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NNTP-Posting-Date: Fri, 20 Sep 2024 21:07:37 +0000
From: Joe Gwinn <joegwinn@comcast.net>
Newsgroups: sci.electronics.design
Subject: Re: Magnetic force
Date: Fri, 20 Sep 2024 17:07:37 -0400
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On Fri, 20 Sep 2024 12:26:44 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

>On 9/20/2024 9:38 AM, Joe Gwinn wrote:
>> On Fri, 20 Sep 2024 00:11:05 -0700, Don Y
>> <blockedofcourse@foo.invalid> wrote:
>> 
>>> I have an optically-couple "supervisory port" on my
>>> devices.  A design requirement is that the outer surfaces
>>> of the devices must be "wipe clean" -- no ridges or
>>> grooves.
>>>
>>> I mechanically attach the mating "cable" to the port
>>> magnetically (an idea I stole from designing electric
>>> power meters -- but, they aren't "wipe clean"!)
>>>
>>> As I can't rely on any significant mechanical structures
>>> to help maintain the attachment's position, that must
>>> be guaranteed solely by the strength of the magnetic
>>> bond.
>> 
>> This approach will attract and hold magnetic debris, like rust and
>> iron filings.  Is that a problem, or is wiping enough?  If the magnets
>> are strong enough, debris removal may be difficult to do in practice.
>
>Are you expecting the non-magnet surface to assume a
>magnetic state, over time?

Not if the non-magnet side is soft enough magnetically.


>The actual magnet will be on the cable end so the
>"wipe clean" surface will not inherently be magnetized.
>And, the cable end should be easier to manipulate, "scrub",
>etc (even REPLACE) as it is "portable".

That'll work so long as the magnet isn't too strong.

A good way to clean stuff off a magnet pole is adhesive tape.

I'd take a rare earth magnet and roll it around on the floor of the
garage, and see what you catch.

Joe Gwinn