demagnetized

[jason lollar]

believe it or dont, get a gaussmeter and see for yourself.

[solderstain]

Thanks for the tip, Jason, but I have one already.

[jason lollar]

well I see it, as soon as you put them in a brick youll loose some magnetism.
You may get different results.

[Possum]

hijacking the thread :-)

So whats the "magic" in the old PAF magnets? I have some theories, the old magnets were cast individually, sand cast, they were more porous, they were rough textured. Is it the porosotiy (tiny air pockets inside the mass) thats doing something strange, is it the rough texture of the bar, is there something strange about the content of the alloy? Kryptonite maybe? Opinions? Dave

[solderstain]

well I see it, as soon as you put them in a brick youll loose some magnetism.
You may get different results.

No question about that. But it's not because they're all together in the brick. I had typed all of this up before but decided not to overload my initial post here. (That'll teach me... now I'm typing it up again anyway. LOL!)

I've been working on a project with Wolfe and Robb Parr at All Star. It's no secret that when you pull a magnet off a brick and measure it, it will be at a lower strength than it was when it was originally charged. Robb mentions that Alnico-II magnets are more susceptible to this than higher grades. So I agreed to do a little testing so we could get an idea of how much of the charge is lost when pulling a magnet off a brick.

Through Wolfe, Robb sent me 100 brand-new Alnico-II magnets in two bricks of 50. I numbered them so I could keep track of them. Created a spread sheet to track the stages of the test... the whole nine yards.

Keeping in mind that I'm saying that you need relative motion between two magnetic fields in order to transfer charge (which is what's actually happening - it doesn't just disappear), I set my test up to compare what happens to the charge of magnet when you remove a magnet from the brick by sliding it off the brick, and by snapping it up on edge and lifting it straight off without sliding it off in direct contact with the magnet it was just snuggling with.

On one batch, I'd remove a magnet by sliding it off the brick. I'd measure it at six points - the center of each pole and 1/16" in from the end of each pole. To simplify the comparison, I averaged the three readings on each pole and recorded all of that in a spreadsheet. I'd set that aside, and take the next one off the brick... and so on and so on. I kept each magnet at least 2" away from the next one on a work table. When all 50 had been measured and recorded, I'd put the brick back together in the same order and manner (sliding) as I took it apart. Then I left it sit for 24 hours.

On the other brick, I removed the magnets by snapping each magnet up on end and lifting it off the brick with the absolute minimum sliding I could possibly manange. All the rest of the measuring and record-keeping was the same.

Then I did it again to each brick.

And again.

And again.

Five times per brick.

The results?

To no one's surprise, the magnets that I removed/added to the brick by sliding the magnets together suffered a very noticeable charge loss in the first one or two cycles... and then settled down pretty much. The final two or three cycles still showed a charge transfer, but there were some magnets that GOT STRONGER, because they were receiving charge from the magnet next to it.

The magnets that I removed/added to the brick by avoiding sliding the magnets together held their charge MUCH better than those that were rubbed together.

So what's my point? Well, Jason, yes - I agree that putting a magnet on a brick and then taking it off the brick will alter the reading you get on a Gauss meter. No question. But I say it's because there has been relative motion between the two - in the act putting the magnets together and taking them apart.

And HOW you put them together and take them apart will have a direct impact on HOW MUCH. How many times you take them apart and put them together will also have a direct impact.

But I stick by my stand that just having two STATIONARY magnets in proximity to each other won't charge one and discharge the other. There needs to be relative movement between the magnetic fields. Which gets accomplished by assembling the brick and taking it apart again.

Wolfe and I are working on a project that requires magnets of a very specific profile, and the neck pickup requires a different strength than the bridge pickup. I'll take a magnet off the brick by the 'snap and lift' method, measure it, and if it meets my criteria, I put the magnet directly into this piece of foam - to keep them from rubbing against each other and messing things up. Then I send it all off to Wolfe for the pickup model he's using them for. Fanatic? Maybe. But we have to be a bit whacko to be on these forums in the first place, I think...

[solderstain]

So whats the "magic" in the old PAF magnets? I have some theories, the old magnets were cast individually, sand cast, they were more porous, they were rough textured. Is it the porosotiy (tiny air pockets inside the mass) thats doing something strange, is it the rough texture of the bar, is there something strange about the content of the alloy? Kryptonite maybe? Opinions? Dave

I've only measured about 20 or so old '50s Gibson magnets, so I probably don't have as much of a basis as others here, but I can say that I don't think there's anything magic about the old PAF magnets. They vary as much as modern magnets do. There are plenty of people who will tell you that they've tried putting an old PAF magnet into a modern pickup and, or even just a different PAF - the results aren't always 'good'.

I think the magic of the old PAFs was the convergence of the pickup assembler grabbing one particular adjustable bobbin out of one bin, one particular slug bobbin out of another bin, and the next magnet off the brick...

and all three of those things just happened to match up in just such a way that you get a magic pickup. Not all PAFs are magic.

At the risk of taking the science out of it, I think the best ones were just a lucky draw of components.

Just my opinion, of course. I'm not a pickup winder (yet).

[Joe Gwinn]

But I stick by my stand that just having two STATIONARY magnets in proximity to each other won't charge one and discharge the other. There needs to be relative movement between the magnetic fields.

I don't think this is completely true. Two magnets forced together, with like poles close together, will demagnetize each other, no matter how carefully one pushes them together. How much the magnets will demagnetize each other will depend on the material or materials from which they are made.

The key is how much repulsive force the magnets develop. The higher the repulsion, the greater the demagnetizing effect, the better the magnet material must be.

[BobW]

Dumb question about weak magnets

I have a weak magnet in a pickup (jaguar) can I assume that simply placing a stronger magnet (neo) on the bottom of the pickup will help increase the weak field? I know absolutely nothing about the magnet structure of this pickup, but do know ohmic measurements indicate the windings are intact.

[Just Bob]

But I stick by my stand that just having two STATIONARY magnets in proximity to each other won't charge one and discharge the other. There needs to be relative movement between the magnetic fields. Which gets accomplished by assembling the brick and taking it apart again.

Temperature changes do it too. Even if there is no relative physical motion. Cycle the temperature up and down and the magnet strengths will change. Over the course of a couple decades I think that has a substantial effect. You don't need to get anywhere near the curie point. Just cycle it up and down the 30 or 50 degrees you get from the truck to the stage. Do that a thousand times.

[jason lollar]

So what's my point? Well, Jason, yes - I agree that putting a magnet on a brick and then taking it off the brick will alter the reading you get on a Gauss meter. No question. But I say it's because there has been relative motion between the two - in the act putting the magnets together and taking them apart.

Well the results are the same arent they? Its just how you want to talk about it IMO its moot

Wolfe and I are working on a project that requires magnets of a very specific profile, and the neck pickup requires a different strength than the bridge pickup. I'll take a magnet off the brick by the 'snap and lift' method, measure it, and if it meets my criteria, I put the magnet directly into this piece of foam - to keep them from rubbing against each other and messing things up.

Thats what I do although I store them differently.

Putting a weak A2 or A5 against a stronger one will charge it up a little.
Not sliding the magnets against each other is in my book, the proper way is to snap and lift.
however it could also be the proximity of north and south in the brick that degausses.

[Spence]

Alnico magnets do lose charge when in a 'brick'. Even a fully charged magnet will lose some charge in isolation. That's just the way it is.
personally, when I make a set of pickups I use the magnets as they come out of the box, only charging up the bridge pickup.
It's cheaper to buy magnets unmagnetized anyway so why not do that and then just charge them up yourself.

[NightWinder]

So, when you take the magnets of the brick, and say line them up side to side (N/S,attracting eachother with a 2 inch gap between them) and put them on the fridge, why does it seem that they are stronger when you first put them on the fridge, you litterally have to slide them to the edge to get a grip under them to pull them off,,,,,,but say 2 days later, you can remove them with your fingers without having to push them to the edge to get a grip under them. There is a noticeable difference a few days later. I just swapped out a magnet from another pickup and was surprised at how little pull there was compared to ones on the fridge? I know they stableize some in the pickup, but this is really noticeable strenght differences. HUmmm

[David Schwab]

Glad I mostly use ceramics....

[Possum]

hmmm.....

There's something in your research that you are missing, well maybe. Magnets charged in a brick are all charged at the same time, they don't all receive the SAME charge. This is most noticeable in alnico rod magnets charged in bricks, you can see differences in gauss readings that vary widely. Probably the same for bar magnets though I haven't really looked at that one much since I always charge them full then degauss to whatever levels I want. To make your experiment more relialbe you should individually charge each magnet then put them together in a brick. Probably get the same results though.

Also what is happening with the sliding off of magnets from a brick is yes you are degaussing them down to base level or slightly below. When you put them back in the brick you are basically recharging them because you are exposing them to a higher force. I recently had an experience with this. I had a customer request that the bridge be charged the highest and then progressively lower with the neck pickup being charged the lowest. He is paying me to design some pickups for him he wants to patent, so this set came back for some tweaking. I always ship my strat sets with pickups put together with magnets attracting to protect them against degaussing from uknown factors at the post office. The pickups that came back were all charged equally. What had happened was as a unit of 3 pickups together they had equalled out, recharged the weaker magnets and all returned to a higher charge :-) Lesson learned :-)

I agree with you, this "magic" PAF magnet thing I am pretty sure now is a myth. I recently got some alnico 5 magnets individually sand cast in a magnet manufacturer's lab. In other words made the "old" way. I am told these days bar alnico is cast in a brick then individual magnets are sliced out. This alnico magnet I have isn't any different sounding than modern alnico. It is slightly brighter due to its porosity is all.

I think the PAF magic is due to a synergy of components, the magnet wire had thicker insulation, the magnets slightly brighter due to porosity, the alloys used in the magnetic circuit, slightly taller coil bobbins than what we can get today. In fact most if not all of these parts are not available from suppliers made to the same specs and tolerances that were used in PAFs, you have to have them made if you want to duplicate that recipe.

[solderstain]

There's something in your research that you are missing, well maybe.

I'm not going to leave the whole quote here...

We don't know that all magnets these days are magnetized in the brick form. And we don't know that everyone does it the same. (Or do we?) And it really doesn't matter. To me the reason for individual magnets not charging the same, given similar exposure in the charger, is that they're not all exactly the same, metalurgically. I'd bet that no one really thinks that every single Alnico magnet that passes through their hands has had a perfectly-formulated metalurgical mix through and through. Those of you that own Gauss meters, I'm sure you've measured the north/south poles of a pickup magnet at more than one point on the pole - I've had a few magnets that vary in strength by as much as 50% from one end to the other. Given how carefully I practice taking magnets off the brick, why would any magnet vary like that? The metalurgical mix isn't always consistent. Imagine what the string balance sounds like for that pickup if you install that particular magnet... especially if you put that pole on the slug bobbin... The point is that I doubt that any given magnet is stronger or weaker because it was charged individually or in a brick. I think any given magnet is stronger or weaker because of the make-up of the metal itself. Just my opinion.

There's no reason for me to do any more research. The point of me doing the research I did do was so that we'd know how to deal with the magnets we're already buying. How best to take them off the brick; how best to ship them (being that I'm doing the magnet selection for Wolfe on this project... he doesn't have time for that and I do), and just how many times can you put magnets together and take them apart before they're a shadow of their former self. We know that now... research over.

And I guess people will believe whatever they want to about a magnet changing strength as a result of its proximity to another magnet. I didn't type all of this in an attempt to change anyone's mind. (I know I'm new here, and as such, have no credibility in this crowd.) Well before I knew what a pickup magnet even was (meaning back in Electric Shop in Junior High School), I was taught that adding or reducing magnetic charge happens with relative motion, not with simple proximity. I believe that. My point in posting all of this was to present a different view point. Sure stimulated some conversation, no? The biggest thing I learned was to take a magnet off a brick ONCE, and snap it off; don't slide it off. Changing the proximity of magnets changes their charge. That the magnitude of the change is affected by HOW you move the magnets in relation to each other tells me THAT'S what's doing it.

But heck - I'm a nobody.