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1 hour ago, StringJunky said:

 Yep, they are very strong. I bought one for magnetic fishing. When attracted to something they slam HARD!

There are easier ways to catch fish.  It takes 16 Teslas to levitate a frog, so you'd need at least that, and several megawatts to power the magnet,  for the average fish.  

😁

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2 hours ago, TheVat said:

There are easier ways to catch fish.  It takes 16 Teslas to levitate a frog, so you'd need at least that, and several megawatts to power the magnet,  for the average fish.  

😁

LOL! It's interesting how much low value coinage gets thrown into lakes. I suppose people are seeing how many skips they can get a coin to do across the surface.

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22 hours ago, StringJunky said:

LOL! It's interesting how much low value coinage gets thrown into lakes. I suppose people are seeing how many skips they can get a coin to do across the surface.

In America, the preference is throwing people into lakes more than coins.  

Really, hadn't given much thought to how coinage gets into lakes but that could be one  way.  Does magnetic fishing just retrieve coins with nickel or iron in the mix?

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27 minutes ago, TheVat said:

In America, the preference is throwing people into lakes more than coins.  

Really, hadn't given much thought to how coinage gets into lakes but that could be one  way.  Does magnetic fishing just retrieve coins with nickel or iron in the mix?

US coins, other than steel pennies from WWII, aren't magnetic. So magnet fishing isn't using the right bait for those coins.

(even nickels aren't magnetic. Ni-Cu alloys require at least 56% Ni to show ferromagnetism at normal temperatures, and the coin is 25%

https://journals.aps.org/pr/abstract/10.1103/PhysRev.38.828 )

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I just pulled out my non-US coins (many gathered from geocaching) and a surprising number are magnetic, including the Canadian twonie , quarter and nickel, Italian 500 L(bimetal, like the twonie), Iceland 1Kr and 5Kr, 1 Yuan (China?), French 1/2 and 1 Franc, Ecuador 5 cent, Netherlands 1 Guilder, and a few more not easily identifiable (but a few are probably Russian rubles)

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21 hours ago, TheVat said:

In America, the preference is throwing people into lakes more than coins.  

Really, hadn't given much thought to how coinage gets into lakes but that could be one  way.  Does magnetic fishing just retrieve coins with nickel or iron in the mix?

Some are, some aren't. I suppose the alloy mix changes periodically with new editions. The bimetallic ones are fairly weakly attracted. Generally, the coppers that attract are very hard to pull off. It WhatsAppImage2024-06-12at12_35.52_309a924a.thumb.jpg.4dd65aedb147339da90e6921588f56c7.jpgWhatsAppImage2024-06-12at12_36.27_c0f5cc92.thumb.jpg.541efe9e6f410b160b75e59e391acd63.jpg

It might be a security feature by the Royal Mint to mix up each yearly edition in terms of magnetism to combat counterfeits. I doubt the bimetallics could be pulled in from a water as it's too weak. There may be magnetic 50p's, but not in my change

Edited by StringJunky
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  • 3 weeks later...
Posted (edited)

Hi @Prajna

I was intrigued by this thread. I appreciate your earnesty and I think it’s a cool looking project. I don't believe it will generate any free energy though, but the discussion is interesting to me anyway.

The discussion around "is work done by a magnetic field" was quite difficult to follow in my opinion.

I thought maybe I could help with explaining in layman’s terms where I believe the error in your thinking is.

It seems that basically you think that the magnetic field is something that we somehow can steal energy from to move stuff. Let's see why this isn't a good way of looking at things.

You know that you can “slingshot” satellites around planets, using the planet’s gravitational field, and the satellite gets faster, leaves the planet even faster than it went in. It gained kinetic energy. Where did this kinetic energy come from? It doesn’t “magic it” from the gravitational field, as if the field were an ether-like-thing that you can harvest energy from. The satellite steals kinetic energy from from the planet, which slows down by a teeny amount. The field only moderated the interaction, like a string. So there isn’t energy we can somehow steal forever from the gravitational field, we stole it from Earth.

Just like if I have the kids toy, a rubber ball connected to a wooden bat by elastic. When you have it going, it looks effortless, the ball is zipping to and fro with hardly no perceptible movement from me. But we know, when the ball is flying away from the bat, it requires energy from me to pull/resist slightly, then I have to push/hit the ball slightly. The energy of the system doesn’t come from the elastic or the rubber-ness of the ball. It comes from me. If I stop my very small wrist/bat movements the system loses energy. Imagine the same toy but the bat is super tiny, the same weight as the ball, now I have to really move my arm hit the ball harder. it becomes more obvious that I am the one putting all the energy into the system.

The reason I use these silly examples, is because it shows that when you have a system where one thing is big (me and the bat, or a planet) and the other is small (ball / satellite), and it can look like you are getting a lot of energy / force from the field of attraction - the gravity field, or the elastic.

You gave the intelligent common sense example of what if you push something ferrous along a table, near to a magnet above the table, at some point the magnet will suck it upwards. Why is the work not coming from the magnetic field? Because it’s the various mechanical forces that are needed to do the lifting.

Let’s say the magnet is held above the table by a thin string from the ceiling. What will we see in super slo-mo? We will see the magnet pulled downward very slightly toward the table/object, the string will extend, this puts a tension in the string, a force which acts upward. So, whatever the magnetic attraction, when we consider the whole system, the lifting still requires this upward tension force. The magnetic attraction in this case is just the linkage, like a sort of elastic but in reverse. The key point is we didn’t need to use energy “from the magnetic field”, to do the lift, but it was all correctly supplied and accounted for from the upward pulling tension.

So we can see there is always some force, some mechanical situation, which sometimes isn’t obvious, maybe cos we’re not thinking about  the whole system. So, similarly in your machine, the magnets and fields are just distributing or transferring the forces from the movements of the machine, just like mechanical linkages. This is always what magnets do, just that is seems more mysterious when we play with magnets because they’re unfamiliar - it seems to us like “I don’t apply any force or do anything, but the metal pieces move… ”

Imagine your machine, but the rotor, instead of having teeth between magnets, had smooth waves of fat and thin sections, between 2 rollers, which are now mechanically oscillated together and apart, just like the magnets were. This is basically the situation, it’s some kind of drive to convert rotary to reciprocating movement, then another thing to convert the reciprocating movement back to rotary. What makes you think that doing part of it with magnets can make the whole machine to go over 100% efficiency ? The magnets will push, pull, on mechanical parts,  induce pushing and pulling, and maybe lose energy in currents or heat. Where is it gaining the energy from ?

Anyway it’s a cool project, it made me think,  and I hope you get to complete a build of it. Please post results.

 

to everyone else, it's my first post so, sorry if I said anything stupid.

Edited by alebrije0871
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4 hours ago, alebrije0871 said:

Hi @Prajna

I was intrigued by this thread. I appreciate your earnesty and I think it’s a cool looking project. I don't believe it will generate any free energy though, but the discussion is interesting to me anyway.

....

Anyway it’s a cool project, it made me think,  and I hope you get to complete a build of it. Please post results.

to everyone else, it's my first post so, sorry if I said anything stupid.

Hey, thanks for the response and your clear examples. In my view it boils down to a simple question: is the eddy current drag in the metal fingers more than, less than or equal to the energy captured by switching the magnetic flux? I had rather hoped, in posting here, that someone might be able to calculate (or even have an intuitive sense of, what that eddy current drag might be and how it might compare to the forces induced in the Bellcrank by the opposed magnets. There will, of course, be other losses in the system but I am interested to know the answer to the drag Vs magnetic forces in this system. It's all very well illustrating the principles with examples but here we have a simple example that could be analysed and the results would be an explanation on their own.

In any case, I have one more day of 3D printing to do and some water jet cutting to arrange and I will be able to assemble and test the device. For the present the rotor is only a first best guess - I may need to change the size of the fingers or thickness to contain enough of the field to switch the flux sufficiently, but we shall see.

Thanks again.

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51 minutes ago, Prajna said:

Hey, thanks for the response and your clear examples. In my view it boils down to a simple question: is the eddy current drag in the metal fingers more than, less than or equal to the energy captured by switching the magnetic flux? I had rather hoped, in posting here, that someone might be able to calculate (or even have an intuitive sense of, what that eddy current drag might be and how it might compare to the forces induced in the Bellcrank by the opposed magnets. There will, of course, be other losses in the system but I am interested to know the answer to the drag Vs magnetic forces in this system. It's all very well illustrating the principles with examples but here we have a simple example that could be analysed and the results would be an explanation on their own.

In any case, I have one more day of 3D printing to do and some water jet cutting to arrange and I will be able to assemble and test the device. For the present the rotor is only a first best guess - I may need to change the size of the fingers or thickness to contain enough of the field to switch the flux sufficiently, but we shall see.

Thanks again.

 

OK good luck with your testing. I just wanted to say, please don't feel that the lack of response on your question, here is due to ill-will, or no-one knowing any physics. You say it's a "simple example", but it's really not simple simple. For example, I did undergrad physics, and to estimate the forces as you request in your system, is way more complex than any problem I ever saw in labs or exams, or lectures. It's not that it's particularly weird physics, just that there are lots and lots of variables, it's a very "dirty" real life problem.... I can imagine taking it to the total brainbox in my year, and he would spend a couple of full evenings working on it, and eventually be like, "I kind of got an answer, but, only for a rotor which is infinitely thin, and if the magnets don't move at all. Oh, and only if the speed of rotor is so slow that you can avoid the blahblah 2nd order effect." So it's kind of a big ask. Of course I could be wrong, perhaps there is someone here who did their phd on rotors spinning in magnets.

The other thing is, you did get a very good intuitive answer already in this thread -- someone already said the energy lost thru drag etc must be more than the energy generated, but you don't seem to accept it. I'm 100% sure that the physicists on this thread are all intuitively sure that energy lost thru drag etc is more than what you gain, because otherwise, you would be gaining energy from nowhere. I get that you seem to not really be on board with conservation of energy, but for a physicist , it's generally our best way of quickly working out complex problems, of intuiting.  We are taught to look at the energy of a system to see how it will behave.

i think it's super cool to have discussions like this, i just wanted to say in case you feel frustrated that no-one is giving you the answers you want, and at least you see the logic from this side of why not. (answer already seems very obvious due to physics conservation of energy, and the alternative calculation asked for is not easy)

On another note , I am super surprised you didn't do more testing already, like for example just getting a couple of strong magnets from a household store and spinning a  circular saw or lawnmower blade (etc) thru them, just to see how it all felt. I think that is the first thing i would have done, start spinning random things, I guess I am more of an engineer / hacker at heart lol

 

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Posted (edited)

The different drag components isn't strictly mechanical either. You will likely see a drag/drift effect associated with similarities to a magnetic cyclotron. In so far as the related mathematics most are already mentioned. 

Though we didn't go quite that far via Maxwell. 

The two primary formulas to describe the above will be Lorentz force law and the Magnetic force law. (When you start varying the E and B field you get some interesting side effects)

Edited by Mordred
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17 hours ago, alebrije0871 said:

 

OK good luck with your testing. I just wanted to say, please don't feel that the lack of response on your question, here is due to ill-will, or no-one knowing any physics. You say it's a "simple example", but it's really not simple simple. For example, I did undergrad physics, and to estimate the forces as you request in your system, is way more complex than any problem I ever saw in labs or exams, or lectures. It's not that it's particularly weird physics, just that there are lots and lots of variables, it's a very "dirty" real life problem.... I can imagine taking it to the total brainbox in my year, and he would spend a couple of full evenings working on it, and eventually be like, "I kind of got an answer, but, only for a rotor which is infinitely thin, and if the magnets don't move at all. Oh, and only if the speed of rotor is so slow that you can avoid the blahblah 2nd order effect." So it's kind of a big ask. Of course I could be wrong, perhaps there is someone here who did their phd on rotors spinning in magnets.

The other thing is, you did get a very good intuitive answer already in this thread -- someone already said the energy lost thru drag etc must be more than the energy generated, but you don't seem to accept it. I'm 100% sure that the physicists on this thread are all intuitively sure that energy lost thru drag etc is more than what you gain, because otherwise, you would be gaining energy from nowhere. I get that you seem to not really be on board with conservation of energy, but for a physicist , it's generally our best way of quickly working out complex problems, of intuiting.  We are taught to look at the energy of a system to see how it will behave.

i think it's super cool to have discussions like this, i just wanted to say in case you feel frustrated that no-one is giving you the answers you want, and at least you see the logic from this side of why not. (answer already seems very obvious due to physics conservation of energy, and the alternative calculation asked for is not easy)

On another note , I am super surprised you didn't do more testing already, like for example just getting a couple of strong magnets from a household store and spinning a  circular saw or lawnmower blade (etc) thru them, just to see how it all felt. I think that is the first thing i would have done, start spinning random things, I guess I am more of an engineer / hacker at heart lol

 

Ah, well I was not so much wanting an answer as hoping for one. I would have thought that a rough answer could be approached by working with the strength of the magnets - N58 10mm x 3mm - and choosing an arbitrary thickness of the fingers, say 1mm, assume the area of the finger in the gap is the same as the area of the magnets, the gap varies between a couple of mm (just so it doesn't reach the finger) and 40mm. But maybe it is much more complicated than that, even for a rough estimate. Sure, there is the overriding law of thermodynamics, dogma++, as it were, that says that one way or other the forces must be balanced but science is about heresy and challenging dogma. In fact, that about sums science up: it is the recorded history of stuff we were certain of but was then successfully challenged and overturned. When we treat science as religion and refuse to even test things because dogma then we get stuck. I realise that scientific laws are even more sacrosanct dogma than theories and hypotheses but there is a small possibility that energy enters the system by some as yet unidentified means and I am not convinced that we have yet fully understood magnetism. Who was it, a member of the Royal Society, who said, back in the 1800s, that we understood all of physics and there were only a few minor details to nail down?

I have done a few rough and ready experiments with magnets and sheets of iron, which is where my (perhaps naive) optimism comes from. It seemed to me, and to someone on an engineering forum who did his own experiments, that interjecting a sheet of steel in the magnetic field 1. collapsed the repulsive field causing the magnets to be attracted towards the sheet and, 2. didn't feel to have much in the way of eddy current drag.

Maybe physicists understand magnetism at the level of electrons but I'm not convinced many of them have actually picked up and played with them. For all that the field is supposed to be well studied I recently watched a video with Joe May, the inventor of the Joe Cell, who demonstrated some astounding effects with a ring magnet that had been broken apart. Perhaps there is more to know and perhaps there is a way to use the magnetic field as something more than a spring. Because I have no other means, short of some serious study of physics, for me to evaluate the forces in this system I will just carry on developing this prototype and test it. Anyway, empirical evidence is the most convincing.

It may (certainly will, according to most of the assessments I have seen) turn out that this is but a very good example to show how 'free energy' is impossible and the laws of thermodynamics are as certain as the law of karma, or perhaps this device will produce more output than what we input by way of the rotor and still not break the laws of thermodynamics (because we might identify where the extra power is coming from). In any case I will end up with an interesting device even if it is just a curiosity.

Thanks for your interest and I will certainly keep the forum updated with my results.

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The parts are all printed. I just have the rotor to make. I was going to get my previous design water jet cut but I have redesigned it so that it is easy for me to make with the tools I have.parts.thumb.jpg.520cfbd486fad2bb03b194c2223ab5d4.jpg

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Well, the SFT-Mk5 is all assembled but sadly it is not rigid enough. I'm hoping that if I beef up the supports for the bellcranks that might make it stiff enough to work. The problem at the moment is that the magnets stick to the rotor and the mechanism is supposed to limit their travel so that can't happen but there is too much movement in the bellcrank mounts and that lets the magnets get too close to the rotor. Oh well, iterative process.

 

SMT-Mk5 Assy.png

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