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#402443 - 04/05/14 07:51 PM Fixing polyprolene driver (feedback needed)
chesseroo Offline
connoisseur

Registered: 05/13/02
Posts: 4829
Loc: western canada
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.

-------------------------------
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.

==================
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)
_________________________
"Those who preach the myths of audio are ignorant of truth."

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#402445 - 04/05/14 08:25 PM Re: Fixing polyprolene driver (feedback needed) [Re: chesseroo]
Socketman Offline
connoisseur

Registered: 07/12/09
Posts: 1190
Loc: Whitehorse YT
I have some polk speakers in my car that have a center like you describe. I used my hot glue gun with 3m yellow glue stick and it seems fine since I fixed it 2 years ago. My sub surround came delaminated from the main driver and I repaired it today using Lepage contact cement. With contact cement only a vey thin layer is required on each surface , I guess I will find out soon enough.

Drivers are designed to be a rigid as possible while remaining light weight. I would think there is less flex at the middle than at the outmost portion of the driver.
_________________________
DOG is GOD spelled backwards.
I blame my terseness on my keyboard. smile

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#402446 - 04/05/14 08:29 PM Re: Fixing polyprolene driver (feedback needed) [Re: chesseroo]
Serenity_Now Offline
local

Registered: 03/28/14
Posts: 211
Loc: PEI, Canada
Sorry, First glue was for porous cones... This one is for poly.

Prep area well first to remove all old glue. Test solvents first. Good luck. smile

http://www.parts-express.com/black-rubber-cement-speaker-repair-glue-1-oz-bottle--340-078


Edited by Serenity_Now (04/05/14 09:13 PM)

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#402447 - 04/05/14 09:32 PM Re: Fixing polyprolene driver (feedback needed) [Re: Socketman]
chesseroo Offline
connoisseur

Registered: 05/13/02
Posts: 4829
Loc: western canada
Originally Posted By: Socketman
I have some polk speakers in my car that have a center like you describe. I used my hot glue gun with 3m yellow glue stick and it seems fine since I fixed it 2 years ago.

This is interesting since most hot glue materials are meant for porous surfaces. Rarely would it stick to a plastic especially PP.
I would have to see more info on their yellow stick composition.

Quote:
My sub surround came delaminated from the main driver and I repaired it today using Lepage contact cement. With contact cement only a vey thin layer is required on each surface , I guess I will find out soon enough.

Material types are the key here. It is likely the surround is a rubber based material; very different from PP. I can see contact cement used in this instance for bonding these two materials.

Quote:
Drivers are designed to be a rigid as possible while remaining light weight. I would think there is less flex at the middle than at the outmost portion of the driver.

This was also my thinking and why a cyanoacrylate might work. Question is, for how long?
I don't want to repair again, not even in 10 years. There is another part to this story about a "t-nut" and the driver screws that can complicate things in regards to removing the driver for repair, without wanting another repair.
_________________________
"Those who preach the myths of audio are ignorant of truth."

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#402448 - 04/05/14 09:39 PM Re: Fixing polyprolene driver (feedback needed) [Re: Serenity_Now]
chesseroo Offline
connoisseur

Registered: 05/13/02
Posts: 4829
Loc: western canada
Originally Posted By: Serenity_Now
Sorry, First glue was for porous cones... This one is for poly.

Prep area well first to remove all old glue. Test solvents first. Good luck. smile

http://www.parts-express.com/black-rubber-cement-speaker-repair-glue-1-oz-bottle--340-078

LOL ya test solvents first indeed.
Although this is touted as a PP material, it could be a blend of mostly PP with something else for all i know.
If it is truly near pure PP, i'm not too concerned about the use of acetone, alcohols and some hydrocarbons (often used as solvents in most glues).

I'll see if i can find a MSDS on this material. Offhand i would say it also fits into the elastomer materials group. I'm glad to see it specifically states it is suitable for poly and speaker applications. A contender for sure!

As for Parts Express, they use UPS and have a not completely clear brokerage charge for Cdn shipments.
I don't trust UPS any further than i could throw the company.
_________________________
"Those who preach the myths of audio are ignorant of truth."

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#402473 - 04/06/14 03:18 PM Re: Fixing polyprolene driver (feedback needed) [Re: chesseroo]
Socketman Offline
connoisseur

Registered: 07/12/09
Posts: 1190
Loc: Whitehorse YT
The sub from my car that I fixed is also made of polypropylene and the contact cement seems to be holding up just fine. I think that prep is the most important part here. I used some 400 grit sand paper to rough up the surface and cleaned both surface with alcohol as well as a thorough hand washing. I know you want to fix and forget but realistically I don't see that happening. Since the original manufacturer could not get those results I don't suspect any layman can. Btw it was high strength hot glue from Stanley.

<a href="http://s75.photobucket.com/user/Socketman/media/PolkIntegraFront_zpsb78ed41f.jpg.html" target="_blank"><img src="http://i75.photobucket.com/albums/i319/Socketman/PolkIntegraFront_zpsb78ed41f.jpg" border="0" alt=" photo PolkIntegraFront_zpsb78ed41f.jpg"/></a>

Speaker I hot glued





How about this looks interesting.
_________________________
DOG is GOD spelled backwards.
I blame my terseness on my keyboard. smile

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#402556 - 04/07/14 04:30 PM Re: Fixing polyprolene driver (feedback needed) [Re: Socketman]
chesseroo Offline
connoisseur

Registered: 05/13/02
Posts: 4829
Loc: western canada
Originally Posted By: Socketman
Since the original manufacturer could not get those results I don't suspect any layman can.

A good point, although i don't think that a material created possibly decades ago is equivalent to newer formulations in the past 10 or 20 years in the adhesive industry. Even still, i could expect an eventual failure of that material after 10 or 20 years depending on the conditions. These speakers may have had occasional sun exposure (through windows) which i'm sure has accelerated the decay of the old resin.

Your speaker looks pretty good from the photo (you said that was 2 years ago?). Is that a pure PP cone or is it infused with material?
Just guessing by the 'honeycombed' look on it, i've seen similar drivers before and they were made of other fibers woven into the plastic.


Quote:
How about this looks interesting.

Yes it does actually but i would have to buy a glue gun.
The MSDS doesn't say much about the glue sticks other than having polymers and tackifiers.
http://www.gluegunsdirect.com/tecbond-263-12mm-polypropylene-glue-sticks?path=20_59_26

I think i'll look around for an elastomer type, maybe from the list i compiled previously and give that a go, once i can find a place that sells it.


Edited by chesseroo (04/07/14 04:31 PM)
_________________________
"Those who preach the myths of audio are ignorant of truth."

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#402578 - 04/07/14 05:38 PM Re: Fixing polyprolene driver (feedback needed) [Re: chesseroo]
Socketman Offline
connoisseur

Registered: 07/12/09
Posts: 1190
Loc: Whitehorse YT
Chess, the door speaker is a fiber woven composite , I forgot to mention that. My sub is PP , aka plastic grin Glue guns are like 15 bux , I am going to get some of those glue sticks for future emergencies. I have a set of HPM 900,s that used to have graphite cones, repaired a crack in them with 5 minute epoxy. Since they are now 35 yrs old I have replaced the cones since the surround rotted off and the drivers destroyed themselves. NE way keep us posted.

Richard
_________________________
DOG is GOD spelled backwards.
I blame my terseness on my keyboard. smile

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#402580 - 04/07/14 05:43 PM Re: Fixing polyprolene driver (feedback needed) [Re: chesseroo]
chesseroo Offline
connoisseur

Registered: 05/13/02
Posts: 4829
Loc: western canada
Thanks.

I'm looking through my list of Canadian electronics supplies stores for what they have for options. There is one here in town as well that i will contact.
_________________________
"Those who preach the myths of audio are ignorant of truth."

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#402624 - 04/07/14 08:05 PM Re: Fixing polyprolene driver (feedback needed) [Re: chesseroo]
Adrian Offline
axiomite

Registered: 12/27/08
Posts: 6613
Loc: It's all about the location.
Give Solen a call, maybe they can help you.
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Half of communication is listening. You can't listen with your mouth.

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