• Magnetic force

    From Don Y@21:1/5 to All on Fri Sep 20 00:11:05 2024
    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.

    I have a 1/4" dia glass "jewel" that is just barely convex
    to protect the optical port and support light passage.
    The slight bump helps locate the port as well as some small
    assistance in keeping the mated "cable" positioned properly.

    In no case can the needs of the port exceed a concentric
    diameter of 1/2". I plan for the magnet to only be present
    in the mating cable so its adhesion will be determined by
    the metallic ring surrounding the jewel.

    I figure I need to specify a magnet strong enough to
    "support" (against the force of gravity exerted on the
    mass of the cable) the cable in a horizontal position
    (i.e., "mated to the ceiling"). And, to support the
    cantilevered weight of the cable when mounted
    vertically.

    I may opt to implement the "cable" as a wireless dongle
    if the weight of the cable assembly starts to compromise that
    magnetic adherence.

    I guess I also need to consider the magnetic force exerted
    through the friction between the mating surfaces when
    mounted vertically (so the cable doesn't "slide down the wall")

    Anything else I should consider? I realize that the cable end
    now will have a tendency to want to grab onto metallic objects
    so have to factor that into my dongle vs. cable decision
    (it's a lot easier to control the position of a dongle in
    space than the end of a possibly *dangling* cable!)

    I suspect the adhering "metal" piece has to be on the skin
    of the device as the magnetic field falls off quickly with
    distance -- diluting the ability of the cable to remain
    EXACTLY where desired. A "decal" over the surface likely
    would be tolerable...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to Don Y on Fri Sep 20 09:57:28 2024
    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.

    I have a 1/4" dia glass "jewel" that is just barely convex
    to protect the optical port and support light passage.
    The slight bump helps locate the port as well as some small
    assistance in keeping the mated "cable" positioned properly.

    In no case can the needs of the port exceed a concentric
    diameter of 1/2". I plan for the magnet to only be present
    in the mating cable so its adhesion will be determined by
    the metallic ring surrounding the jewel.

    I figure I need to specify a magnet strong enough to
    "support" (against the force of gravity exerted on the
    mass of the cable) the cable in a horizontal position
    (i.e., "mated to the ceiling"). And, to support the
    cantilevered weight of the cable when mounted
    vertically.

    I may opt to implement the "cable" as a wireless dongle
    if the weight of the cable assembly starts to compromise that
    magnetic adherence.

    I guess I also need to consider the magnetic force exerted
    through the friction between the mating surfaces when
    mounted vertically (so the cable doesn't "slide down the wall")

    Anything else I should consider? I realize that the cable end
    now will have a tendency to want to grab onto metallic objects
    so have to factor that into my dongle vs. cable decision
    (it's a lot easier to control the position of a dongle in
    space than the end of a possibly *dangling* cable!)

    I suspect the adhering "metal" piece has to be on the skin
    of the device as the magnetic field falls off quickly with
    distance -- diluting the ability of the cable to remain
    EXACTLY where desired. A "decal" over the surface likely
    would be tolerable...

    Would a rounded bump on the device be acceptable? A matching hollow in
    the cable end could then locate over it.

    Something like this:
    http://www.poppyrecords.co.uk/other/Connector.gif


    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to Liz Tuddenham on Fri Sep 20 10:21:52 2024
    Liz Tuddenham <liz@poppyrecords.invalid.invalid> wrote:

    [...]
    Something like this:
    http://www.poppyrecords.co.uk/other/Connector.gif

    or this, for a stronger retaining force?

    http://www.poppyrecords.co.uk/other/Connector2.gif


    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Liz Tuddenham on Fri Sep 20 04:33:45 2024
    On 9/20/2024 1:57 AM, Liz Tuddenham wrote:
    I suspect the adhering "metal" piece has to be on the skin
    of the device as the magnetic field falls off quickly with
    distance -- diluting the ability of the cable to remain
    EXACTLY where desired. A "decal" over the surface likely
    would be tolerable...

    Would a rounded bump on the device be acceptable? A matching hollow in
    the cable end could then locate over it.

    It would depend on how "rounded" the bump was. And, how
    tightly the "insert" matched the "equipment" plane.

    When not "mated", the "bumps" are most often touched
    (think of them as buttons and indicators when not acting
    as communication ports). E.g., the emitter normally
    visibly indicates "status"; "touching" it acts to
    invoke IDENTIFY/TRAP/RESET/POWER/SHUTDOWN functions.
    So, the bump makes it easier to find with a fingertip
    (otherwise, you have to be able to perceive the
    difference between the glass of the jewel and the material
    of the case)

    Oils (and dirt) from hands will want to accumulate on those
    surfaces. Easily wiping them clean has to remove ALL traces
    of that crud (because the person cleaning them may not be
    able to SEE them -- blind/visually impaired -- but, others
    *will* and would notice how grimey it appears)

    [Imagine being blind and someone asks to use your toilet...
    are you ever *sure* that they don't come out totally
    disgusted by what THEY saw that you *haven't*? <ick>]

    Something like this:
    http://www.poppyrecords.co.uk/other/Connector.gif

    That's sort of what I was thinking though I was imagining the
    magnet on the cable end (because there can be many such
    ports in close proximity to each other -- 5/8" apart, hence
    the limit of 1/2" -- but only one cable end).

    I imagined the bump as being the glass piece with the
    *detector and emitter* behind it (internal to the
    "equipment") and an annular ring surrounding/framing
    the glass jewel. The ring magnet would be on the
    cable end with an inner diameter just larger than
    the glass jewel.

    In the case of an attached *dongle*, there would be a
    corresponding detector and emitter in the dongle.
    For a cable, fiber could suffice over short distances
    (else put the electronics on the end of the cable).

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Joe Gwinn@21:1/5 to blockedofcourse@foo.invalid on Fri Sep 20 12:38:03 2024
    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.

    Joe Gwinn




    I have a 1/4" dia glass "jewel" that is just barely convex
    to protect the optical port and support light passage.
    The slight bump helps locate the port as well as some small
    assistance in keeping the mated "cable" positioned properly.

    In no case can the needs of the port exceed a concentric
    diameter of 1/2". I plan for the magnet to only be present
    in the mating cable so its adhesion will be determined by
    the metallic ring surrounding the jewel.

    I figure I need to specify a magnet strong enough to
    "support" (against the force of gravity exerted on the
    mass of the cable) the cable in a horizontal position
    (i.e., "mated to the ceiling"). And, to support the
    cantilevered weight of the cable when mounted
    vertically.

    I may opt to implement the "cable" as a wireless dongle
    if the weight of the cable assembly starts to compromise that
    magnetic adherence.

    I guess I also need to consider the magnetic force exerted
    through the friction between the mating surfaces when
    mounted vertically (so the cable doesn't "slide down the wall")

    Anything else I should consider? I realize that the cable end
    now will have a tendency to want to grab onto metallic objects
    so have to factor that into my dongle vs. cable decision
    (it's a lot easier to control the position of a dongle in
    space than the end of a possibly *dangling* cable!)

    I suspect the adhering "metal" piece has to be on the skin
    of the device as the magnetic field falls off quickly with
    distance -- diluting the ability of the cable to remain
    EXACTLY where desired. A "decal" over the surface likely
    would be tolerable...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Joe Gwinn on Fri Sep 20 12:26:44 2024
    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?

    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".

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Joe Gwinn@21:1/5 to blockedofcourse@foo.invalid on Fri Sep 20 17:07:37 2024
    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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Joe Gwinn on Fri Sep 20 20:07:33 2024
    On 9/20/2024 2:07 PM, Joe Gwinn wrote:
    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.

    This argues AGAINST the use of a "dongle" as that would likely
    find itself stored in pockets and other places where detritus
    could accumulate.

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

    I usually use duct tape to pick up steel filings/shavings.
    The cloth backing seems to "absorb" the bits better.

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

    The environment tends not to include metal bits -- unless
    devices are installed in *metal* Jboxes that may have been
    drilled for mounting.

    Dirt (from hands) is more likely to be the contaminant.
    And, will find its way into the smallest of cracks/seams.
    (consider how tedious it is to clean a mouse, keyboard,
    etc. so that it truly looks "clean enough to seem new")

    I'd thought about disposable/replaceable "double-sticky"
    pads that could be used to adhere the cable end to the
    "equipment". But, that would be tedious when you want
    to connect to multiple devices and have to keep peeling
    old pads off. And, would likely leave adhesive residue
    that would attract MORE than just dirt/oils from hands.

    I'd also thought about semi-adhesive strips to deploy to PULL
    the crud off of these surfaces but that assumes folks are aware
    of how dirty the "look" AND how willing they are to maintain a
    supply of "cleaning strips".

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to Joe Gwinn on Sat Sep 21 08:48:09 2024
    Joe Gwinn <joegwinn@comcast.net> wrote:

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

    If the surface is too convoluted for the tape to work, there is a
    product in the UK called "Copydex", which is sold as a carpet glue but
    can be used to remove debris from a magnet. It is an emulsified latex
    solution which doesn't stick well to metal surfaces and can be peeled
    off easily.

    You apply the Copydex thickly over the surface to be cleaned - and then
    wait. Eventually the milky white liquid dries to complete transparency,
    then it is strong enough to be peeled off, bringing the debris with it.

    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Liz Tuddenham on Sat Sep 21 01:30:50 2024
    On 9/21/2024 12:48 AM, Liz Tuddenham wrote:
    Joe Gwinn <joegwinn@comcast.net> wrote:

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

    If the surface is too convoluted for the tape to work, there is a
    product in the UK called "Copydex", which is sold as a carpet glue but
    can be used to remove debris from a magnet. It is an emulsified latex solution which doesn't stick well to metal surfaces and can be peeled
    off easily.

    You apply the Copydex thickly over the surface to be cleaned - and then
    wait. Eventually the milky white liquid dries to complete transparency,
    then it is strong enough to be peeled off, bringing the debris with it.

    I would imagine any of the "silicone caulks" would work
    equally well.

    The downside with any of these is that there is a
    "drying time". I don't imagine the folks using
    this bit of kit would sit around waiting before
    reusing (or retiring) it. <frown> Imagine having
    to similarly clean a 'scope probe between uses...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to Don Y on Sat Sep 21 10:23:14 2024
    Don Y <blockedofcourse@foo.invalid> wrote:

    On 9/21/2024 12:48 AM, Liz Tuddenham wrote:
    Joe Gwinn <joegwinn@comcast.net> wrote:

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

    If the surface is too convoluted for the tape to work, there is a
    product in the UK called "Copydex", which is sold as a carpet glue but
    can be used to remove debris from a magnet. It is an emulsified latex solution which doesn't stick well to metal surfaces and can be peeled
    off easily.

    You apply the Copydex thickly over the surface to be cleaned - and then wait. Eventually the milky white liquid dries to complete transparency, then it is strong enough to be peeled off, bringing the debris with it.

    I would imagine any of the "silicone caulks" would work
    equally well.

    It needs to peel off easily. The silicone caulk I have used has always
    stuck very firmly to metal.


    The downside with any of these is that there is a
    "drying time". I don't imagine the folks using
    this bit of kit would sit around waiting before
    reusing (or retiring) it. <frown> Imagine having
    to similarly clean a 'scope probe between uses...

    Yes, this is very much a specialist tool for getting metal debris out of
    magnet gaps in moving coil meter movements or disc cutterheads, where
    time is not a major factor.

    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Liz Tuddenham on Sat Sep 21 02:50:53 2024
    On 9/21/2024 2:23 AM, Liz Tuddenham wrote:
    I would imagine any of the "silicone caulks" would work
    equally well.

    It needs to peel off easily. The silicone caulk I have used has always
    stuck very firmly to metal.

    I think if you were dealing with something "fine" you
    would have a problem. But, if you can firmly grasp the
    one piece and peal back the caulk, it doesn't seem to be
    a problem.

    I often use this to make molds from "positive" articles
    instead of a more solid-setting material (e.g., plaster or wax).

    The downside with any of these is that there is a
    "drying time". I don't imagine the folks using
    this bit of kit would sit around waiting before
    reusing (or retiring) it. <frown> Imagine having
    to similarly clean a 'scope probe between uses...

    Yes, this is very much a specialist tool for getting metal debris out of magnet gaps in moving coil meter movements or disc cutterheads, where
    time is not a major factor.

    Different use pattern. The communication cable is used
    most like a 'scope probe -- attach to one access point,
    examine/interact data stream, detach and move to the next.

    I use it for diagnostics, debugging and installing "secrets".
    As it is not uncommon for folks (nowadays) to exploit
    "internal/secret" access ports (e.g., "to start a shell on
    tty0..."), having something other than a 4 pin header to which
    you can attach a TTL-level serial device raises the bar a bit.
    (having all of the comms over that port encrypted makes it
    virtually unattainable!) And, of course, not having to
    perforate the case to provide access to same is a win as well!

    None of these are activities where the user would have an
    abundance of patience...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Joe Gwinn@21:1/5 to Liz Tuddenham on Sat Sep 21 11:54:52 2024
    On Sat, 21 Sep 2024 08:48:09 +0100, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    Joe Gwinn <joegwinn@comcast.net> wrote:

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

    If the surface is too convoluted for the tape to work, there is a
    product in the UK called "Copydex", which is sold as a carpet glue but
    can be used to remove debris from a magnet. It is an emulsified latex >solution which doesn't stick well to metal surfaces and can be peeled
    off easily.

    You apply the Copydex thickly over the surface to be cleaned - and then
    wait. Eventually the milky white liquid dries to complete transparency,
    then it is strong enough to be peeled off, bringing the debris with it.

    Sounds like a modern equivalent to soft Collodion, which is widely
    used to clean optical surfaces.

    .<https://en.wikipedia.org/wiki/Collodion>


    Joe Gwinn

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)