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Author Topic: Magnet question  (Read 22301 times)

elecar

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Magnet question
« on: June 02, 2013, 06:09:58 PM »
As you bring 2 opposing magnets together, you need more force to close the gap.
Is there a simple way to determine how much force they require at each point.
I assume if they were 10mm apart to begin with and you moved them closer by 5 mm it would not be a simple case of doubling the force that was required at 10mm, or perhaps it is that simple ?

Low-Q

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Re: Magnet question
« Reply #1 on: June 02, 2013, 06:45:00 PM »
As you bring 2 opposing magnets together, you need more force to close the gap.
Is there a simple way to determine how much force they require at each point.
I assume if they were 10mm apart to begin with and you moved them closer by 5 mm it would not be a simple case of doubling the force that was required at 10mm, or perhaps it is that simple ?
In general it takes greater force to push the magnets together the narrower the distance is. The force is related to the distance between the center of magnetism. Of you have two disc magnets 50mm in diameter and 1mm thick, it takes much more force to bring them together surface to surface, than edge to edge. Even the magnets are the same. The reason is that the center of magnetism is much closer surface to surface (1mm apart), than edge to edge (50mm apart).


The relationship is square to the distance - just like gravity.




Vidar

gyulasun

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Re: Magnet question
« Reply #2 on: June 02, 2013, 07:18:17 PM »
You can use on-line repel force calculators if you search for it.

Here is one at random search: http://www.kjmagnetics.com/calculator.repel.asp

elecar

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Re: Magnet question
« Reply #3 on: June 02, 2013, 07:57:40 PM »
Thank you, that helps a lot, I did try to find  some kind of calculator but was obviously using the wrong terms.

ace569er

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Re: Magnet question
« Reply #4 on: June 02, 2013, 09:16:31 PM »
   I'm still waiting for someone to tell me or even guess. How to counter/calibrate/weaken the push/pull of magnetization/magnetism? It can be done. Also no form of NUMetal is used. There is a arrangement that everyone knows, that simulates a monopole effect. Meaning it uses the north or south magnetization only when arranged this way. Now can some one tell me how to ADD to that array, to counter, calibrate, & weaken the simulated monopole effect? So that the gate/sticky point, is weakened to almost weakness of the driving force, instead of being several times stronger? Clue; you can not cancel it out, only weaken it. Also you do not change the distance, because that will always take more energy to do so then the drive of the arrangement could ever produce. Then if you can guess that, then tell me what last mod is needed to push pass the weakened gate.
    I do want to explain so bad, but it is so simple of a layout. Plus even easier to see why it works when you can see it then do the math for why it does it. That it saddens me no one has even tried to do something, or figure out how one can  counter/calibrate/weaken the gate in itself, without adding any energy at all. Everyone always wants to move something. Needing work to do so. Yet there is a different way to calibrate. First weaken the gate, then use multiple dynamics to overcome it. So I'd like to see some GOOD thought experiments to figure it out. Can anyone guess how? Think simple. Though I guess every arrangement we use today, is so simple yet, took man till recently to figure out...

elecar

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Re: Magnet question
« Reply #5 on: June 02, 2013, 10:42:33 PM »
How do you weaken the gate Ace ?

Low-Q

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Re: Magnet question
« Reply #6 on: June 02, 2013, 10:47:06 PM »
   I'm still waiting for someone to tell me or even guess. How to counter/calibrate/weaken the push/pull of magnetization/magnetism? It can be done. Also no form of NUMetal is used. There is a arrangement that everyone knows, that simulates a monopole effect. Meaning it uses the north or south magnetization only when arranged this way. Now can some one tell me how to ADD to that array, to counter, calibrate, & weaken the simulated monopole effect? So that the gate/sticky point, is weakened to almost weakness of the driving force, instead of being several times stronger? Clue; you can not cancel it out, only weaken it. Also you do not change the distance, because that will always take more energy to do so then the drive of the arrangement could ever produce. Then if you can guess that, then tell me what last mod is needed to push pass the weakened gate.
    I do want to explain so bad, but it is so simple of a layout. Plus even easier to see why it works when you can see it then do the math for why it does it. That it saddens me no one has even tried to do something, or figure out how one can  counter/calibrate/weaken the gate in itself, without adding any energy at all. Everyone always wants to move something. Needing work to do so. Yet there is a different way to calibrate. First weaken the gate, then use multiple dynamics to overcome it. So I'd like to see some GOOD thought experiments to figure it out. Can anyone guess how? Think simple. Though I guess every arrangement we use today, is so simple yet, took man till recently to figure out...
A drawing or scetch would help a lot.



elecar

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Re: Magnet question
« Reply #7 on: June 03, 2013, 08:11:51 PM »
I was hoping Ace would have returned and shown the configuration of the simulated monopole and how to "weaken" the gate.

Check back tomorrow.

elecar

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Re: Magnet question
« Reply #8 on: June 05, 2013, 12:34:46 PM »
Gyulasun  the calculator has been very useful, do you know if the force is the same side to side ? 
EG: as a magnet on a rotor approaches the "gate" Or is there another calculation used ?
Thank you

gyulasun

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Re: Magnet question
« Reply #9 on: June 06, 2013, 10:20:22 PM »
The force side to side depends on first of all the shapes: just think of a cylinder - cylinder or a cube - cube surface 'facing' each other from sideways,  so it can be much different.

For such side forces I am not aware of online calculators and in fact such situation can be rather complex math-wise. I would suggest to get acquanted with electromagnetic simulator softwares, the best 3D simulators in this field cost a fortune but there are 2D for free. See this link on the Finite Element Method Magnetics (FEMM for short) software: http://www.femm.info/wiki/HomePage  And here is another link to see what animation can be done with (its included) Lua script: http://usuaris.tinet.cat/sje/femm/acgen.htm

I have not used this software, some members here already did, you may have seen pictures on some FEMM models uploaded, like here where a toroidal core with a coil on it is simulated in Figure 1 in the center: http://www.overunity.com/13481/maquina-movida-pela-forca-da-gravidade/msg362016/#msg362016  (you can see several photos of the rotor and stator involved there by scrolling above in that thread.)

By the way, I think any such calculation (if you knew how to) may give only a rough approach to such problems, the best is to build a setup and feel the forces with your hand or as TinselKoala describes below... 8)
Even if you buy magnets manufactured from the same 'batch', their strength are not at all the same, there surely are differences between them. Some manufacturers provide service for selecting magnets with gauss meter out of many magnets, for extra money of course.

TinselKoala

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Re: Magnet question
« Reply #10 on: June 06, 2013, 11:15:53 PM »
Back in the Steorn Orbo days I did some very precise measurements of just how much the core's attraction did reduce, when a toroid coil is given a certain current enough to saturate it. It turns out that only a tiny reduction in attraction is enough to make an Orbo-type core effect motor run quite well.
I used a micrometer-adjustable height stand to suspend an accurate force gauge with a magnet in its tip, and mounted this over the toroidal coil, then put a known current thru the coil and plotted the force on the gauge as I changed the distance to the toroid core using the micrometer. Then I would test the toroid on the Orbette 2.0 testbed for performance. Just a few milligrams reduction in attractive force, out of many grams total, was enough to make the Orbette rotor spin well.

The point is, you still have to put energy in to shield or neutralize some attraction, but it doesn't have to be very much at all, and the amount can be so small that it's hard to notice. You would never feel the little force difference I noted above by hand, but it would make that Orbette rotor spin at hundreds of RPM.

elecar

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Re: Magnet question
« Reply #11 on: June 07, 2013, 12:12:23 PM »
Thank you both, I did take a look at the software but it is beyond what I am capable of dealing with. I have built several models and trialed them in the past, but last year I suffered a stroke and now I find myself with time on my hands to start playing again.
I am trying to get by without using any electricity/electrical components in the motor, so a true PMM.
I will construct a model based on my new design but I still fear the cogging and gate will be an issue and I may have to resort to electrical components later.

truesearch

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Re: Magnet question
« Reply #12 on: June 07, 2013, 05:01:53 PM »
@elecar:


It's sounds like you have some interesting experiments ahead of you. I hope you share what you discover here!  :)


You identified the "cogging" as a potential problem, let me suggest you get in contact with "robur" over at Energetic-Forum as his post suggests he has a work-around. . . (Link: http://www.energeticforum.com/renewable-energy/14107-magnetic-motor.html ).


Wish you the best!


truesearch

elecar

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Re: Magnet question
« Reply #13 on: June 07, 2013, 07:03:42 PM »
Thank you, I took a look and it seems he had the same problem "needing 2 shafts" I have got it down to one and will be starting a build in the next 2 weeks.

Here is an earlier one I was playing with.








ace569er

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Re: Magnet question
« Reply #14 on: June 08, 2013, 12:40:45 AM »
   The drawing interests me. Though it also confuses me...Anyways you can get a monopole effects, by two ways. At least, that I know of. One way is to use something   paramagnetic(something magnetic) That contains ether the north or south flux completely. While having the opposite partly contained. The attraction can be made weaker than the repulsion. Not that that has anything to do with what I was talking about. The other way is to simply use a V-gate drive.
   Which is (if center perfectly in the gate) uses only the repel or attract. Even though both poles stay active. They compliment each other instead of countering each other. Like most other arrangements. So instead of canceling each other out and not moving, the V-gate drives to the weakest/strongest point of the flux field. Depending on if using repulsion or attraction. Which is called the gate, sticky point, or lock.
    Now most try moving the drive magnet.  Moving it out of the lock range, is useless. Because you must use more energy to move it out of range. Then more to put it back and even more, to keep it there. Which is equal to or more than, it would take. To just push through the lock. An even smarter approach is the add more drive points to push the stuck arm passed the lock/gate, but the lock is 10x plus stronger than the gate's total drive. Depending on the distance, and degree of change over that distance, of the gate. So to test would need too many extra drive magnets which would have to be at the proper degrees yet far enough away so that there flux fields do not overlap. Meaning that it most be made very large. Also not practical for a test. So one only way is to weaken the gate in itself instead of trying to overcome it. By modifying the gate one can archive calibration.

Now combine both types of issues. Which gets both the simulated mono pole effect of a V gate.  As well as the counter push and pull,(non-single pole drive) to weaken the gates sticky point(lock). Making the lock no longer ten times, plus, stronger than the gates push, but instead, far, weaker than it.  While keeping the simulated monopole effect that drives(and locks) the movement. While at the same time increasing the drive force.
 Making the locking point calibrate-able. Weakening the lock, or if overdone relocating, the lock. So that 11 armatures pushing the 1 can be far stronger than the 1 in the gate/lock. Also to get those degrees, wider then the flux field. It had to be 8 foot around, not good enough.  Unless....I could calibrate the lock, without weakening the drive. Then I figured out how.
 Even though it is 10 times plus stronger then the drive. Depending on the the degree it opens within the length of the gate. After so much, the drive weakens. So Calibrating the lock is the only way to overcome it. Without going very, very large. To make sure there are no two armatures, are in a lock's field at the same time. While keeping the degree separating to achieve The same drive at all 12 points. At all times. So can anyone guess how to calibrate the sticky point? I have almost spelt it out completely...
 Then Just for fun,.... add a overbalance and use Finsrud's design, to till it as it moves. As well as ,some other use of springs, pendulums, & a few other ideas. Of which I have never seen, any of these ideas I have, even partly combined. If even thought of, to hopefully make a beautiful, working, work of art. That has more power then just barely moving. So that some work may be taken from it. I'll tell more if anyone can guess what I mean, with my vague riddle like statements.

P.S. I repeat myself because I made this mostly from cuts & pastes. I don't like writing the same stuff twice. Sorry if it's harder to understand because of that...