charging alnico magnets with rare earth magnets?

[guitar_slinger8]

Hi everyone, ive readin around this whole forum for weeks after i decided to start winding my own pickups, ive already re-winded some old epiphone humbuckers i had lying around just to get a feel for it, and now im moving on to winding my own humbuckers from parts from mojotone.

my question is, are rare eath magnets enough to charge the alnico bars?

[David King]

Hi Guitar-slinger and welcome to the little den of malfeasance.

Your question comes up here quite regularly. A search will get you piles of info, some of it accurate. Basically the answer is yes. You'll need some good sized Neodymium blocks and a pile of iron chunks but you can then efficiently charge any of the Alnicos I-VIII.

[guitar_slinger8]

thanks david.

so i was thinking of setting the magnets in a vice and just passing the alnico magnets in between the rare earth magnets 2 or 3 times

[David King]

That will definitely get you a charge. The only way to know for sure if you're getting close to saturation (full charge) is to check it against a known magnet with a Gauss meter. You might not like the tone of a fully charged magnet so don't sweat it too much unless you aren't satisfied with what you are hearing.

[guitar_slinger8]

well, ive been looking at gauss meters as a future investment, but seeing im just beggining they are to expensive of an investment at the moment, ill definetly just experiment with passes throught the magnets im definetly not worried about full charged magnets, cause im aiming for an aged magnet sound which will probably be more mellow like a paf style humbucker.

[copperheadroads]

that what i usually do with charging alnico. those stew mac neo magnets .leave them in the plastic cases & stick them in the jaws of my vise just like they are

[guitar_slinger8]

copperheadroads , how many passes do u do through the magnets?

[copperheadroads]

3 to 4 with as little space as possible .without a gauss meter which is next on my list it hard to get a good idea how much it takes to fully charge a magnet

[Joe Gwinn]

3 to 4 with as little space as possible .without a gauss meter which is next on my list it hard to get a good idea how much it takes to fully charge a magnet

If the neo magnets are large enough and the magentic circuit adequate, only one pass is required to fully charge (saturate) the alnico.

If not, no number of passes will achieve saturation of the alnico.

Some people prefer to undercharge the alnico magnets.

An experiment showing achieved alnico charge versus number of passes could be interesting.

[David King]

If not, no number of passes will achieve saturation of the alnico.

This has certainly been my experience.

[Yves]

Well, I never really understood how you could charge properly alnico rods (no to mention bars) with the Stewmac Neo magnets which seems small to me for the job.
Though it seems to work for some people...

I use 4 neo magnets 4" x 1/2" x 1/2" Thick, Grade N42 stacked together.

In the first place, I used them stacked by pairs and used to present the alnicos (wether bars or full single coil bobbin assembly) in between the space between the two pairs, with proper spacers between the pairs.

Actually this gave me poor result and inconsitent charge. My opinion with this is that the alnico to be charged shouldn't come from the side of the charging assembly because the field gets distorted when the alnico is removed from there by the side. instead I believe the alnico to be charged should be presented through the axis of the magnetizing field.
I ended up stacking the 4 neo mags and I present one alnico end once to the north pole of the assembly remaining in the axis when removing it, and then the other alnico end to the south pole still remaining in the axis.
I use some cardboard to avoid direct contact and hence wrenching effect that tends to degauss alnico.
I've checked this with a gauss meter and this method gives me full charge, consistent results.

Then, if necessary, I deggauss the alnico charged this way to watever value I want with a ceramic bar.

FWIW.

[guitar_slinger8]

thanks guys for all the help,
im gonna try stackin some neo mags and separately pass the alnco bar trough each side separately like yves discussed.. i will let u know guys how it goes

[David King]

If you have a drill press or a "fret press" (1/2 ton arbor press), you can set one magnet on the table and attach the other to the quill or ram. That way you can lower or lift the magnets apart "on axis". You benefit greatly from completing the magnetic circuit with lots of cast iron.

[guitar_slinger8]

yeah sounds like a good idea, i just dont have a drill press, darn i which i had one

[tonedeciple]

I ended up stacking the 4 neo mags and I present one alnico end once to the north pole of the assembly remaining in the axis when removing it, and then the other alnico end to the south pole still remaining in the axis.

I'm trying to visualize this. Is my illustration correct? Obviously, the neos and the alnico would be turned around to expose the south side.