[Boatanchors] Need magnetic shield for shaded pole motor

[J. Forster]

The problem with mu-metal is that machining (cutting & bending) destroys
its magnetic shielding properties. There is another shielding material,
called Netic-Conetic that is more forgiving.

Copper is OK, provided it's several skin depths thick.

I do agree that coffee cans are a bit on the thin side. If you can find a
tin-plated-steel can of heavier guage, go for it. A source might be the
larger 'family size' soup cans or the dumpster behind a resteraunt.

The tin plating is mostly a rust preventative. A light coat of clear
Krylon will do fine.

-John

===============

> Jim,
>
> Non-ferrous metals, copper etc., will do little to attenuate a magnetic
> field. There is an alloy, know an mu-metal, that was designed just for
> such applications, but it's expensive and hard to come by. Google same.
> Start here:
> http://www.pmlindia.com/hi-perm/Magnetic-Shield.htm?gclid=CJ3ghvWc4LsCFTNp7AodLUsAmA
>
> However, mu-metal only has a slight edge over soft iron or even steel.
> The coffee can may be a little too thin. The wreckage of a LARGE
> transformer may be the place to start.
>
> Al
>
> On 1/2/2014 2:22 PM, Charlie , W5COV wrote:
>> I keep some handy copper sheets on hand all of the time now, comes in
>> handy for various projects. This that I keep on hand, can be cut with
>> scissors, and is relatively cheap, as am I <grin> .
>>
>> I picked it up from a from a place called Electronics Goldmine.
>> http://www.goldmine-elec-products.com/
>>
>> Really handy to have around.
>>
>> Usual disclaimer no financial interest, just a satisfied customer.
>>
>> Charlie, W5COV
>>
>> On 1/2/2014 1:14 PM, rbethman wrote:
>>> Use either the cut up coffee can as John suggests, they ARE becoming
>>> another rarity.
>>>
>>> Now the coffee is coming in plastic containers. :^(
>>>
>>> Copper is still available as a roofing/flashing item in the Home
>>> Improvement stores.
>>>
>>> I have procured some silver plated copper expanded mesh some years
>>> back.
>>>
>>> It was offered on one of the mailman.qth.net lists. It may have been
>>> this one or it may have been the glowbugs list.
>>>
>>> Bob - N0DGN
>>>
>>> On 1/2/2014 11:33 AM, J. Forster wrote:
>>>> A cut up coffee can? Seriously.
>>>>
>>>> -John
>>>>
>>>> ============
>>>>
>>>>
>>>>> Any ideas for an effective Gaussian shield for an open frame shaded
>>>>> pole
>>>>> motor or a source for very high permeability transformer core uncut
>>>>> sheets.
>>>>>
>>>>> Thanks for any ideas--- Kindest regards Jim K9AXN
>>>>>
>>>
>>
>
> --
> Al Klase – N3FRQ
> Jersey City, NJ
> http://www.skywaves.ar88.net/
>
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