charging alnico magnets with rare earth magnets?

[guitar_slinger8]

can all alnico types be charged this way?

[PatrickMahoney]

Hi Guys,

Check the following post for many answers to your above questions:
http://music-electronics-forum.com/t16217/

Peace,
Patrick

[Yves]

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.

Yes, except that the side of the alnico facing north of the charging magnet stack is south. Actually, you may present the north but then the bar will have its polarity reversed once charged (this can be usefull to reverse a ingle coil polarity though).
And yes you need to turn around things then after.

I've made two drawings to clarify:
fig1 is the method I tried first, which gave me inconsistent results. (Imagine, there are spacers to keep the neo mags appart)
fig2 is what I ended up with. The cardboard (thin but somewhat rigid) helps me to remove the alnico "on axis" by pulling it once charged and avoid direct contact (and hence wrenching effect, if alnico slides againts other magnet/magnetic metal surface).
Removing "on axis" was the clue to me, and sometimes if I somewhat "slip" when removing the magnet (due to heavy pull), I may not get full charge. Actually I am thinking of making some jig based on the principle ... just been lacking time for this and since it works quite well like this...

I use stacked neos, because it was easier to source with this size and also cheaper than bigger ones.

[PatrickMahoney]

Hello Yves & tonedeciple,

To quote David King's response to one of my questions about charging bar magnets:

"You want the bar magnetized across the width i.e. the 1/2" dimension. Not through the thickness (1/8" dim) or the length (2.25" dim.)"

Again, please see the postings in the following thread at this URL:
http://music-electronics-forum.com/t16217/

All of these questions are answered, and tons more.

Peace,
Patrick

[Yves]

Hello Patrick,

Hello Yves & tonedeciple,

To quote David King's response to one of my questions about charging bar magnets:

"You want the bar magnetized across the width i.e. the 1/2" dimension. Not through the thickness (1/8" dim) or the length (2.25" dim.)"

Yes absolutelly: that 's what I want, and what I am doing indeed.

What may be confusing in my (rough) diagrams are the arrows: they are NOT figuring the field but the axis through which the alnico is presented to the assembly (i.e the alnico movement during the process).
And that's preciselly what I meant with this all: presenting the alnico by the side (i.e. perpendicular to the magnetizing field, fig1) didn't work for me because the alnico certainly goes through "various magnetizing incidences" when living the assembly.
That's the reason why I ended up with fig2 assembly so that the alnico field AND the magnetizing field always remain on axis.

I hope this helps to clarify my previous post.

[Bill Scheltema]

Charging pups

Here is a little video I did that supports Yves system.

Thank you for that Yves, it does make a more consistent charge. Bill

[psychotech]

Charging your own magnets

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.

I am using the StewMac disk magnets on a plastic clamp and they charge my single coil rod magnets fully and the pups sound excellent. You might be cancelling out the field by using pairs try just one on each side. Just a couple of passes should do it.

[psychotech]

I have a pair of Rare Earth magnets that StewMac sells to charge rods in their Single Coil Kits and they work very well. I have tried to charge bar magnets and the charge never comes up to the level of the A5 in a JB. I can charge an unmagnetized bar and it reads the same as a StewMac pre-charged one. I have Gauss meter and the JB measures almost 50 at the coil where the kit magnets from StewMac measure about 25 directly on the coil. I think the magnets used in JB's could be A8's or overcharged A5's. I have noticed that when someone says they swapped out their magnet in a JB for an A8 they don't really notice a big difference. Does anyone have a Gauss meter and have you compared the readings on a JB stock at the coil and an A8 swapped one at the coil? Have you measured the magnet once removed? I have wound many pickups with magnets from StewMac and other sources all A5's are usually consistent but Jazz and JB I have read have double the magnetism of any typical A5 I have ever seen. I found using a ceramic magnet gets the same coil magnetism reading as the JB but the tone is not the same. Interesing observations but still not sure what is going on. Why are the A5 magnets in Seymour Duncans pickups twice as hot as StewMac's? I took off the tape on my JB and there was some black stuff on the magnet so initially thought they were actually Ceramic and was puzzled by that. I found them to be shiny like a regular Alnico mag on the side once I looked closer. This confused me more because I have never seen Alnico read that hot on my meter. What's going on here? I am about to call Seymour Duncan and ask them.

[big_teee]

It's really not complicated at all.
There are several ways to do it.
Most use the vise and run it through.
I have a couple of small Neos I stack.
I stick one stack to a metal file cabinet.
Stick the alnico to it.
Then I stick the other 2 neos to the Alnico.
Go back and forth a couple of times.
I take the Neos off the middle, not the End of the Alnico being charged.
Another method I use at times, if I want a weaker charge.
I put Ceramics between the NEOs and the Alnicos.
You still get a good charge but a little lighter charge.
Your Mileage may vary!
B_T

[psychotech]

I noticed that using the StewMac rare earth disk mags when leaving the bar clamped in the charging jig left the magnet with much less pull than one quick close pass. Running it 3/4" from the mags produces a reduced pull mag field also. It was repeatable infinitely with exact results. Theoretically you can use this method to get whatever desired strength you would want from any given mag up to max charge for that mag type. These StewMac 1" rare earth disk mags are super strong and should be able to fully charge pretty much anything up to A8 and C8. They have always worked perfectly for charging my singles. They read slightly higher than the stock pups that came with my Fender. They sound fuller and hotter too.

[David Schwab]

Here is a little video I did that supports Yves system.

Thank you for that Yves, it does make a more consistent charge. Bill

I think the difference is the size of your charging magnets from the two methods.

Try putting the longer magnets in the vice. Put two on each side. With your old way the magnets are too small IMO. The new way has better sized magnets. And you have more of them, so you are getting a better charge.

I use magnets like this now when I charge alnicos:



I find then are very consistent from magnet to magnet.