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graduating to harddrive neos
By electrondady1, Section Homebrewed Electricity Posted on Sat Nov 19th, 2005 at 07:39:57 PM MST
questions regarding magnetic flux

up untill now, all my experiments have been with ceramic mags.(free, and easy to manipulate).i feel i'm begining to understand(thanks to this discusion board) how the various components work together to produce current.
in responce to mr.koos post, i began visiting local computor repair shops. broken hardrives are free and the stores are only too happy to be rid of them.
in order to best utilize the 60 little neos i have collected i have questions:
1/ is it necessary to cut them up? using them as is , with two poles per mag would produce a current but my instinct is that it would be half of what could be harvested if the mags were cut and flipped to form a single pole each. ive searched the archives and found only a coil layout diagram but there was no output figures.
the mag spacing / coil shape did not appear very efficient the leg lengh coil width ratio looked wrong .
2 hiker has posted a project where he used hd neos to resurface ceramic mag rotors and increased the power output. this is tempting. but a have observed that there is less effort required to move(slide) a hd neo placed on a pole of a ceramic mag rotor than over a bare steel rotor( that is surprising to me) .with out a gauss meter i am curious as to wether there is more available flux from the hd neo by itself or from a hd neo with a 1/2 " ceramic beneath it?
standing here in my raincoat with wet tile saw, awaiting any replies.
thanks, shawn

graduating to harddrive neos | 16 comments (16 topical, 0 editorial)

Re: graduating to harddrive neos (3.00 / 0) (#1)
by willib (willibur at comcast dot net) on Sat Nov 19th, 2005 at 12:58:44 PM MST
(User Info) http://www.njwind.com/webcam.html#

if you have 60 , why not stack them , i know that they are very thin,about 1/16" , if you stack them till they are about 1/2" the magnstic flux will be increased considerably !
Carpe Ventum (seize the wind)

Re: graduating to harddrive neos (3.00 / 0) (#3)
by electrondady1 on Sat Nov 19th, 2005 at 03:23:46 PM MST
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yes stacking them up would help a lot but i will concentrate on covering the pole surface area first. apon further testing i've come to the conclusion that adding the neos to the existing ceramic mag rotor would increase the flux level over and above that from the neos alone so it would be an advantage to me to cut them up and use on the existing rotor. rather than begin a new set.

[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#2)
by motorhead2 (MarkE@newlondonwi.org) on Sat Nov 19th, 2005 at 01:13:30 PM MST
(User Info)

I wouldnt skimp on magnets.Their the bread and butter of the gen.
Mark

Re: graduating to harddrive neos (3.00 / 0) (#4)
by electrondady1 on Sat Nov 19th, 2005 at 03:37:51 PM MST
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your absolutly right,i feel good about rescueing these little mags from the waste stream . but how practical they are to use when you consider the time involved in obtaining them and the design limits imposed by using reclaimed material

[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#5)
by pyrocasto (pyrocasto at hotmail dot com) on Sat Nov 19th, 2005 at 04:00:55 PM MST
(User Info)

Well if you're like me and enjoy doing it, and have nothing better to do anyway, then you are set! I need to go around some local computer shops and ask. I've done my rounds for microwaves mags, and have enough to do a dual rotor genny. Time to build up the harddrive mags now. :-D

[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#6)
by electrondady1 on Sat Nov 19th, 2005 at 05:11:24 PM MST
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a very interesting bonus in the process of dismantling the harddrives , one of the most efficient bearings, (motor), ive ever run across. all squared up and attached to a mounting bracket. since it's my intention to build a lot of small vawts i can use them.
there is an issue with the hd neos that complicates there use, it seems there are at least four main thicknesses used in there industry. i'm thinking it would be possible to cut a releaf in a rotor disk to overcome this drawback and present a level face to the stator.

[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#7)
by jimjjnn (jimjjnn at yahoo dot com) on Sat Nov 19th, 2005 at 07:07:20 PM MST
(User Info)

Those different thickness HD mags also have different strength magnetism so you have to give that a thought ,also.
Jim Denver,CO
[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#10)
by electrondady1 on Sat Nov 19th, 2005 at 09:23:32 PM MST
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yes it's rather complex,one rotor could have a different size mags than the other . in order to build the sort of genni i'd like it might take a bit more time. and a lot more harddrives.

[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#9)
by ghurd on Sat Nov 19th, 2005 at 08:54:45 PM MST
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A couple thoughts.
Don't stack neos and ceramics. The ceramics will lose.

While stacking only increases the magnetic power (and output) by 20%, and doubling the poles increases the potential output by 200%.

But those are thin, and the airgap should be less than 150% of the magnet thickness per pole. So I figure they must be stacked or the stator is too thin to work with.
Who can make a usable stator that thin?

If the magnets are only 4 different thicknesses, somebody got lucky.
Some have 4 mags, 1 pole per face. Some have 2 mags, 2 poles per face. Some have 1 mag, 2 poles per face. Some are long, some short, some wide or narrow, or thick or thin. I have not noticed any standard yet.
Hint: The older and smaller the better, as in under 100megs, have 2 big fat thick neos.

I'm working on a HD gennie now but the HDs are not flowing my way fast enough. Had time to think. There were supposed to be 10 HDs today, ended up with none.
I'll decide the single or double rotor, poles and diameter when I give up waiting for more HDs. That will not be long.
So far there is enough for a single rotor 8 pole.
The number of magnets per pole is 2 to 7 to get about the same 3/8" thickness.
Coil is 3/4" high. The coil hole is 3/8 to 5/8", but most mags are 5/8".

My plan is a looking like single rotor 8 pole 12 overlapping coils.
This morning, expecting a pile of HDs, it was dual rotor 8/6. So who knows?
G-

[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#11)
by electrondady1 on Sat Nov 19th, 2005 at 10:25:11 PM MST
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gurd,i've got three stores saving them for me . i drop in every two weeks. some times you get 5 some times you get 15 . i was given two very old ones that have no neos at all they used stepper motors to control the position of the disk reading devise.
you think the neos will hurt the ceramic mags over time?
it sounds like your 'gonna use them as is two poles per mag.

[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#13)
by ghurd on Sun Nov 20th, 2005 at 09:15:24 AM MST
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I broke them in half because I have some 1 pole per face also.
There was a HD story (by mrkooo?) where UGL suggested how to use the mags whole.
Long ago there was a story about stacking neos and ceramics. People who know more than me said the ceramics will be damaged.

I do have good magnets, but they are a little large for this project.
G-

[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#8)
by Clifford on Sat Nov 19th, 2005 at 07:58:59 PM MST
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All magnets have two poles... N and S.
Electromagnets are the same... N and S poles.

If you cut a magnet in half, you will have two half magnets and each half will likewise have a N and S pole.

I haven't torn apart any HDDS lately, so I am not sure what the magnets in them are like. I was tearing up a VCR lately. In it, it had what appeared to be a circular magnet with multiple + and - poles. Perhaps that is what you are refering to.

I don't have a gaussmeter here myself. Perhaps you could make a primative one using an old balance and measuring the force it requires to separate two magnets, a magnet and a piece of metal or such. Could also start with a spacer to reduce the force.

As far as Neo magnets... you will find links for them just about everywhere. E-Bay, and on the internet.

Small magnets are quite cheap, and you should be able to get 100 or so 3/16" cubes or similar magnets for $10 or $20

A few things to keep in mind when stacking magnets...

If you stack groups together....

End to End:

[N S][N S][N S].... I am not convinced that stacking more than perhaps 2 together make a huge difference, especially if they are long and skinny. Perhaps "Shielding" would help. In a sense, I think the outer coating of the magnet will help homoginize them...

Now... say you are wanting to increase the force of attraction of the magnets... (force to induce a current)....

If you have 16 small magnets stacked next to each other, they will try to orient themselves as:

Top Face
NSNS
SNSN
NSNS
SNSN

Bottom Face
SNSN
NSNS
SNSN
NSNS

The problem is that they would kind of cancel each other out.

You would be much better if you could orient them

Top Face
NNNN
NNNN
NNNN
NNNN

Bottom Face
SSSS
SSSS
SSSS
SSSS

Thus, together they would all act as a much bigger magnet.
Of course, there would be many forces pushing them apart too.

Re: graduating to harddrive neos (3.00 / 0) (#12)
by electrondady1 on Sat Nov 19th, 2005 at 11:34:23 PM MST
(User Info)

hello clifford, the magnets inside harddrives are kind of strange , they are sort of kidney shaped and have two poles on each face. when you cut them in half you get two mags about a big as your fingernail and somewere between 1mm-4mm thick. i know the induction motors they use in vcrs. . the one i had was about 4" in dia and had eight poles . i stuck 8 little coils underneath it and pulled about 6 volts out .this last one i made has 16 poles on three 10" disks and two stators with 12 coils each.for three phase. on the outside rotors i used four mags per pole and on the central rotor i used two layers of five mags per pole. you can get the ceramic mags to stick next to each other if you hold them in place while the crazy glue sets up.

[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#14)
by mrkooo (mrkooo@hotmail.com) on Mon Nov 21st, 2005 at 08:02:05 AM MST
(User Info)

Hi, electronday, I´m looking forward that you finish you HD genny and hope you get good power from it. It will be very usefull to me.

I stack 4 half HD magntes in my gennny, total thick +-0.25", I think that is better to make a bigger pole with two o more half magnets side by side and then stack 3 or 4 of them in order to get a longer pole and have a longer section of the coil that cut the flux in 90 degrees, but for do that I think I will need 100HD.

Another problem is that is very difficult to get the same total thicknes when you stack the magnets and that affect the precision of the air gap and performance.

Now I charging a battery bank of 150amp with the HD genny and with a dump load controller, not connected the inverter yet, hope do it this week.

I have like 50 HD boxes, motors, bearings and I dont want to do something with them, but I dont know what. I feel bad trowing it to the garbage.

Franciso

Re: graduating to harddrive neos (3.00 / 0) (#15)
by electrondady1 on Mon Nov 21st, 2005 at 03:12:28 PM MST
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hello mr. kooo,
i was hoping you would notice my post. i think most of the problems with the hd neos can be overcome if you have a lot of patience .
i think you are correct about the shape of the coils . i have in mind, 3 or perhapse 4 half magnets to make the shape of one pole. i beleave i can get the machine shop that makes my rotor disks to cut the disks in small steps . so that the thickest magnets could be placed on the outside edge .
yes a lot of hds will be needed, i got only 5 more today .
i have noticed something already about harddrive magnets, they are much cleaner to work with and much more powerfull than ceramic mags.
i have saved and seperated all leftover parts as well , electrical boards, aluminum cover pieces and of course, the motors,when i begin buying large magnets i will still use them as bearings
congratulations on charging a battery.
there is a devise known as an MPPT charge contoler that i need to find out about.

thanks for commenting,
good luck
shawn

[ Parent ]

Re: graduating to harddrive neos (3.00 / 0) (#16)
by ghurd on Sat Nov 26th, 2005 at 05:56:05 PM MST
(User Info)

Perhaps a layer or 2 or 3 of HD body steel can be placed under the shorter magnet stacks, to complete the magnetic circuit and get an even air gap.
G-

[ Parent ]

graduating to harddrive neos | 16 comments (16 topical, 0 editorial)

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