"Donuts" around magnets in vintage Fender pickups

[Antoon]

Hi there!

Is there perhaps someone around here that could answer this? On older pre-1980 Fender single coils you often see these 'rings' or donuts as I like to call them, in the flatwork around the magnets. This picture of a '68 Telecaster bridge pickup shows what I mean:



These donuts appear either on the top of the pickup (e.g. the picture above) or on the bottom (e.g. old Tele neck pickups) but never simultaneously on top or bottom. They are there only on one side of the pickup, the side where the magnets are sticking out. On the other side where the magnets are totally flush with the bobbin they are absent. They must be some kind of tool mark and it came out like that from the factory. E.g. when Fender changed from flush to staggered magnets on Tele bridge PUs in '55 or so, you see the donuts flipping sides. First they were on the bottom and afterwards they appeared on the top

On some of the SD Antiquity PUs you can see the same thing but I never noticed any other PU manufacturer doing this. For fun I tried to replicate these tool marks but I couldn't. I tried undersized holes in the flatwork or no holes at all, as well as a a piece of metal with an oversized hole where the magnet comes out but all to no avail. Has anyone any idea how Fender did this?

[copperheadroads]

What material is the donut ? Fiber ?
is it the fiber being pushed up when the top of the bobbin was pushed on

[Chuck H]

It may just be the side effect of a dull tool. Hardened steel stamps are expensive to buy. You can be sure Fender didn't under use them before replacing the cutters for the sake of a clean hole that would never be seen. More likely they replaced the cutters when they couldn't get the magnets through anymore. Either the dull cutter itself caused the bilge or forcing the magnets through the slightly smaller hole made by the worn tool caused it. More likely the latter considering the way you've noticed it manifest.

[Lyrebird Steve]

forcing the magnets through the slightly smaller hole

I think this ... but it may also be slightly over dimension magnets .

However, if you install magnets by hand like this ...

... if the tool has a larger hole than both the magnet and the bobbin, this is what will result

[David King]

I'm going with the stamping die hypothesis. It almost looks like they purposely relieved the edge of the holes on the die for a consistent effect. Perhaps they mistakenly set up the press with an older .196" die and a newer .1875 punch?

[Chuck H]

I'm going with the stamping die hypothesis. It almost looks like they purposely relieved the edge of the stamp. Perhaps they mistakenly set up the press with an older .196" die and a newer .1875 punch?

See, now I didn't know there were two different sizes used! That creates a couple of other possibilities. The only sure thing is that nothing was tossed out just because it was "a little off" Leo would have found that unthinkable.

[jonson]

Undersized holes and beveled magnets or larger beveled magnets in 187 holes. The bottom doesn't flare out because with no bevel it cuts the forbon away and leaves it clean.

[David King]

Hmm I don't see much of a bevel on those magnets, maybe a little tumbling and some pick-wear? That said, whatever they used to hold the forbon flat while they pushed the magnets through could easily have had a little extra clearance.
I don't think they were still using any .195 magnets in the late 60's but I really don't know the dates of any of the Fender changes. Maybe Leo found an old box of fatties and wanted to use them up before he left for good.

[Antoon]

All these things have crossed my mind as well at some point but I still believe it is the result of a specific bobbin manufacturing technique that I don't know about. Not some coincidential side effect. The donuts are there on almost every Fender pickup from 1951 to well in the 1970s, consistently either on top or on the bottom. No matter what the magnet diameter or the amount of bevelling is (maybe they are a little more pronounced with the later unbevelled magnets). It must have something to do with the fact that the magnets are sticking out of the bobbin on that particular side. On the side with the flush magnets there are never there. Currently my best guess is the combination of a undersized magnet hole in the bobbin and an oversized hole in the steel dye on the other side of the bobbin but I think there is more to it than that.

[David King]

Antoon, (Welcome by the way!)
I've never seen one of these pickups in person so I shouldn't comment but it did occur to me that they may have been trying to deal with bobbins flaring and they figured that a tighter fit and a little extra fillet around the magnets might help stabilize the armature. Maybe they just thought it looked cool?
Has anyone ever seen it on the inside bottom flatwork towards the coil after cutting away the wire for a rewind? That would tell us something about how the bobbins were assembled.

[SonnyW]

All these things have crossed my mind as well at some point but I still believe it is the result of a specific bobbin manufacturing technique that I don't know about. Not some coincidential side effect. The donuts are there on almost every Fender pickup from 1951 to well in the 1970s, consistently either on top or on the bottom. No matter what the magnet diameter or the amount of bevelling is (maybe they are a little more pronounced with the later unbevelled magnets). It must have something to do with the fact that the magnets are sticking out of the bobbin on that particular side. On the side with the flush magnets there are never there. Currently my best guess is the combination of a undersized magnet hole in the bobbin and an oversized hole in the steel dye on the other side of the bobbin but I think there is more to it than that.

I get a little bit of that effect sometimes. It isn't as pronounced as those in the photo, but there is a trace of it, and there would be more if I didn't work to avoid it. I use an arbor press to install my magnets and I use a pair of sockets (5.5 and 5 mm) in sequence as a pressing tool. I hold the socket in place on the ram of my press with a neo magnet. I think the donuts may have been caused by a fair amount of space between the hole in the pressing die used to install the magnets and the diameter of the rod magnets if that makes any sense.

Here is the process I use and it is extremely fast. To install the rod magnets in the base forbon, I just hold them in place on the ram with the neo magnet. It stays stuck on the ram of my arbor press all the time. I put the beveled end of the uncharged rod magnet up to the ram and the neo magnet holds it perpendicular so I can press the rods into the forbon base. The rods don't have to be beveled on the end that goes into the base. When I get all of the rods installed in the base I put my spacer blocks on with a rubber band and place the top forbon over it. Then I stick a 5.5 mm socket onto the ram of my press and use that to start the top forbon over the beveled ends of the rods. (It also works if they aren't beveled, but it is easier if they are.) I just get them barely started one at a time. As soon as most of them are started I switch to a 5 mm socket, which fits much closer, and press the top all the way down to the spacers. The reason I start with the larger socket is because it is not too easy to get the hole exactly centered over the rods. But once they protrude through a little bit then I can switch to a socket that fits them closer. I think that if I didn't switch to a smaller socket I would see a lot more of the donut effect. I noticed it at first and that's why I use two sockets. But in a factory setting Fender probably would have made a die to do this and it would probably be fixed with only be one size hole, or maybe even have all six holes. But I would guess that they made the hole(s) in the die large enough to center easily over the rods and that's how the donuts got there. Just my idea on it.

[Joe Gwinn]

...

Where are you in the World? I helps us to know the context, to better answer questions. Please update your User Profile to give your country and city.

[big_teee]

I think Steves Reasoning in post #4, is the most logical.
Anyway IMO it is nondesirable and something we all try to prevent, when we seat our magnets.
T

[rhgwynn]

I get at least a little bit of "donuting" with nearly every pickup. It happens more with beveled magnets, because the non-beveled ones cut through the flatwork rather then displacing it. I usually shave the bulge off with an x-acto knife though so everything is flat and even, and the covers don't sit a little weird.

[big_teee]

Not Vintage, but if you want no donut pucker, try this.
Use .187 magnets, and .195 flatwork.
I glue all my magnets with CA, no lacquer dipping.
You can push them in with your fingers.
Glue the bottom magnets first, let dry.
Adjust the height on the top flatwork, and then glue the top flatwork.
Works slick!
T