[Boatanchors] Need magnetic shield for shaded pole motor

[J. Forster]

That roughly agrees with what I remember.  The relative incemental
permeability does not go to 1, of course, but it doesn't stay in the 10s
of thousands either.

Annealing involves heating the finished part (maybe in a H2 furnace
reducing environment) to near red heat then cooling slowly. That seems a
bit beyond a home hobby shop.

Tin can stock seems a simpler solution.

YMMV,

-John

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> On 1/2/2014 2:50 PM, J. Forster wrote:
>> 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.
>
> Perhaps better to say it degrades it, John.  Any physical deformation,
> even dropping it on a sharp edge, can cause problems. It has to be
> annealed after forming, so a heat treat operation is in order following
> fabrication of the shield structure.
>
> At least that's what I recall from working with the stuff back in the
> dark ages.
>
>      73,
>   - Mike
>
>
>