Well when in doubt, turn to the Axiom forums for both good technical responses and horrible puns. (I have none at the moment.)

Long story short, there are these speakers (brand, type irrelevant).
The drivers are polypropylene (PP).
The dust cap popped off and needs to be re-glued to the cone.
Now, the cap is not typical. It is concave AND it is mass loaded. As such, it performs a duty beyond just plugging over the hole.

Here is an example of what it would look like intact (and no, this is not the actual speaker).



Now picture a small epoxy puck mounted on the backside of the dust cap and you understand the mechanism.

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The question? (one that i have researched enough but would still like experienced opinions)

Which glue to use for the repair?

There are numerous choices to bond plastic to plastic (and in this case PP). Having researched posts from other forums as well, there seems to be no consensus but lots of opinions, some from those who claim to have done the repair, others giving what they "think" would work, and other who refute everyone of course.

The options?
  • Some type of cyanoacrylate (most commonly referred to as Crazy Glue; dries usually to a "brittle" but very hard bonded finish)
  • Elastomers/Plasticizers (dries but maintains an elasticity)
  • Contact glues (never dry)

Some examples (and pluses/minuses):

Cyanoacrylate: Home Depot stuff from Loctite
http://www.homedepot.com/p/Loctite-Plastics-Bonding-System-681925/100371829
It has been said not to use these because the glue when dry is not flexible. However, isn't that the point of the driver? To be non-flexible as much as possible?
But i can understand the idea of potential cracking and re-fixing again in the future. However there were report of success using this material.

Elastomers/Plasticizers
http://www.parts-express.com/5-minute-two-part-epoxy-adhesive-45-oz-kit--340-650
http://3m.hillas.com/pc-1553-1025-3m-4693h-scotch-grip-plastic-adhesive-clear-5-oz-tube.aspx
Clear silcone caulking (which i'm not going to use)
Not sure where i can get these in Canada. Am leaning towards this option as the 3M product was mentioned several times on other forums. The Parts Express material is a 2 stage process and uses Bisphenol A which is a very well known plasticizer (and can mimic human hormones; in the simplest terms) but would likely be effective for its purpose of maintaining flexibility (if that is the goal here).


Contact glues
I found several but i'm not going to use these. The product for fixing this needs to dry. A material that remains tacky, with a weighted dust cap, will dislodge over time. I'm fairly confident of that outcome.

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Anyone have an experienced opinion?

Any technical Axiom folk care to weigh in? (can send me a PM if there is any concern about posting publicly)
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"Those who preach the myths of audio are ignorant of truth."