Who Re-Magnetizes Magnets?

[DobieK]

I have a pile of magnets that I have pulled out of pickups over the years. They are stuck together in a clump, with screws and washers stuck to them. They have been rattling around in a drawer or boxes for quite a while.

I tried an old AV magnet from a Duncan P-90 in a Custom Custom and it sounded pretty weak. I grabbed another '59 mag from a defunct pickup and it is stronger, but I'm not sure the pup is full strength.

So, who can recharge these magnets and maybe tell me if some of them are alnico II or V?

I called a local place quite some time ago, can't remember who or what their business was, I just remember the cost they quoted me was prohibitively expensive.

 

[Gearjoneser]

Re: Who Re-Magnetizes Magnets?

I wonder if this would work?

On some apartments, there's an ultra strong electromagnet which you can shutoff by turning a key or pushing a button. It's replaced many standard door latches.
I should try putting a magnet up to that for half an hour. I just need a way to test the gauss level before and after.

 

[hanumanlangur]

Re: Who Re-Magnetizes Magnets?

For recharging magnets, it's just the reverse of degaussing them (Zhangliqun's method). You can check the link in my sig for details on how to do it. It's very easy and cheap. I've done it many times.

As for determining what type of magnet they are, I'm not sure how to do that. Maybe someone else has a method?

 

[uOpt]

Re: Who Re-Magnetizes Magnets?

I de-charged and re-charged with a pair of neodymium disks from Ebay and I measure the strength with a compass.

How many are we talking about? I might be willing to do it for you if you allow me to test these real quick with a pickup. Might be interesting to map how much charge gets what sound.

 

[PoorMan]

Re: Who Re-Magnetizes Magnets?

As for determining what type of magnet they are, I'm not sure how to do that. Maybe someone else has a method?

Cermaics and Alnicos look different, but pretty much all alnicos look alike. You could charge them and measure the gauss to make an educated guess.

Just buy some neodymium mags from Stewmac and you can recharge them yourself...cheap.

 

[uOpt]

Re: Who Re-Magnetizes Magnets?

Cermaics and Alnicos look different, but pretty much all alnicos look alike. You could charge them and measure the gauss to make an educated guess.

No, A2 and A5 have almost the same absolute strength. My measurements of a number of A2s and A5s are all intermixed.

 

[idsnowdog]

Re: Who Re-Magnetizes Magnets?

I had a PJ Marx pickup that was demagnetized and I charged it up between two spare speakers I had lying around. I put the pickup in the middle and lined up the polarity.

 

[PoorMan]

Re: Who Re-Magnetizes Magnets?

No, A2 and A5 have almost the same absolute strength. My measurements of a number of A2s and A5s are all intermixed.

Are you referring to your compass measurements? You can't measure gauss with a compass--you need a gaussmeter.

Fully charged Alnico 2 gauss is about 7,500
Fully charged Alnico 5 gauss is about 12,000

So yes, it can help you determine the type of mag.

 

[uOpt]

Re: Who Re-Magnetizes Magnets?

Care to explain why you can't measure magnet strength by measuring the pull on another magnet?

Sure you can.

 

[DobieK]

Re: Who Re-Magnetizes Magnets?

Not exactly what some folks suggested, but I picked up a strong magnet at the hardware store on the way home. I think it is ceramic. I have the pickup mag stuck to it. First north, then south, for about 20 minutes each. I'll pop it in the pickup and see how it works. I know it sounded weak last night.

I wish I had a gauss meter.

 

[PoorMan]

Re: Who Re-Magnetizes Magnets?

Care to explain why you can't measure magnet strength by measuring the pull on another magnet?

Sure you can.

You can measure mag strength (very roughly) that way. But you are mistaking gauss for mag strength. Mag strength is the product of gauss and oerstads.

The method I was talking about isolates the gauss. That is what can give you an indication as to what kind of mag you have.

Dobiek, (This might interest you too uOpt) you can build your own gaussmeter cheap...I don't have the link handy, but try a google search.

Also...pretty much any bike or speedometer repair shop can remagnetize them for you.

 

[uOpt]

Re: Who Re-Magnetizes Magnets?

You can measure mag strength (very roughly) that way. But you are mistaking gauss for mag strength. Mag strength is the product of gauss and oerstads.

Okay, but next time don't tell me I'm not measuring what I'm measuring. I wanted to measure the strength in one direction (the strings' direction) and that's what I did.

I wonder why the gauss rating should be so uniform when the strength varies so much? I highly doubt that all mixes of A2 and A5 we've seen fit those two numbers.

Having said that, time to get a gaussmeter.

 

[PoorMan]

Re: Who Re-Magnetizes Magnets?

I wonder why the gauss rating should be so uniform when the strength varies so much? I highly doubt that all mixes of A2 and A5 we've seen fit those two numbers.

An A8 is a good example of the influence of oersteds. (I'm operating off memory here) but IIRC A8s have less gauss than an A5, but an A8 is a more powerful magnet because it has much higher oersteds than an A5.

But it's not exact (there is some variance) and the gauss figure I gave (particularly for an A5 of about 12,500) is immediately after full charge...an A5usually won't hold that much guass.

 

[mattstratocaster]

Re: Who Re-Magnetizes Magnets?

i can remagnetize pickup magnets. I do it all the time for my projects. If you still need them done just let me know. I can do it for cheep to cover shipping back to you.

 

[DobieK]

Re: Who Re-Magnetizes Magnets?

i can remagnetize pickup magnets. I do it all the time for my projects. If you still need them done just let me know. I can do it for cheep to cover shipping back to you.

Cool, because I give up! Shoot me an email and let me know how much you would charge (no pun intended) to do 5 magnets. I'm getting nowhere finding a place that will do it locally.

algreenqa@yahoo.com

Thanks!

 

[Zhangliqun]

Re: Who Re-Magnetizes Magnets?

Care to explain why you can't measure magnet strength by measuring the pull on another magnet?

Sure you can.

A much better and simpler way is the ol' fridge test. Fully charge (or at least pretty close) the two mags and see which one is harder to pull off the fridge or an iron weight or any hunk of steel with a flat surface. The A5 will be very noticeably harder to pull off than the A2.

As for telling A2, A3, and A4 apart, it's durn near impossible because they're right there in the same strength range. A3 is supposed to look a little different because it has no cobalt, but these eyes can't tell.