OT -- magnetic bearings

[Snidely]

A video I recently watched was about the development of vertical
windmill generators, primarily for household/farm power provisioning,
supplmental, off-grid, and backup supplies.

One of the construction details is the use of magnetic bearings on the
main vertical shaft, which supports the vanes, which are visually
similar to oil drum halves. In describing these, the developer
mentioned that the manufacturer of the magnets promised that they could
run 42 years with no significant degradation.

My question is whether this longevity is due to each of the magnets
acting a keeper for the other. I know that for traditional horseshoe
magnets it is recommended to use a keeper bar across the ends to aid in
retaining the magnetization. Is something similar going on when two
ring magnets are stacked? I don't know what the shape of the magnetic
field is in ring magnets, and I don't have a supply of fine iron
filings, although I do have some thumbprint-sized disk magnets I ccould
put under the paper.

Magnetic bearings at:

For those interested in the turbine design, there's discussion of vane
shape at
http://youtu.be/AyF0td7oygM

/dps

[Bebercito]

Post by Snidely
A video I recently watched was about the development of vertical
windmill generators, primarily for household/farm power provisioning,
supplmental, off-grid, and backup supplies.
One of the construction details is the use of magnetic bearings on the
main vertical shaft, which supports the vanes, which are visually
similar to oil drum halves. In describing these, the developer
mentioned that the manufacturer of the magnets promised that they could
run 42 years with no significant degradation.
My question is whether this longevity is due to each of the magnets
acting a keeper for the other. I know that for traditional horseshoe
magnets it is recommended to use a keeper bar across the ends to aid in
retaining the magnetization. Is something similar going on when two
ring magnets are stacked? I don't know what the shape of the magnetic
field is in ring magnets, and I don't have a supply of fine iron
filings, although I do have some thumbprint-sized disk magnets I ccould
put under the paper.

ChatGPT's take on this:

---
The longevity of the magnets used in magnetic bearings for vertical
windmill generators does indeed relate to the design and arrangement of
the magnets, among other factors. Using magnetic bearings can
significantly reduce friction and wear compared to traditional
mechanical bearings, which enhances the lifespan of the system.

1. Magnet Degradation and Longevity:
The claim of 42 years without significant degradation is primarily based
on the stability of the materials used in the magnets (often neodymium
or samarium-cobalt) and their resistance to demagnetization. Factors
such as temperature, humidity, and external magnetic fields can affect
magnet performance, so proper design and environmental considerations
play a key role in achieving long life.

2. Magnetic Keepers:
Indeed, magnetic keepers are used in traditional horseshoe magnets to
help retain magnetization by providing a closed magnetic circuit. This
helps to minimize the loss of magnetic flux. In a similar way, stacking
ring magnets can maintain a strong magnetic field, but unlike horseshoe
magnets, the geometry and configuration play an important role.

When you stack two ring magnets, they do create a more unified magnetic
field, but they don't necessarily act as keepers in the way traditional
magnets do. Instead, they work together to form a stronger overall
magnetic field while helping to equalize the magnetic forces at play.
The design of the magnetic circuit in the bearing assembly may also
incorporate other factors, such as pole arrangements and air gaps, which
can optimize performance.

3. Magnetic Field Characteristics:
The shape of the magnetic field in a ring magnet is not as
straightforward as in horseshoe magnets. In general, a ring magnet has a
magnetic field that flows from one side of the magnet through the center
hole and back around to the other side. The field lines are concentrated
near the edges, and there is a significant field within the ring as
well.

Using fine iron filings or similar materials can help visualize this
field. The filings will tend to align along the magnetic field lines,
giving you a good indication of the field strength and direction.

4. Conclusion:
In conclusion, the longevity of the magnets in your video is likely due
to a combination of the high-quality materials used, the arrangement of
the magnets, and the specific design of the magnetic bearing system that
minimizes detrimental influences. While stacking magnets doesn't provide
the same function as traditional keepers, it can help optimize the
magnetic circuit in certain configurations.

If you're interested in further exploring the behavior of magnets,
experimenting with your disk magnets under a sheet of paper with iron
filings can indeed provide insight into how magnetic fields work!
---

Post by Snidely
http://youtu.be/AyF0td7oygM
For those interested in the turbine design, there's discussion of vane
shape at
http://youtu.be/AyF0td7oygM
/dps

[Snidely]

Post by Bebercito

Post by Snidely
A video I recently watched was about the development of vertical
windmill generators, primarily for household/farm power provisioning,
supplmental, off-grid, and backup supplies.
One of the construction details is the use of magnetic bearings on the
main vertical shaft, which supports the vanes, which are visually
similar to oil drum halves. In describing these, the developer
mentioned that the manufacturer of the magnets promised that they could
run 42 years with no significant degradation.
My question is whether this longevity is due to each of the magnets
acting a keeper for the other. I know that for traditional horseshoe
magnets it is recommended to use a keeper bar across the ends to aid in
retaining the magnetization. Is something similar going on when two
ring magnets are stacked? I don't know what the shape of the magnetic
field is in ring magnets, and I don't have a supply of fine iron
filings, although I do have some thumbprint-sized disk magnets I ccould
put under the paper.

---
The longevity of the magnets used in magnetic bearings for vertical
windmill generators does indeed relate to the design and arrangement of
the magnets, among other factors. Using magnetic bearings can
significantly reduce friction and wear compared to traditional
mechanical bearings, which enhances the lifespan of the system.
The claim of 42 years without significant degradation is primarily based
on the stability of the materials used in the magnets (often neodymium
or samarium-cobalt) and their resistance to demagnetization. Factors
such as temperature, humidity, and external magnetic fields can affect
magnet performance, so proper design and environmental considerations
play a key role in achieving long life.
Indeed, magnetic keepers are used in traditional horseshoe magnets to
help retain magnetization by providing a closed magnetic circuit. This
helps to minimize the loss of magnetic flux. In a similar way, stacking
ring magnets can maintain a strong magnetic field, but unlike horseshoe
magnets, the geometry and configuration play an important role.
When you stack two ring magnets, they do create a more unified magnetic
field, but they don't necessarily act as keepers in the way traditional
magnets do. Instead, they work together to form a stronger overall
magnetic field while helping to equalize the magnetic forces at play.
The design of the magnetic circuit in the bearing assembly may also
incorporate other factors, such as pole arrangements and air gaps, which
can optimize performance.
The shape of the magnetic field in a ring magnet is not as
straightforward as in horseshoe magnets. In general, a ring magnet has a
magnetic field that flows from one side of the magnet through the center
hole and back around to the other side. The field lines are concentrated
near the edges, and there is a significant field within the ring as
well.
Using fine iron filings or similar materials can help visualize this
field. The filings will tend to align along the magnetic field lines,
giving you a good indication of the field strength and direction.
In conclusion, the longevity of the magnets in your video is likely due
to a combination of the high-quality materials used, the arrangement of
the magnets, and the specific design of the magnetic bearing system that
minimizes detrimental influences. While stacking magnets doesn't provide
the same function as traditional keepers, it can help optimize the
magnetic circuit in certain configurations.
If you're interested in further exploring the behavior of magnets,
experimenting with your disk magnets under a sheet of paper with iron
filings can indeed provide insight into how magnetic fields work!
---

Post by Snidely
http://youtu.be/AyF0td7oygM
For those interested in the turbine design, there's discussion of vane
shape at
http://youtu.be/AyF0td7oygM
/dps

Well, that seems like it might be a useful answer.

/dps

[Joy Beeson]

Post by Snidely
I don't have a supply of fine iron
filings,

The oxygen absorber packets in my pill bottles stick to a magnet. I
haven't opened one because it would make a mess.

[jerryfriedman]

Post by Joy Beeson

Post by Snidely
I don't have a supply of fine iron
filings,

The oxygen absorber packets in my pill bottles stick to a magnet. I
haven't opened one because it would make a mess.

You could clean it up with a magnet, though.

--
Jerry Friedman

--

[Bertel Lund Hansen]

Post by jerryfriedman

Post by Joy Beeson
The oxygen absorber packets in my pill bottles stick to a magnet. I
haven't opened one because it would make a mess.

You could clean it up with a magnet, though.

Sure, but getting it off the magnet is quite a job. And if you use one
of the modern extremely strong magnets, it's hopeless.

[Joy Beeson]

On Thu, 7 Nov 2024 07:07:27 +0100, Bertel Lund Hansen

Post by Bertel Lund Hansen

Post by jerryfriedman

Post by Joy Beeson
The oxygen absorber packets in my pill bottles stick to a magnet. I
haven't opened one because it would make a mess.

You could clean it up with a magnet, though.

Sure, but getting it off the magnet is quite a job. And if you use one
of the modern extremely strong magnets, it's hopeless.

One could cover the magnet with a piece of thin, tightly-woven cloth.

[Bertel Lund Hansen]

Post by Joy Beeson

Post by Bertel Lund Hansen

Post by jerryfriedman
You could clean it up with a magnet, though.

Sure, but getting it off the magnet is quite a job. And if you use one
of the modern extremely strong magnets, it's hopeless.

One could cover the magnet with a piece of thin, tightly-woven cloth.

Good idea. I never thought of that.

[Mark Brader]

Post by Bertel Lund Hansen

Post by Joy Beeson

Post by Bertel Lund Hansen
Sure, but getting it off the magnet is quite a job. And if you use one
of the modern extremely strong magnets, it's hopeless.

One could cover the magnet with a piece of thin, tightly-woven cloth.

Good idea. I never thought of that.

Neither did I -- plastic film, not being porous, is the obvious cboice.

[J. J. Lodder]

Snidely <***@gmail.com> wrote:
[sorry about being late, been busy with other things]

Post by Snidely
A video I recently watched was about the development of vertical
windmill generators, primarily for household/farm power provisioning,
supplmental, off-grid, and backup supplies.
One of the construction details is the use of magnetic bearings on the
main vertical shaft, which supports the vanes, which are visually
similar to oil drum halves. In describing these, the developer
mentioned that the manufacturer of the magnets promised that they could
run 42 years with no significant degradation.
My question is whether this longevity is due to each of the magnets
acting a keeper for the other. I know that for traditional horseshoe
magnets it is recommended to use a keeper bar across the ends to aid in
retaining the magnetization. Is something similar going on when two
ring magnets are stacked? I don't know what the shape of the magnetic
field is in ring magnets, and I don't have a supply of fine iron
filings, although I do have some thumbprint-sized disk magnets I ccould
put under the paper.

Eh, no. Your thinking on this is fundamentally misguided.
A keeper bar, or better yet, a horseshoe with the opposite polarity,
helps against demagnisation by keeping the field lines inside the iron.
(putting it picturally)
A (repelling) horseshoe forced against it does just the opposite.
It creates a neutral plane without penetrating field lines between the
magnets, and forces the field lines out, away from the poles.
This will tend to demagnetise.

In magnetic bearings the magnets are always used in a repulsive mode.
The idea is to avoid friction by keeping surfaces apart.
The magnets surviving nevertheless is entirely due
to the use of new superior materials.
It wouldn't work very well with oldfashioned steel.

Jan
(is this sufficiently clear, or should I try for ASCII art?)

[Snidely]

Post by J. J. Lodder
[sorry about being late, been busy with other things]

Post by Snidely
A video I recently watched was about the development of vertical
windmill generators, primarily for household/farm power provisioning,
supplmental, off-grid, and backup supplies.
One of the construction details is the use of magnetic bearings on the
main vertical shaft, which supports the vanes, which are visually
similar to oil drum halves. In describing these, the developer
mentioned that the manufacturer of the magnets promised that they could
run 42 years with no significant degradation.
My question is whether this longevity is due to each of the magnets
acting a keeper for the other. I know that for traditional horseshoe
magnets it is recommended to use a keeper bar across the ends to aid in
retaining the magnetization. Is something similar going on when two
ring magnets are stacked? I don't know what the shape of the magnetic
field is in ring magnets, and I don't have a supply of fine iron
filings, although I do have some thumbprint-sized disk magnets I ccould
put under the paper.

Eh, no. Your thinking on this is fundamentally misguided.
A keeper bar, or better yet, a horseshoe with the opposite polarity,
helps against demagnisation by keeping the field lines inside the iron.
(putting it picturally)
A (repelling) horseshoe forced against it does just the opposite.
It creates a neutral plane without penetrating field lines between the
magnets, and forces the field lines out, away from the poles.
This will tend to demagnetise.
In magnetic bearings the magnets are always used in a repulsive mode.
The idea is to avoid friction by keeping surfaces apart.
The magnets surviving nevertheless is entirely due
to the use of new superior materials.
It wouldn't work very well with oldfashioned steel.
Jan
(is this sufficiently clear, or should I try for ASCII art?)

Thank you! I was hoping you'd chime in. I think I got it.

/dps

[J. J. Lodder]

Post by Snidely

Post by J. J. Lodder
[sorry about being late, been busy with other things]

Post by Snidely
A video I recently watched was about the development of vertical
windmill generators, primarily for household/farm power provisioning,
supplmental, off-grid, and backup supplies.
One of the construction details is the use of magnetic bearings on the
main vertical shaft, which supports the vanes, which are visually
similar to oil drum halves. In describing these, the developer
mentioned that the manufacturer of the magnets promised that they could
run 42 years with no significant degradation.
My question is whether this longevity is due to each of the magnets
acting a keeper for the other. I know that for traditional horseshoe
magnets it is recommended to use a keeper bar across the ends to aid in
retaining the magnetization. Is something similar going on when two
ring magnets are stacked? I don't know what the shape of the magnetic
field is in ring magnets, and I don't have a supply of fine iron
filings, although I do have some thumbprint-sized disk magnets I ccould
put under the paper.

Eh, no. Your thinking on this is fundamentally misguided.
A keeper bar, or better yet, a horseshoe with the opposite polarity,
helps against demagnisation by keeping the field lines inside the iron.
(putting it picturally)
A (repelling) horseshoe forced against it does just the opposite.
It creates a neutral plane without penetrating field lines between the
magnets, and forces the field lines out, away from the poles.
This will tend to demagnetise.
In magnetic bearings the magnets are always used in a repulsive mode.
The idea is to avoid friction by keeping surfaces apart.
The magnets surviving nevertheless is entirely due
to the use of new superior materials.
It wouldn't work very well with oldfashioned steel.
Jan
(is this sufficiently clear, or should I try for ASCII art?)

Thank you! I was hoping you'd chime in. I think I got it.

As you may know MacSoup is an off-line newsclient.
(perhaps one of the last still used)
This has the consequence that replying directly is impossible.
I don't have to practise 'sitting on my hands',
as discussed otherthread.

A consequence is that I have a huge pile
of 'to be answered' (perhaps, if ever) postings.
Most never make it, a few, like yours,
get recovered and make it to the outside world.

But if I am not mistaken you are one of the other posters here
who may reply with long delays,

Jan

PS Apart from all that, a Darrieus windmill is a really bad idea,
very special circumstances excepted. (perhaps)
Magnetic bearings don't really change that.

[occam]

Post by J. J. Lodder
PS Apart from all that, a Darrieus windmill is a really bad idea,
very special circumstances excepted. (perhaps)
Magnetic bearings don't really change that.

Most people seem to agree about Darrieus windmills.

However looking at the various other options of wind powered generators,
I came across a 'vortex (bladeless) turbine' which vibrates but has no
bearings or other moving parts. Apart from its obscene looks (it looks
like a vibrating dildo in the open air) the idea looks clever and
relatively inexpensive.

Example here:
https://www.bridgestone.com/bwsc/stories/article/2019/11/13-2.html

[J. J. Lodder]

Post by occam

Post by J. J. Lodder
PS Apart from all that, a Darrieus windmill is a really bad idea,
very special circumstances excepted. (perhaps)
Magnetic bearings don't really change that.

Most people seem to agree about Darrieus windmills.
However looking at the various other options of wind powered generators,
I came across a 'vortex (bladeless) turbine' which vibrates but has no
bearings or other moving parts. Apart from its obscene looks (it looks
like a vibrating dildo in the open air) the idea looks clever and
relatively inexpensive.

Anything vibrating usually is no good, in the longer run.
It breaks by metal fatigue.
Typical example: aircraft engines didn't become safe
until they got rid of those pistons.

Post by occam
https://www.bridgestone.com/bwsc/stories/article/2019/11/13-2.html

And the things also generate very little power.
(relatively)
Not surprising, the area of wind that they can grab is small,

Jan

[Snidely]

Post by J. J. Lodder
Jan
PS Apart from all that, a Darrieus windmill is a really bad idea,
very special circumstances excepted. (perhaps)
Magnetic bearings don't really change that.

I think this is intended for situations where a tower isn't possible, e
and maybe for portable or backup use (noted that solar cells are still
better at this point). It would not be intended for wind farm use.

Speaking of wind farms, when going through Banning Pass (the nearest
wind farm area to me, and on a route I use) I make some effort to
figure if there is a pattern to which turbines are on and which are off
(feathered and/or braked). No wondrous insight so far.

/dps

[J. J. Lodder]

Post by Snidely

Post by J. J. Lodder
Jan
PS Apart from all that, a Darrieus windmill is a really bad idea,
very special circumstances excepted. (perhaps)
Magnetic bearings don't really change that.

I think this is intended for situations where a tower isn't possible, e
and maybe for portable or backup use (noted that solar cells are still
better at this point). It would not be intended for wind farm use.

Well, 'intended'?
It seem more like a solution in desperate search for a problem to me.
In these parts every now and then some misguided architect invents
'an energy building' or something like that,
supposed to be self-sufficient.
So flat roof with solar panels and Darrieus rotors.
This is bad on all counts: it isn't really self-sufficient,
the windflow on the top is turbulent and not strong enough,
and the noise from the rotors keeps the inhabitants awake.
(so once paid for they can be removed)

Post by Snidely
Speaking of wind farms, when going through Banning Pass (the nearest
wind farm area to me, and on a route I use) I make some effort to
figure if there is a pattern to which turbines are on and which are off
(feathered and/or braked). No wondrous insight so far.

Not likely to result. Maintenance will be based on a service contract
that specifies something like 95% availability.
So one in twenty will be stopped, and Poisson will rule.

You might look for the one second synchronous flashers on top.
They really should be accurately synchronous,
because each has its own GPS receiver for timing, [1]

Jan

[1] Pilots say that it is a great sight at night, from above.

[Snidely]

Post by J. J. Lodder
A keeper bar, or better yet, a horseshoe with the opposite polarity,
helps against demagnisation by keeping the field lines inside the iron.
(putting it picturally)

So then I'm being good when I store my worklights magnet to magnet, and
the new materials keep them small.

/dps

[J. J. Lodder]

Post by Snidely

Post by J. J. Lodder
A keeper bar, or better yet, a horseshoe with the opposite polarity,
helps against demagnisation by keeping the field lines inside the iron.
(putting it picturally)

So then I'm being good when I store my worklights magnet to magnet, and
the new materials keep them small.

Certainly. Ferromagnetism is an example of a phase transition.
(at the Curie temperature)
Spins align with any field that may be present,
and in turn they collectively create the field.

So any magnetic field in line with the field that is already there
is good for stability,

Jan

[Snidely]

Post by J. J. Lodder

Post by Snidely

Post by J. J. Lodder
A keeper bar, or better yet, a horseshoe with the opposite polarity,
helps against demagnisation by keeping the field lines inside the iron.
(putting it picturally)

So then I'm being good when I store my worklights magnet to magnet, and
the new materials keep them small.

Certainly. Ferromagnetism is an example of a phase transition.
(at the Curie temperature)
Spins align with any field that may be present,
and in turn they collectively create the field.
So any magnetic field in line with the field that is already there
is good for stability,
Jan

Just the Ising on the cake, eh?

/dps

[J. J. Lodder]

Post by Snidely

Post by J. J. Lodder

Post by Snidely

Post by J. J. Lodder
A keeper bar, or better yet, a horseshoe with the opposite polarity,
helps against demagnisation by keeping the field lines inside the iron.
(putting it picturally)

So then I'm being good when I store my worklights magnet to magnet, and
the new materials keep them small.

Certainly. Ferromagnetism is an example of a phase transition.
(at the Curie temperature)
Spins align with any field that may be present,
and in turn they collectively create the field.
So any magnetic field in line with the field that is already there
is good for stability,
Jan

Just the Ising on the cake, eh?

Don't bother, it's only a model cake,

Jan