Using small magnets ganged up

[ruddycrazy]

G'day Guys,

           I can blame one guy for my dilemma on the following question. The 4kw motor conversion I'm making will need some sort of braking and with the guys at work we are talking about dynamic braking. But in reality for a wind genny the KISS principle is always the best as less parts can wear to cause an early failure.

Now I do have 200 off 16x13mm N50 round nickle plated Neo magnets here, by ganging 8 off in a 4x2 orientation would simulate a 64x32x13mm rectangular magnet. Would the spacing in each magnet spacing cancel out or would it not make any difference. I have not seen any projects on this forum where smaller round neo's have been ganged to make one magnet.

As these magnets cost under $200 I would be keen to scrap my 4kw conversion and just make a dual axial flux genny. Using smaller mag's to make one big magnet may have benefits but this idea is out for criticism.

Cheers Bryan  

[FishbonzWV]

Bryan,

I've done several conversions using this process.

Here is a thread about doing one.

http://fieldlines.com/story/2009/3/13/233643/638

But, I did change the way I attached the mags because of the magnetic attraction of the JB Kwik.

The last two I did, I used super glue with accelerator (you will need it) to adhere the mags and then used a two part epoxy to fill the gaps between the mags and the poles.

The next ones I do I will put enough epoxy to cover the mags also and then I will not have to use the fiberglass covering.

The 'flux concentrators' make attaching the mags so much easier to work with.

Before you start, index mark all of the mags because they have a tendency to flip, I just used a Sharpie to put a dot on all the N poles...quick visual reference.

Bonz

[tecker]

When you mount two magnets close there is a scalar pole that develops that  can be charted with another magnet simply check for variations in the pole checking repulsion then turn the magnet sideways and look for the slightest variation generally if there is no core material you need a closer spacing as copper doesn't induce quite as well in a scalar wave .Copper  develops a like pole and there is no current but you can see a large spike in a dense repulsive field . If the field is attractive in the working area gap  your good the only thing that might suffer is the magnetic circuit in your backing material .

[zap]

"I have not seen any projects on this forum where smaller round neo's have been ganged to make one magnet."

zubbly (RIP... we miss ya buddy)was an expert at motor conversions and did exactly what you're asking about.

A search here for "zubbly rotor" will give you many results of his work and the help he provided for many here.

http://www.fieldlines.com/story/2007/3/13/214531/690 is one and here's one of his rotors.

Some of his work is also published elsewhere on the net.

http://reresource.org/User%20Pages/Zubbly/

[FishbonzWV]

Bryan,

After rereading your post I take it you want to use the rounds to make a large mag for an axial.

I haven't seen that many put together to make an axial.

BobShau did the T thing with only two.

Just a swag but I would think that using a steel based epoxy would help in making a complete magnetic pole.

[electrondady1]

don't use a steel based epoxy!

 it will crawl from the crevices to all over the faces of your mags

then you will have to remove it .

[FishbonzWV]

Ed1,

It's not really that bad.

I've used all three JB products on mags.

The standard JB Weld really crawls and takes too long to set up.

JB putty won't squash out from under the mags.

JB Kwik is just right. Sets up in about 5 min.

Cleanup is easy if you scrape it off right after it sets up and isn't hardened.

If you let it harden it IS a pain to get off.

Bonz

[tecker]

That's really not the issue I found the epoxy separates and the part that is the binder is too slight . They pop right off

[FishbonzWV]

Well tecker,

I've used the JB on over two hundred mags and I've never had any pop off.

In fact I've had to remove about twenty mags that I had installed with the JB and it was a task to remove them and clean them up.

The JB has good tinsel strength but poor shear strength.

If the mags get whacked from the side then they will come loose.

I went to liquid epoxy just to get a contiguous pour to bind all the mags.

Bonz

[electrondady1]

"It's not really that bad."

oh yea !

it was a mess on mine !

it was about six years ago but i still remember scraping the stuff off with a razor blade

and then removing all the little bits that wanted to stick

it wasn't jb what ever it was lepages