Centered solenoid design

strantor

Joined Oct 3, 2010
6,782
Interesting. I wonder what the difference is between a permanent magnetic field and an electric magnetic field that could explain the difference. In my mind, our experiments are essentially the same.

More experiments should shed some light. Magnet wire and magnets should be here tomorrow,
 

inwo

Joined Nov 7, 2013
2,419
It may be my explanation that's wrong.

That is what happens with iron rod between magnets.

With end to end magnets thru the core it's stable when in the middle. either polarity.

When pushed off center, one polarity pushes magnets out of coil. The other tries to hold them centered.
 

strantor

Joined Oct 3, 2010
6,782
Do you think the wound field design could be improved (made more powerful) by adding an iron core to the inner coil and an iron armature to the outer coil?
 

Thread Starter

#12

Joined Nov 30, 2010
18,224
Certainly. The basic principle of adding iron is that you can concentrate a lot more magnetism into iron that you can into air.
 

strantor

Joined Oct 3, 2010
6,782
Oh, #12, nice to see you tuning in. I was thinking today about what I'm experiencing with the attraction/repulsion from center anomaly, and I can't wrap my head around it, nor can I really wrap my head around what you proposed in post #1, but I think there's something going on here that relates to the center of the magnetic poles. Since your design strives to relocate the end of the poles to the center, I suspect you might have some insight into the mess. Can you explain/do you understand what I experienced, and did you already know that would happen, and is the purpose of your design to combat it?
 

Thread Starter

#12

Joined Nov 30, 2010
18,224
I watch, but I posed a question and it seems we don't have any magnetics experts here.:rolleyes:

One of my points is that you can move and concentrate magnetic flux with iron shapes. The shape of the resulting field is limited only by your skills and imagination. That's about the end of my knowledge base. I can't even understand motors! Current limiting shunts in a microwave oven transformer? Might as well be talking about fitting tennis shoes on a pig.
 

strantor

Joined Oct 3, 2010
6,782
it seems we don't have any magnetics experts here.:rolleyes:
I know! I find it very odd. It seems this would be the place to find one. I think 8 solid hours of playing in the garage with coils, neodymium, and iron filings might make me the leading AAC expert in magnetics! Couple that with some half-ass research, and I'll be unstoppable. Just you wait, as soon as amazon gets their **** together and send my stuff... First time Amazon Prime has let me down.
 

inwo

Joined Nov 7, 2013
2,419
Here is a picture of two rod magnets made up of smaller segments.
Two rod forced together N to N in shrink tube. (shoddy job)

There is no neutral position in center.
One polarity pushes right until left side is flush.
Other polarity pushes left until right is flush.
 

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Thread Starter

#12

Joined Nov 30, 2010
18,224
Post #48 looks like a very good idea.

Maybe not the finished design, or the best way to do it, but it moves both ways. Worth studying.
 
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inwo

Joined Nov 7, 2013
2,419
Please do let me know if there is something to test.

Please do not take it too seriously.:)

Speaking of knowing nothing about magnets.:eek:

Isn't there something about this configuration that is bad for magnets?
Old PMs had keepers!

ps.
Too slow...............
 

Thread Starter

#12

Joined Nov 30, 2010
18,224
Yes, there is a strong caution about forcing magnets into opposition.
But he got it to move both ways!
Design task: Find out how to do that without setting the magnets in a self destructive configuration.
Oh, wait...that's what you've been doing all along.
Never mind. :D
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
Problem is, it holds 2 permanent magnets in opposition, which by my weak understanding, will drain them. One more good reason to go with coils.
Now most magnet materials are Rare Earth or Neodymium and replaced the old style ferrite and Alnico types that needed a keeper.
I have some from a Large servo motor I use in the shop for temporary positioners and still have to virtually pry them off a steel surface.
Max.

 

strantor

Joined Oct 3, 2010
6,782
Right, newer magnets like neodymium hold their charge for (effectively) forever and do not need keepers like alinco types. They would stay clamped onto your steel surface and your greatgreatgreatgrea.... grandkids would need a chisel to get them off. But that's not the same as being held in opposition with another magnet. Im worried that, being a double acting actuator, electromagnetic fields might weaken even neodymium types over time, which is why I'm seeking a solution that doesn't include them. One epiphany I had, but I'm still not convinced of it, is that a permanent magnet solution would work just fine as long as the electro magnetic forces are working with the permanent magnetic field more often and with more force than they are working against. As in, I orient the magnets so that in the most common mode (grasping) the forces are attraction forces, not repulsion forces. But, with inwo's revelation about the schnoodling magnets, I don't even know if that will be possible.
 

Thread Starter

#12

Joined Nov 30, 2010
18,224
In my opinion, a single coil with reversible polarity working a single magnetic gap in 2 directions would be the cats pajamas. However, 2 coils that each attract instead of repel would be sufficient. Still, I speculate you are too timid about permanent magnets degrading over time.

It is true that grasping is much stronger and more used than hyper-opening of the hand.

Do you have machine shop tools? Can you make iron parts? Rods, hollow cylinders? Sections of curved plates? I fear you are doomed without ways to make shapes out of iron.
 

strantor

Joined Oct 3, 2010
6,782
I have 2 lathes, and one of them works. I think I can put the pajamas on the cat. I just have to invest in the proper iron; from what I've read, it seems almost not worth the time if you don't start with the right stuff, and the right stuff is pretty specific and not that cheap.
 

Thread Starter

#12

Joined Nov 30, 2010
18,224
If I made a "perpetual motion" motor out of repelling neodymium magnets, what tune would you sing then?
You went right over my head with that one. Are you saying there is u-tube evidence that modern magnets degrade over time?
 

inwo

Joined Nov 7, 2013
2,419
Maybe someone could explain how this works.:confused:
Drywall screw with two button magnets.
Sub-C cell to left. Hidden magnet to right supporting the armature.

Built it one day when I was bored.
 

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strantor

Joined Oct 3, 2010
6,782
You went right over my head with that one. Are you saying there is u-tube evidence that modern magnets degrade over time?
No, I'm saying that theres youtube evidence you can arrange permanent magnets around the circumference of a disk and by applying repelling magnets around the outside you can make it spin. Free energy nuts use this to claim that they can power their homes off this free energy generator. Catch is, as soon as you start the thing spinning, it starts depleting the magnets and by the time you drain them down to nothing, you've wasted hundreds or thousands of dollars on neodymium magnets and the energy that you harvest from the short lived generator is FAR less than what it took to create the magnets, since magnet creation is a very inefficient process.
 
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