cutting MUMETAL shields

rafafredd

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I have some big MUMETAL boxes in here and I would like to use it as mic input trafos shields.

Is there any problem in cutting those?

There´s no need to BEND this, just to CUT. I´m thinking about doing 8 pieces in form of C for 4 trafo shields. Will I just waste the permeability properties if I try it?
 

Michael Krusch

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As I understand it: Every action that harms the internal structure of the mu-metall will bring down its sheelding ability. And cutting will harm that structure at leased at the cutting edges.
Normaly you have to bring that metall in the right shape and then it needs to be processed at high temperature to become mu-metall.
 

ChumpitO

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[quote author="Michael Krusch"]As I understand it: Every action that harms the internal structure of the mu-metall will bring down its sheelding ability. And cutting will harm that structure at leased at the cutting edges.
Normaly you have to bring that metall in the right shape and then it needs to be processed at high temperature to become mu-metall.[/quote]

Then what would be the usefulness of mu-foil? Is it no good?

I was planning on just making sheilds from soft iron bent into boxes and line it with both tin and copper shielding tape as I havn't found a cheap source for mu-metal and I can get the tape for around $1/roll.
 

ChumpitO

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Oh yeah..... if I just use foil tape and use several pieces do you guys know if they have to make electrical contact with each other, if so do you know why?
 

CJ

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You could do a three piece can with brass or copper inserts to get a good shield.
I don't see the metal changing much,I mean it'snot like re arranging the domains of a magnet by hitting it with a hammer?
Look at your transformer response with and without the can to make sure you are not altering the curve too much.
Stray flux gets induced into the can somewhat. I mean they do make core lams out of mu metal, so it will absorb a little flux
Maybe its the capacitance to ground. I d not know but am currently looking into this phenomenaomanemn.
.
cj
 

rafafredd

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Well, in fact I would like to do it to use with DIY mic input trafos, so I think I need mumetal cans.
 

Dan Kennedy

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Jun 5, 2004
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I use semi-annealed mu-metal as moderate level shielding all the time. I cut, bend, and solder it, it still is much better than cold rolled steel. If you're cutting material from some existing thing, it's probably been annealed after
it was formed, so it has maximum effectiveness. You're further working of it isn't likely to hurt it much.
 

tommypiper

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I hadn't seen this thread and just started another one on mu-metal...

What's a good source for buying mu-metal in small parts for our transformer shielding applications, in the US?

cheers,
t
 
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