Magnetizing / degaussing with neodymium magnets

[Marco Pancaldi]

Hello,

I've searched the forum but I've found lot of generic infos and not much detail, for example:

the common advice is to use disks on a vise (maybe two of these for each end) as for example (sorry for Italian description and metric values, the images are clear enough):
Anello Ø 20,0 x 4,5 x 4,0 mm N42 Nichel - con riduzione

But someone says that neo disks are not enough powerful to fully charge A5 rods, so what you think of using neo cylinders, "attaching" them carefully at rod's both ends:
Cilindro Ø 8,0 x 30,0 mm N45 Nichel - aderenza 4 kg

And, what about "play" with smaller cylinder to try selective "degaussing" on the mounted/playing instruments?
Cilindro Ø 5,0 x 25,0 mm N40 Nichel - aderenza 1 kg
Cilindro Ø 6,0 x 30,0 mm N42SH Nichel - 150°C - calamite.org

Finally, I was from longtime tempted from this flux-paper, to visually verify the magnetic field:
Flux-Rilevatore rende visibili i campi magnetici - 75x75 mm
Can it be useful to check a pickup magnetic balance between poles or is it not enough sensible/accurate?

Thanks
m.p.

[Peter Naglitsch]

I have not had any problems charging rod magnets with simple disc neos. If you are worried that the power isn't enough, maybe try these:
Quadermagnet 40,0 x 10,0 x 10,0 mm N42 Nickel - hält 13,5 kg
Thats what I use to charge magnets today. Two in a vice, a thin sheet of plastic glued to the surface to avoid bumping into the neos and you can even charge ferrite magnets. At least bump them up a bit if they are already charged, but not to full power. But be careful. Those are some really powerful magnets. You do not want your skin pinched between a pair of those. Ask me how I know...

And the flux paper is a handy tool to visualize ay the magnet layout in an epoxy sealed pickup, but if you need better info n magnetic balance, you need a gauss meter, like the AlphaLab Model 1 or the echtech. Video on the AlphaLab meter: I have a combo version with a selector between high and low setting. I don't know if that is still available:
http://www.youtube.com/watch?v=gE29puNc6pQ

[rhgwynn]

I use 2 - 1"x 2" x 1/2" N52 grade neos to charge mine. They work just fine. But do be careful; these magnets are not toys. They can even shatter if they attach too hard. I use ceramics to degauss; works great.

[Joe Gwinn]

Neos are strong enough to charge alnico magnets, provided that the neo magnet is large enough (in total volume) and the magnetic circuit is reasonably good. An oversize neo makes up for many sins.

[kayakerca]

I use a pair of N42's - 3" X 1" X 1/2" in conjunction with a chain of ~ 15 smaller Neo's for individual Alnico magnet adjustment. Below is my jig for Strat style single coils. I put the bobbins in between the brass retainer spacers and put what ever size wood spacer between the 2 large N42 holders and slide them up to the bobbin. No problem fully charging the Alnicos with this jig. The size of the wooden spacer depends on what guass level I am looking for and whether to charge up the bottom or top of the Alnico's relatively stronger, weaker or the same. Next I grab the handles of the magnet holders and run them straight in and out from the bobbin, perfectly in alignment with the Alnico pieces. After thatI use the charge adjustment jig to deal with adjusting the gauss level on individual Alnico posts. I remove or add magnets as required (and as often as not, start from scratch again when I mess it up)





I always wonder whether sliding the bobbin between 2 dish magnets changes the orientation of the charge in the Alnico's as it leaves the charging area and the N42's (or whatever) are now pulling more at the side of the Alnicos than the ends. I asked one of the Magnet distributors if they thought it would change the polarity alignment at all and they told me they had no idea.

[Joe Gwinn]

I always wonder whether sliding the bobbin between 2 dish magnets changes the orientation of the charge in the Alnico's as it leaves the charging area and the N42's (or whatever) are now pulling more at the side of the Alnicos than the ends. I asked one of the Magnet distributors if they thought it would change the polarity alignment at all and they told me they had no idea.

If it's an oriented alnico, probably no effect aside from some weakening.

If unoriented alnico, one can get crooked magnetization. Sounds terrible, but probably not that much of a problem in practice.

[David Schwab]

I charge them like this:



Now I use two slightly longer magnets on each side.