Cracks in the bobbins?

Mincer

Administrator
Staff member
I have only had this in one guitar, and it seems like there are more there than before. What causes this, and does anyone else have em?
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Re: Cracks in the bobbins?

Hasn't happend to any of my proper USA duncans, but a piece of the bobbin chipped off a duncan designed HB103 i have right by the edge of the low E slug. Fortunately it didn't destroy the coil when it came off, so I just used some basic white craft glue to glue it back carefully and wiped up the excess. That stuff dries clear so you can barely tell it was ever broken. Still works fine, but it's sitting in a box, unused.

I've actually not seen cracking like yours in pickups before
 
Re: Cracks in the bobbins?

Yeah, these are the only ones I have ever seen. Never happened on any of my others. They are an APH-1 and a CC. Strange.
 
Re: Cracks in the bobbins?

Someone that used to be with Duncan called them something like spider veins and tried to suggest they only happen with a certain % of pickups made. Meanwhile, a boutique dealer I know has not been thrilled with seeing them show up like this from their OEM, prompting them to consider other options. I don't think I've seen them on CS models, so I'm curious if it has something to do with the production floor process.


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Re: Cracks in the bobbins?

I have a CS hum bucker with a "spider vein" running between the poles. As log as the pickup doesn't break.
 
Re: Cracks in the bobbins?

I wonder if they look more severe in white pickups because of the higher visibility contrast.


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Re: Cracks in the bobbins?

Funny enough none of my old duncans have these. But I have a TB4 that came stock in a DK2 and its developed some but not nearly as serious the ones Mincer shows and I have a SH5 thats newer that I bought used that has one crack running from a screw to the edge.

No idea what causes it if I had my guess its something to do with the bobbin material, Maybe the older material was more flexible. I know some plastics the oil dries out in them and they shrink maybe its something similar to that also.
 
Re: Cracks in the bobbins?

There was a thread about it a few months back. Something about how the bobbins are made.

Curious to know if it has something to do with the bobbin material or the assembly process and if it has anything to do with a cost saving measure. As in, is saving $0.03 per bobbin (a fictional amount) worth people having a concern over construction quality?


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Re: Cracks in the bobbins?

*shrug* I'm not really aware of the stress parameters of the bobbin materials, and if physical and temperature stresses can cause those, but that really should not be a normal thing for new pickups. Even if it does happen as a result of the process a small % of the time, those items should be removed from the assembly line and scrapped instead of making it to consumers.
 
Re: Cracks in the bobbins?

Let's be clear, what you have in those photographs are indeed cracks. They've filled up with dirt and turned dark. Not a huge deal, the pickup is probably fine. If it's really new then maybe a warranty thing, but those are not the mold lines referred to as spider whatever. That's when the material flows into the mold, around the pins for the pole pieces, and reconnects between the poles. Your cracks go to the edge, and shoot off in different directions. "Spider whatevers" are typically limited to between the poles, following logical flow lines.
 
Re: Cracks in the bobbins?

Let's be clear, what you have in those photographs are indeed cracks. They've filled up with dirt and turned dark. Not a huge deal, the pickup is probably fine. If it's really new then maybe a warranty thing, but those are not the mold lines referred to as spider whatever. That's when the material flows into the mold, around the pins for the pole pieces, and reconnects between the poles. Your cracks go to the edge, and shoot off in different directions. "Spider whatevers" are typically limited to between the poles, following logical flow lines.


I'd see that on the bridge pickup.

what is in the neck really seems to fall in the category of the insect repellant... or whatever it's called...wouldn't you think?
 
Re: Cracks in the bobbins?

Both pickups are indeed fine. And yeah, those are cracks- including a pretty big one on the bridge pickup. All my other pickups are black, and I don't see cracks on them. It doesn't bother me here on the white ones really...as long as the pickup works. The main thing for me is really about prevention for other pickups. Are white ones more susceptible? I live in a fairly temperate, humid environment (Florida), so I don't know if it would be climate changes. Strange, huh?
 
Re: Cracks in the bobbins?

I have a couple of those, among others an old double cream DD. Looks really cool.

To me this looks like the plastic was missing elasticizer (sp?) and then got brittle and couldn't follow natural temperature related expansions and contractions.
 
Re: Cracks in the bobbins?

I guess I'd wonder how old they are too. You can tell it's the old logo so they're a couple years old at least? In my opinion it is possible that the color of the bobbin can influence how crack-prone it is. I only have anecdotal recollection of this, but it's possible. It's also possible that it has to do with a certain "batch", right? So one batch is different for some reason and is more prone, but that has nothing to do with whether buying a brand new white humbucker is more or less prone to cracking.

Cracks like that could eventually lead to a short IF the internal coil geometry shifts because of it. So if the coil core is fine and those are surface cracks, then nothing should change. But it's like an earthquake/tectonic plates. If they shift a little, the coil tension can relax and could theoretically change the sound or it could poke a short in the wire somewhere inside. I'm not saying this can happen to you, just saying if the pickup stopped working, and it was in the warranty period, I'm sure they'd replace it.
 
Re: Cracks in the bobbins?

These are at least 4 years old, so they certainly aren't under warranty. The goal in showing y'all this wasn't really about replacement. It was more about if white (or light colors) are more prone to cracking. I don't have this in my black bobbins, so my guess is that it is the plastic? Who knows, maybe at some point pieces will crack off, I don't know. But for right now, they work just fine, and I am not really concerned, unless this happens to all white bobbins, then there is a problem, I am guessing.
 
Re: Cracks in the bobbins?

Yeah, more of a cream coil thing I think.

img_8998__beaten-up-duncan-dd__lpc89_med.jpg
 
Re: Cracks in the bobbins?

Yeah, more of a cream coil thing I think.

img_8998__beaten-up-duncan-dd__lpc89_med.jpg


that one there looks beat to hell, no matter how you slice it.


I keep thinking about the idea from post #6 that is just wondering if the cracks are just more noticeable in the white bobbins because, well, they are white. the cracks in that one also appear more dominant in the slug coil, which was also asked about in one of the threads linked in post #10.
 
Re: Cracks in the bobbins?

I wonder if it is in the white plastic as I have encountered this in 2-3 pickups, all white or cream colored, all were different brands. I wonder if it is in the formulation
 
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