two different magnetic pmms

[chap]

Has anybody tried the magnets out of old hard drives? The magnets are usually the "rare earth" kind, extremely stong for there size(Unless you tear apart a REALLY old drive) and the metal that they are glued to is a very good shield.
I took apart several old 18 gig SCSI drives and couldn't pick up a paper clip on the back side of the shielding metal, while it was all I could do to pull the unit apart! One side of the unit will pick up a 20 pound sledgehammer with no problem.

[grim]

If you grab up the microwave ovens the neighbors pitch on garbage day, you can get cylinder magnets out of the magnetrons that will put blood blisters on your fingers if you get them caught in between attracting mags.

[Jonathan]

Well that's pleasant grim. Thanks for the info chap (hey, I sound British), what shape does the sheild usually have and what it is made of?

[MrTim]

A few days ago I suddenly had an idea for a magnet / gravity wheel and since then I have been trying to think of why it wouldn't work but cant think of any reason why not!
Your thoughts please.
Trev.

The main problem that I see (why it doesn't work), is that the weights don't have enough of an over-balancing effect to overcome the mass/inertia of the rest of the wheel. (Being placed near the hub of the wheel doesn't help either.)
Also, any weights at the bottom of the wheel [5] (I number the spokes of the wheel from 1 to 8, the top being '1', movement being clockwise) act as a 'keel' (like on a sailboat). To overcome this, the weight at [3] must be moved further out to raise the [5] to [7], which, once the [3] rotates down to [5], the 'next' [3] must be even further out, etc.
So unless your wheel is capable of infinitely expanding by a factor of 3, it won't turn. (Note that only the weights at 3, 5, and 7 are used in these examples. The other weights' positions will only horrendously complicate things further.) This is something I've named "Leverage Death Spiral" (Okay, not an accurate term, but it has a nice ring to it.)
If you want to experiment, place a weights at: [7], 1x from axle; [5], 3x f.a.; [3], 3x f.a. (To raise the weight at [5], you will have to move the weight at [3] out to 9x. At [5], now 9x, the weight at [3] must be moved out to 27x, & etc.)

[chap]

The shield material is hard to describe, both shape and material. It is kind of between a banana and a short horseshoe. Sometimes it looks ike some kind of stainless, sometimes I'm not sure what! The really small ones(1-2 gig) usually have really tghin magnets, while the bigger ones have thicker (3/16"-1/4") ones. do you have any old ones to tear apart? I have a dozen or 2 handy. They sell the magnets online at various sites.[/img]

[Jonathan]

Thanks chap, I will see if I can find any old hard drives; I'm really only interested in the shield.
MrTim, I found your post confusing, because Trev's device has only 6 spokes. However, as the version I built has 4, I think what you say would then be easiest to analyse in that case, like you said, more weights would complicate things. First I want to say that it doesn't matter what the average radius the weights that get off-set (the ones creating the torque differential) are at, what matters is the radius differential. Secondly you are right, in terms of the torque interacting with the peripheral weights/magnets, it would be better if the peripheral weights/magnets where toward the center, providing less resistance to acceleration.
As to the leverage death spiral, I don't think that will be a problem with this design (though in some it does occur and I love that name for it), because the problem with your reasoning that it will be a problem for this design is that once one of the weights reached the periphery, you assumed it would stay there until a few degrees above 9o'clock. But this isn't true in this design, the rising magnets start moving inward before they've even reached 6 o'clock(before they've even begun rising). Preferably one would want it to start exactly at 6o'clock, but what can you do?

[VergingOnDone]

http://www.fdp.nu/photobooks/album.asp? ... o%20Movies

Some movie clips on the minato wheel, and apparently this device eventually stops too. Like Finstrud's.

[Trev]

Thanks everyone for your thoughts

"Hey now, that is pretty neat."

Thankyou Jonathan, I thought that myself when it came to me - simple and obvious, like the best usually are.
I think 8 weights would be more likely to work, as for 4 , I wouldn't expect it to overcome the inertia.

"The main problem that I see (why it doesn't work), is that the weights don't have enough of an over-balancing effect to overcome the mass/inertia of the rest of the wheel. "

Mr Tim, I agree that is quite probable but it is a prototype straight out of my head, I'm sure it can be improved upon.
As for the #1 to 8, I also found that confusing but I think I got what you meant, I think you are wrong about it suffering the 'keel' effect, as if you look at the drawing you will see that the bottom weight is already half way up at the 6 o'clock position this will occur due to the complex balance of attraction and repulsion from the N & S poles of the various magnets interacting with one another.

I intend to play around with this idea more and build a test model, I'll keep you posted.

Vergingondone, (or anyone else) if you are interested in the Minato motor I have alot of collected info on it. I've built several models.
Trev.

[MrTim]

Mr Tim, I agree that is quite probable but it is a prototype straight out of my head, I'm sure it can be improved upon.
As for the #1 to 8, I also found that confusing but I think I got what you meant, I think you are wrong about it suffering the 'keel' effect, as if you look at the drawing you will see that the bottom weight is already half way up at the 6 o'clock position this will occur due to the complex balance of attraction and repulsion from the N & S poles of the various magnets interacting with one another.

I use 1 to 8 because my test wheels have 8 spokes (and are numbered clockwise.) And yes, I'm very good at confusing people!
Even though the magnets at 6 o'clock are repulsing each other, and the movable magnet is moved upward, the movable magnet is 'pushing down' with an equal force on the lower magnet (Newton's Third, equal/opposite reactions), i.e. it's 'weight/mass' is in effect still 'resting' on the lower magnet.
Through a hard 15 years of experience, I've found out that any design that suffers from the 'keel' effect (Yay! I've invented some new PM terminology!) will not work. Finding out why things don't work is just as important as finding out why they do work.... (and helps you find a way around the problems too!)

[Trev]

Even though the magnets at 6 o'clock are repulsing each other, and the movable magnet is moved upward, the movable magnet is 'pushing down' with an equal force on the lower magnet (Newton's Third, equal/opposite reactions), i.e. it's 'weight/mass' is in effect still 'resting' on the lower magnet.

I thought about this, but each opposite pair seem to be creating equal and opposite forces cancelling it all out, leaving only the sliding magnets weight imballance.
The only way to tell for sure is to build it.
Trev.

[Georg Künstler]

I don't know, why nobody is rebuilding a working design. The Hamster cage is a solution for a magnetic pm. It seems to me that even a solution is given, anybody tries to do the invention better and alone. Maybe the Hamster cage is to easy to buildt.

[Jonathan]

The guy who built it said it was hard to do, and he obviously hasn't done much with it himself.
Now Georg, please humor me: If we follow the same logic you just said, but applied it in the case of you, who not only claims to know the answer, but consistently tries to take credit for other's ideas, why do you not make a working wheel? Really, I think you are the only one who really understands your ideas, so why do you not build one and show us? Why do you come here with hints and no proof? I know that if I had the answer I would come here only to explain exactly what it is and then return periodically to answer questions and provide proof. This seems to me to be a perfectly reasonable course of action, and I just want to understand why, given that you know the answer, you don't do the same.

[Trev]

Georg,
I was in contact with the man who came up with the Hamster cage motor years ago when I was researching magnetic motors, he told me then that he only got it to run once and then only for 'about 16 revolutions' and could never get it to run after. So do you have a working hamster motor?
Looking at the design it looks like it would easily find a point of equilibrium and stop.

[Georg Künstler]

Hi Trev,
I said I have studied the Hamster cage, and it is a PM. It is hard to adjust because of the right timing.
I found an other construction which is easier to adjust. I can sent you images if you want.


Best regards

Georg

[terry5732]

Magnets are very similar to gravity - but MUCH easier to control! And there power can be easily converted to electricity, which is highly useful! I still think there is hope for a good gravity motor, but am persuing the electric route presently.

http://www.theverylastpageoftheinternet.com/ has many useful and interesting ideas regarding magnets.

I have worn out the first set of bearings on my "motor/generator" and rotor #2 is still whirring after a week continuous running with NO measureable drop in power of storage battery. Unable to quantify outputs accurately with my limited equipment - but looking good!

I have seen lenz's law and didn't like it , so I chose to break the law.