Re: CRT magnetic screens: Mumetal?


Ed Breya
 

That's a good question - I have only used tin snips, which necessarily bend the two sides of the cut. A saw or wheel would be better in that respect. I think a very fine carbide-tipped saw would give the cleanest cut. The material may be soft enough to gum up an abrasive wheel, but I don't know. If you try these methods, please let us know how they work.

I usually assume that any reworked piece will have less than half of its original effectiveness just from handling, and maybe one-tenth near any stressed zones. Even if you beat the hell out of it, it's still at least as good as the original un-annealed material, which I would think is at least as good as steel.

Ed

--- In TekScopes@..., d.seiter@... wrote:

While I've never played with Mu-metal, I have kept all my shields too, knowing about the properties of the material. My question- I know bending and heating affect the metal, but I didn't know that cutting it had an effect. What is the best way to cut it? I'd assume no deflection, so a small cutting disc on well supported stock with coolant would seem to be the best approach?


-Dave

----- Original Message -----
From: "Ed Breya" <edbreya@...>
To: TekScopes@...
Sent: Wednesday, June 19, 2013 4:36:41 PM
Subject: [TekScopes] Re: CRT magnetic screens: Mumetal?






I think in the earlier days, or in some manuals, there were warnings about avoiding stresses on the material. It's not practical to re-anneal to original performance if seriously banged up, but the overall shielding is still pretty good even so, and certainly better than nothing. For our purposes, I wouldn't worry too much about a few dings here and there - just don't put any magnets near the defects, which could become slightly magnetized and possibly cause distortion in the CRT.

I've saved the shields from every CRT item I've ever junked out, and have worked and re-used the material for a number of applications. It loses some of its effectiveness near any cuts or sharp bends, but large planar areas that aren't stressed too much tend to be OK.

Ed

--- In TekScopes@... , "John S" <John@> wrote:


Thanks for the confirmation guys: must have been an expensive component. There's no "warning" lable on either the shield or the manual to tell you not to knock etc.

John

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