RE: CS>Magnets & Gauss measurement

[Neville Munn]

Oops, boo boo...We need an 'edit' facility here .  I meant to say 
"restricTed area".
 


From: one.red...@hotmail.com
To: silver-list@eskimo.com
Date: Tue, 16 Nov 2010 22:59:47 +1030
Subject: CS>Magnets & Gauss measurement




Anyone know anything about the Gauss measurement of magnets?
 
Specifically, magnets out of a microwave magnetron.  As one would be aware if 
familiar, those magnets are like a donut, or a very thick washer in shape.
 
I'm interested in the Gauss measurement of the *inside* of the hole in the 
centre.  Don't know if that measurement would be the same as either the north 
or south pole of the faces of the magnet.
 
Secondary to the above...would the centre hole be distinctly north or south in 
polarity, or would that be impossible to determine due to the fact that it's a 
hole, or circular in shape?  Or a combination of both in such a restriced area?
 
Anyone got any idea of what the Gauss meter reading would be?
 
My query *IS* in relation to EIS/CS by the way...{experimental}.
 
N.
  

Re: CS>Magnets & Gauss measurement

[Saralou]

Neville,

Unless  how it's magnetized (axially, diametrically, etc 
http://www.kjmagnetics.com/magdir.asp) is standard on microwave 
magnetron magnets, I don't know how you can tell gauss.  I have a large 
(10" diameter) thick (1.25") speaker magnet that's hollow in the 
middle.  My compass nor my +/- magnets are much help in determining 
which way things flow so I leave it on the dryer with the berkey on top.


There is a magnetic viewing film 
(http://www.kjmagnetics.com/products.asp?cat=154) that would allow you 
to see the direction of magnetization. Perhaps measuring pull would give 
you a clue about the gauss. There's some interesting reading regarding 
gauss at K & J. http://www.kjmagnetics.com/FAQ.asp


Yes, there are other magnet companies, I just happen to have read the 
info from this company.


Saralou


other interesting links

http://www.kjmagnetics.com/blog/index.php/2010/01/04/surface-fields-101/
http://www.freepatentsonline.com/5177403.html
http://www.repairfaq.org/REPAIR/F_micfaq2.html


Don't know how accurate this is 
http://www.sas.org/E-Bulletin/2002-10-25/labNotes/body.html


   25 October 2002

   *Sources of Extremely Powerful Magnets*

   Source: Sam's Gadget FAQ
   

   Two excellent sources of magnets are described below. These are at
   least as strong as the more well known speaker types, possibly much
   stronger, and generally easier to remove:

   * Microwave oven magnetron tubes. Go to your local appliance
 repair shop and ask - they just toss bad ones. Each one has
 two ring shaped ferrite magnets about 2-1/4" in diameter with
 a 7/8" hole, magnetized N-S on the faces.

 Surplus places typically charge $3 to $6 each for one of these
 magnets.

 Note: A few older magnetrons used AlNiCo magnet assemblies or
 even possibly electromagnets which are not nearly as
 interesting. However, you probably won't see any of these.

   * Large hard disk drives - especially full height 5-1/4" high
 performance types - e.g., Seagate WREN series or Micropolous
 boat anchors (the rare earth magnets in these are wicked). The
 magnets in small drives are even stronger but are, well, much
 smaller. :-) A typical size for a large drive is about 1" x
 1-1/4" by 1/2". Since almost no one wants such large slow
 drives anymore, they are often found at swap meets or yard
 sales for next to nothing. These magnets are a few thousand
 Gauss compared to 10 to 15 K Gauss (1 to 1.5 Tesla) for a
 medical MRI scanner (of course, the field of the MRI scanner's
 superconducting magnet is uniform over a volume of several
 cubic FEET! The disk drive magnet's field decays quickly as
 you move away from it.)

 Surplus places may charge $12 or more for ONE of the magnets
 from a large disk drive (there are typically 2 to 6 such
 magnets in a disk drive)!

 I have a monolithic clump of 40 or 50 of the magnets from full
 height 5-1/4" SCSI drives. I figure there is a black hole
 growing inside but haven't dared to look. :) The only way I
 was able put the clump together with minimal damage to flesh
 was by using a hard wood ramp to gently guide each new magnet
 into place. I haven't figured out how I'll ever get them apart
 though!

 Here is a quick easy experiment to try with these powerful
 magnets: Slide one such magnet over a thick aluminum plate.
 What do you feel? Or, let a 1/8" x 2" x 12" aluminum plate
 drop through the intact yoke from a Seagate WREN series 5-1/4"
 full height hard drive positioner. What happens? Why? What
 material might produce an even more pronounced effect? Why?

 For more things to do with these neat magnets, see:
 Neodymiumarium .

   CAUTION: Both these types are powerful and will squash flesh as they
   suck all the bits off of your magnetic media! I am not kidding about
   the part about squashed flesh - with some you actually need a small
   crowbar to pry the assembly apart!

   You will find that some of these magnets are painted. This provides
   some resistance to chipping though this material may be on the verge
   of flaking off or has already done so in spots. In any case, I
   further recommend that you add additional layers of a tough enamel
   (e.g., Rustoleum) or the plastic/rubber dip used to coat tool
   handles. Otherwise, chipping damage (at least) will result all too
   easily and the chips are just as powerful as the rest of the magnet.

   Additional Disclaimer: I will not be responsible when your spouse or
   parents come home to find the microwave or PC missing some key
   components and as dead as a brick!

   (From: Terry Sanford (tsanf...@nf.sympatico.ca)

RE: CS>Magnets & Gauss measurement

[Neville Munn]

Thanks very much for that Saralou.
 
It'll take me a while to go through all that information so I'll express my 
gratitude now .
 
I do know that these microwave magnets damage very easily.
 
And a mate of mine had a couple of relatively powerful magnets.  He had me in 
hysterics when he said that if he had one in his pocket he could never get past 
the steel workbench in his shed.  Then he pinched the fingers on his hand when 
they both slammed against each other.  Not funny really I spose, but have to 
say it was hilarious at the time.
 
It's so easy not to appreciate the power in some of the more powerful magnets 
when one is only used to handling the more piddly ones.
 
Cheers
 
N.
 
> Date: Wed, 17 Nov 2010 22:52:42 -0500
> From: slped...@gmail.com
> To: silver-list@eskimo.com
> Subject: Re: CS>Magnets & Gauss measurement
> 
> Neville,
> 
> Unless how it's magnetized (axially, diametrically, etc 
> http://www.kjmagnetics.com/magdir.asp) is standard on microwave 
> magnetron magnets, I don't know how you can tell gauss. I have a large 
> (10" diameter) thick (1.25") speaker magnet that's hollow in the 
> middle. My compass nor my +/- magnets are much help in determining 
> which way things flow so I leave it on the dryer with the berkey on top.
>