Magnet size and shape?

[coldspot]

I have a question about MAGNETS.

When building a gen or alt.

Does magnet size and shape have to be the same?

I gutted five old hard drives today, three where same mfg and like sized even!!!

I got in magnets: three sets, (of two) different sizes n shapes!

                  One set missmatched size and shape!

                  One set of four matching!

Do I need to keep looking? (I am running out of old drives).

Thank you to any replies!!!

[ghurd]

There is no such thing as too many hard drives!

Maybe something in these 2 stories will help.

http://www.fieldlines.com/story/2005/11/19/193957/27

http://www.fieldlines.com/story/2005/9/24/152446/359

G-

[coldspot]

THANKS Ghurd!!!

"There is no such thing as too many hard drives"

 on this I agree but, I'm now out of them. Gutted last one a moment ago

singe mag,close to one pair but reverce polls.

Local shops don't like me much being the comp ya know!!! (home guy doing 4 fun n cheap)

maybe one would let some go I'll ask today, only other friendly shop moved 35 miles away and haven't talked to him 4 awhile.

I also bought some copper 1/2" tube last night for solar water heater $7 10' seems cheaper that coil, will be using HD disc's as reflecters, have a bunch saved from

earlyer HD guttings but alas the mags got a new diffenert life and now wishing I'd saved more of them!

Also need to find a "T8 and the next couple sizes down bits" broke a new left hand drill bit late last night, (%&!@#$^%$%%)!!!

I'll keep a eye on the stories you listed

THANKS again!!!!

[electrondady1]

my harddrive collection efforts have slowed down . the stores i use have had none for 2 weeks. i used what i had to layout two rotors, 16 poles each using two or more layers of neoes . did the best i could to get a consistant 6.3mm on one rotor and 5.4mm on the other .test coil results have been encourageing! these are brake rotors i had reground. there only 9.25" in dia.  there is enough room to add another stack of mags on each pole to get longer legs.




 while waiteing for more hard drives to show up i formed this 14" automatic trans flexplate rotor with 32 poles, using three ceramic mags per pole.

when using these oddball mags , ive just tried to place them inside a defined space.  the plan is to form the coils to fit that space and then accept whatever current the individual mags can produce.

[ghurd]

Harbor Freight reatil stores have a small torx bit set, maybe 6, in a red rubber holder. for $5? Electronic goldmine has a better 25(?) piece security bit set for $5

Need a T-10 too for the outside, but you know HF doesn't have a T-10 in the whole store?  T-15 and up, T-9 and down. Funny.

[kitno455]

odd coincidence, i just tore down my entire pile of dead drives two nights ago, 12 in all. two of them were big old 5.5 full height scsi from the mid 80's, with bigger mags. have not been to any stores, but i saw in the paper that a new factory is openning here in town to do just this- tear open dead hard drives and get the heavy metals out. i bet they will buy up any freebies...

out of the entire stack of mags from the 3.5 inch drives, they seem to come in three major thicknesses, making using them difficult. i dont have enough of any one thickness to make a rotor with a small air gap. perhaps some sheetmetal shims would help?

most of these have two poles on each face, so you have to crack them if you want to get some space between.

i think the size/shape of hole in the coil should be similar to shape/size of mags. any bigger adds resistance (cause of longer wire length) and any shorter causes both legs of coil to be over mags at same time. slightly heavier wire makes up for the former, but increases the size of the airgap.

fudge it by making little piles. or send them to me

allan

[TomW]

Guys;

I was reading these HD threads and had a possibly  bizarre idea on how to use them as is with a probably near impossible to make coil.

Ok we want to have a + over one leg and a - over the other but we have a magnet with 2 poles on one face.

Theoretically, I suppose you could wind coils to fit this actual configuration by laying the mags along an arc rather than a radial of the disk. This would likely result in some very narrow coils.

The idea that popped into my head was to wind "figure 8" shaped coils then you could pair up mags on adjacent radial lines or go dual rotor. The "flipped" lower bits would see the opposite polarity of the upper.

I am not a builder myself and this would be beyond the ability of my fingers to do. I just toss it out for either your amusement or as an idea you might see merit in trying.

Probably crazy and unworkable but to me, at least, it seemed like it might work "in theory".

Cheers.

TomW

[kitno455]

yeah- i actually thought of that. in either case you have very short coil legs, and lots of end windings. we have so little flux here due to the thinness of the mags, keeping the coil short seems like a good idea. i suppose you could put two concentric rings of these things, that might work!

allan

[electrondady1]

as far as using the mags as is , in an ordinary dual rotor the coils are exposed to four seperate poles. that is to say two on the top and two on the bottom . in the case of using the hd mags the coil would be exposed to 8 poles. i have not done the experiment . but i think there could be only one of three possible effects ether the coil produces 1/2 the current , two times the current , or the same current.
 the effort to cut the mags up is minor .
 i can't help but think that there is a lot of flux loss when there is 0 gap between the poles .  why would the flux travel through the air gaps and coil to the other rotor when an opposite pole is so close?

[electrondady1]

coldspot, this is your post, hope it's working for you. as far as using different size mags. what i found when doing a test coil on these hard drive mags, as the coil moved over differnt poles, the voltage output  would vary.

it seems a shame(one of meny i guess) but there is no organized effort in this area to recycle computor waiste. it all goes to the land fill.  

[TomW]

allan;

Yeah, I figured if it was workable someone would be doing it or tried. I just get ideas and dump them raw and wait for the downside to be pointed out.

Interesting anyway.

Cheers.

TomW

[ghurd]

The HF 6 pc bit T-5 to T-9 #93316.

The EG 32pc 'security' bit G13712, $3 until 12/29/05.

Usable, but neither are very good quality.

[coldspot]

Thanks for ALL the replies!!!

Bummer about the lack of actual use of these mag's.

So, the mag's you can buy, (HERE), are single pole? Like you order 20 and get

10 South and 10 North? Is this what I'm learning?

Or are they just like magnets I'm familier with and have a N and S just one side is

N and flip it over and over side is S?

?

Thanks

[dinges]

If you invent (or buy) a single-pole magnet, you'll be elegible for the Nobel Prize for Physics.

Many physicists are researching the matter, but so far the mono-pole (single pole magnet) has not been found, to the best of my knowledge.

So far, every magnet has a north pole and a south pole. Don't believe people who say otherwise (unless they've just been awarded a Nobel prize ;-) )

Peter,

The Netherlands.

[ghurd]

You mean 'single pole per face'.

Flip them over to get the other pole up.

Many, not all, of the HD neos have 2 poles per face, like

up top

N / S

-----

-----

S / N

down bottom

Someone has a 20" box fan blade on a single rotor, single phase, 20 tooth saw blade with 20 poles of HD magnets with 1 pole per face. 20 coils wired 10 in series, in parallel with the other 10 in series. IIRC

It works. Keeps his cabin battery full enough for his weekend use.

Found it the lost it. 'Net problems right now.

Quote

""well, what is there to tell. . .

The bearings are the motor from an old 5.25 inch hard drive.

The magnets are from maxtor hard drives.  Those little kidney--bean shaped magnets that have only one pole on each face. (takes 4 of them per drive instead of two like with others.

Those magnetsa re mounted on the teeth of a 5 inch circular saw blade.  20 teeth, 20 magnets. . .

The coils (20 of them) are centered on the magnets.  The blade and the thing it is mounted to is the armature of the 20" box fan.

It is two sets of 10 coils in series, wired together parallel.

It'll put out about 40VDC in a stiff wind.

It is keeping two 6V golf car batteries charged at a remote cabin. (cabin has a incandescent over the sink and a flourescent over the table and that is all it does, but works great.

Keeps those batteries at 12.8V after the weekend drain to about 12.3. . .

Anything else?

Doug""

There was a photo. Can't find it.

Posting while I still can...

G-

[coldspot]

Ahhh..

I was pretty sure mag's had bolth but was speed reading posts and typed a quicky reply, BAD on me!!  LOL

I found the "Torx" bits at Homedepot

Husky # WF74502

$5

t4,t5.t6.t7.t8.t9.t10 and t15

Super Cool Tool, 4 dbl ended bits, 3 store in handle.

When I get more HD's things will teardown quicker now and I'll get out a compus

to see what mag's I'm getting, was trying to get enough for a "Lentz2" Mini type

but have a idea I wanted to for improved performance.

I might just order some and go from there, I now, (because I found this board)

way to many projects started, (I was bad before this and now WAY OUT THERE).

I've got 4 PM units started and have built a bunch of stepper motor ones to prove to my friends that I am crazy'r than they think!

Thanks