no difference !!!

Do not waste your money, I have played with this material all week, from making a sandwich to keep the air space in the equation to wrapping a whole coil in the stuff.
I see no shielding here of magnetic fields at all, maybe ideal for distant shielding of speakers etc etc but as far as trying to divert the magnetic field to weaken it, a waste of time.

Well you learn and onto the next experiment!

Regards

Sean.



Liberty

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Re: Magnetic Shielding
« Reply #11 on: November 04, 2006, 10:37:00 PM »
I see you all are talking about magnetic shielding. 
Shielding and total flux shorting are two different things.
I have found that if you use netic instead of conetic, it works better with near direct magnet contact.  When you shield a magnet, you do not want the shield to touch the magnet.  Layers that are separated work better at shielding magnetic field than one thicker layer.  If your goal is to conduct flux from a magnet to short it out, a thick piece will be needed.  However, the thicker that you get the netic, the more difficult it is to shape it.  I would suggest that you ask the company that you order it from what the thickest sheet is that you can get, while still being able to shape it.  One layer will not completely shield a magnetic field if you use neodymium magnets.  Multiple layers will reduce it, kind of like using insulation to insulate a building.  The higher the R-factor, the more it will insulate. 

Netic will rust if kept in a humid area.  It comes slightly oiled and is messy to deal with.  I would suggest that when you get it the way you want it, clean it off and use clear coat laquer or something like that to keep the air from rusting it.

Just a few tips.  Hope it helps.

mbell

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Re: Magnetic Shielding
« Reply #12 on: November 04, 2006, 10:39:47 PM »
I am not sure if this is what you are looking for but I have taken the magnets and the magnet shielding out of a computer hard drive and it seems to do pretty good job of at least shielding the magnetic force. The magnet will always attract to the shielding but beyond the shielding there is no attraction or repulsion.

Mike

CLaNZeR

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Re: Magnetic Shielding
« Reply #13 on: November 04, 2006, 10:59:30 PM »
Many thanks for the tips Liberty, well appreciated.

I have tried many different configs with this material this week, inlcuding sandwiching it between layers of different material from wood to vinyl. Various spacing from the magnets etc etc.

If I am honest I do not see any difference, so will leave it on the back burner and move onto the next thing onthe ToDo list !!

Regards

Sean.


I see you all are talking about magnetic shielding. 
Shielding and total flux shorting are two different things.
I have found that if you use netic instead of conetic, it works better with near direct magnet contact.  When you shield a magnet, you do not want the shield to touch the magnet.  Layers that are separated work better at shielding magnetic field than one thicker layer.  If your goal is to conduct flux from a magnet to short it out, a thick piece will be needed.  However, the thicker that you get the netic, the more difficult it is to shape it.  I would suggest that you ask the company that you order it from what the thickest sheet is that you can get, while still being able to shape it.  One layer will not completely shield a magnetic field if you use neodymium magnets.  Multiple layers will reduce it, kind of like using insulation to insulate a building.  The higher the R-factor, the more it will insulate. 

Netic will rust if kept in a humid area.  It comes slightly oiled and is messy to deal with.  I would suggest that when you get it the way you want it, clean it off and use clear coat laquer or something like that to keep the air from rusting it.

Just a few tips.  Hope it helps.


CLaNZeR

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Re: Magnetic Shielding
« Reply #14 on: November 04, 2006, 11:03:50 PM »
Hi Mike

I read this in a previous post and it got me interested.
In the previous post they were saying that this shield was found in the old 5.25 Drives rather than the modern 3.5" drives that I have plenty of laying around.
What drive did you pull this out of?

Also I would be interested in knowing how easy the material can be pulled away from a magnet when sliding it rather than pulling?
Also if you form a air gap between this material and the magnet, does it still shield?

Where abouts on the Hard Drive is this material used?

Regards

Sean.

I am not sure if this is what you are looking for but I have taken the magnets and the magnet shielding out of a computer hard drive and it seems to do pretty good job of at least shielding the magnetic force. The magnet will always attract to the shielding but beyond the shielding there is no attraction or repulsion.

Mike