You went from great advice to this?
Time for a little materials research.
Neither silicone nor epoxy are compatible with PP.
You are not looking for flexibility where the lead passes through the cone. The leads do that in the free air between the cone and the terminal.
The manufacturer of the driver used PP hot glue.
Time for a little materials research.
Neither silicone nor epoxy are compatible with PP.
You are not looking for flexibility where the lead passes through the cone. The leads do that in the free air between the cone and the terminal.
The manufacturer of the driver used PP hot glue.
Yes, it did. I don't know why, though, as it happened before I got them. Does a single failure (and I've found no other reports of similar failures in the Usher S-520) justify the conclusion that the manufacturer picked the wrong type of adhesive? I'm not sure.
You suggest epoxy. I guess epoxies may be good for some cone materials, but I'm reading that epoxies generally aren't recommended for polypropylene. If you know of one which is, it would be good to hear.
But now that I've learned there are hot glues suitable for PP, thanks to @Cal Weldon, I'm going to go that route. I've ordered some of the Bosch sticks - that seems to be the only brand claiming PP compatibility that's readily available in the UK in small quantities. They'll take a few days to arrive but I'll post an update in due course.
Thanks again for all the suggestions - my admiration for diyaudio grows daily.
Edit: I looked again and found this thread reporting woofer lead problems on the S-520: https://www.diyaudio.com/community/threads/usher-s-520-woofer-midbass-problems.303628/
However those woofers are a bit different from mine - they have the lead-out wires routed across the spider, not up the back of the cone.
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Yes, it should be stressed that the issue has been resolved thanks to Cal's welcome late intervention in post #30.
However, I must say that I learned a lot during the earlier discussions about glue and how it bonds to a substrate.
I look forward to reports of a successful bonding in your case!
Let's face the (almost) obvious. It failed to do excess mechanical (physical) interference, not simple cone movement. Something tugged on the tinsel lead hard enough not only to dislodge the sealant but to break the connection to the VC wire. I think we can all admit to that mistake after this many years of 'speakering', or am I the only clumsy one out there?
I forgot...
See if you can get a small quantity of lamination adhesive, it is used in printing plants to laminate BOPP film to printed paper sheets for gloss/protection.
The normal pack here is 40 kilos, you can politely ask and get a large spoon or so of it.
Shelf life is maximum a week out of the container, it is about the consistency of honey, and white wood glue like in appearance.
BOPP = Biaxially Oriented Poly Propylene.
It is also a film used for adhesive tape, like box tape, the adhesive selection is vast....and not appropriate to discuss here.
Also used for printed packaging...like soap wrappers, it is a versatile material.
I would take a trial before doing the final repair, as the adhesives I have suggested do not behave like wood glue does.
You could add a small quantity of graphite powder to make it black, try it elsewhere first.
I personally would use a glue gun with the regular LDPE based stick, on to a clean surface, as in my experience LDPE and PP can be mixed together in any ratio without bonding problems.
I think that is the least complex solution.
See if you can get a small quantity of lamination adhesive, it is used in printing plants to laminate BOPP film to printed paper sheets for gloss/protection.
The normal pack here is 40 kilos, you can politely ask and get a large spoon or so of it.
Shelf life is maximum a week out of the container, it is about the consistency of honey, and white wood glue like in appearance.
BOPP = Biaxially Oriented Poly Propylene.
It is also a film used for adhesive tape, like box tape, the adhesive selection is vast....and not appropriate to discuss here.
Also used for printed packaging...like soap wrappers, it is a versatile material.
I would take a trial before doing the final repair, as the adhesives I have suggested do not behave like wood glue does.
You could add a small quantity of graphite powder to make it black, try it elsewhere first.
I personally would use a glue gun with the regular LDPE based stick, on to a clean surface, as in my experience LDPE and PP can be mixed together in any ratio without bonding problems.
I think that is the least complex solution.
In order to use superglue, the surface is first treated with heptane. It takes about a minute, as the plastic chains break and associate with the heptane. Which then leaves them hanging when it leaves. Looking for something to do.
There is just nothing to hang on to, if the chains are not broken. This isn't about accelerators such as acetone, it's a surface alteration. You shouldn't get it on other plastics though, as they can break up. Micro hazing is a nice keyway, but no use on nearby suspension components.
Not completely accurate, but touching a few bases, for those that know more.
If you can't get the glue gun in there, or figure how to melt it in situ, then a drip of superglue might make you wonder why you even tried.
'Superglue all plastics' is the two part kit for these types of plastic.
There are a few other options still, if adhesives fail you. Like sowing, or taking a longer tinsel over the spider. Keep faith 🙂
There is just nothing to hang on to, if the chains are not broken. This isn't about accelerators such as acetone, it's a surface alteration. You shouldn't get it on other plastics though, as they can break up. Micro hazing is a nice keyway, but no use on nearby suspension components.
Not completely accurate, but touching a few bases, for those that know more.
If you can't get the glue gun in there, or figure how to melt it in situ, then a drip of superglue might make you wonder why you even tried.
'Superglue all plastics' is the two part kit for these types of plastic.
There are a few other options still, if adhesives fail you. Like sowing, or taking a longer tinsel over the spider. Keep faith 🙂
Why not just use what the manufacturer used. Or perhaps what speaker repair outfits use, ie: The Speaker exchange, Simply Speakers, etc.?
Thanks for the suggestion. I see that this product is indeed recommended for PP. But it appears to be intended for bonding two close-fitting surfaces. Unfortunately that’s not really the situation here. What I need is a sizeable adhesive 'blob' that will adhere to the cone, but will also encapsulate the junction of the coil lead-out wire and tinsel lead. Hopefully the Bosch hot melt will work.
I'd like to. As Cal said above, its almost certain that the original glue is a form of hot melt designed for plastics like PP. I'm intending to use such a glue, as I've indicated above.
For laying up tinsel leads, I normally use rubber toughened thick CA glue and an accelerator and if its a pp cone, use a felt tip primer pen.
CA glues are used extensively these days in the manufacturing of speaker drivers.
https://www.gluespec.com/blog/cyanoacrylate-adhesives-in-loudspeaker-assembly
I see that the pp cone is clear, so it might not have any UV stabilisers added. So keep it covered with the grill and out of direct (and indirect) sunlight or else it might have a shortened lifespan.
Good luck with the hot melt.
CA glues are used extensively these days in the manufacturing of speaker drivers.
https://www.gluespec.com/blog/cyanoacrylate-adhesives-in-loudspeaker-assembly
I see that the pp cone is clear, so it might not have any UV stabilisers added. So keep it covered with the grill and out of direct (and indirect) sunlight or else it might have a shortened lifespan.
Good luck with the hot melt.
Repair outfits are able to buy quantity. Some products aren't available in small quantities. Also, the places you mention are in the US, Importing would put the costs up further for me.
Thanks. Any links for purchase, for future reference?
Superglue isn't good at bridging, but I have had no problems holding tinsel leads to woven cones. You can build it up with further applications to.
It's said you can cover the joint with a bit of plastic bag. It sets quickly. I have no experience of this though.
Hopefully you can get the hot glue in there, as it sounds like the more appropriate fix. I just wonder about about access.
It's said you can cover the joint with a bit of plastic bag. It sets quickly. I have no experience of this though.
Hopefully you can get the hot glue in there, as it sounds like the more appropriate fix. I just wonder about about access.
Be sure try on a shampoo bottle or something, before the cone. I have reservations about the close melting points, of basically the same material. The factory had no spider in the way, and perhaps no dust cap. The cone was likely on a former like it was made on. Capable of sinking away excess heat. It's only now I see the actual construction. Somehow I thought it reflective, not transparent. There is access for wet tissue beside the bullet. Trials on empty bottles will tell you a lot.
Edit: My oldest of irons takes a metal bar like tip. I might try a tube in it's place, with a core of glue inside. Position, and wait for the flow. Which would be sudden and total I imagine. As it melted from the hot end, down to the tip, then flowed above melting point.
Actually, most of my irons could have the tip extended with a sleeve, and I have hot knife attachments that might be better than a screwdriver
Edit: My oldest of irons takes a metal bar like tip. I might try a tube in it's place, with a core of glue inside. Position, and wait for the flow. Which would be sudden and total I imagine. As it melted from the hot end, down to the tip, then flowed above melting point.
Actually, most of my irons could have the tip extended with a sleeve, and I have hot knife attachments that might be better than a screwdriver
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Why not use what the manufacturer did unless you want to experiment and perhaps fail again?
The reason I suspect the glue was hot (other than it looks like it) is for one simple reason: cure time. When making 100’s or even 1000’s of cones at a time, I suspect that becomes a huge factor. If production stalls because you are waiting for the adhesive to dry, well…
Looking at the CA option that afa posted appears interesting and quick curing but that blob sure looks like what I have been promoting.
The reason I suspect the glue was hot (other than it looks like it) is for one simple reason: cure time. When making 100’s or even 1000’s of cones at a time, I suspect that becomes a huge factor. If production stalls because you are waiting for the adhesive to dry, well…
Looking at the CA option that afa posted appears interesting and quick curing but that blob sure looks like what I have been promoting.
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