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Post by EmRR on Mar 14, 2017 9:06:51 GMT -6
Electro-Voice shock mount pieces, 50-60 year old rubber parts. Still very pliable, starting to tear at the encased metal ring. I need to shore these up before they tear off completely, curious what the best rubber repair method might be for a part like this that lives under tension.  |
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Post by dandeurloo on Mar 14, 2017 9:35:03 GMT -6
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Post by EmRR on Mar 14, 2017 10:01:00 GMT -6
Yeah, something like that. Maybe a combo like that with a layover patch kit on top. Definitely don't want to blow it with the wrong approach.
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Post by johneppstein on Mar 14, 2017 13:50:55 GMT -6
This may be obvious, but have you checked with EV about replacements?
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Post by EmRR on Mar 14, 2017 14:16:12 GMT -6
99.9% certain they haven't provided replacements in many years. They barely seem able to provide parts for current mics. These shock mounts are fairly tough to find, and many times missing these rings when you do find them.
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Post by johneppstein on Mar 14, 2017 14:22:30 GMT -6
Epoxies tend to be on the rigid side, probably not a good choice. None of the JB Weld products on their "rubber" page are epoxies - most are silicone rubber, like an industrial strength bathtub caulk. One is a cyanoacrylic super glue. I'd try writing to their customer support for advice. |
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Post by EmRR on Mar 15, 2017 7:14:41 GMT -6
Someone recommended E6000, someone else recommended a Loctite product, both look promising.
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Post by svart on Mar 15, 2017 12:00:04 GMT -6
I'd second E6000, or some other "Shoe goo" product meant for repairing shoe soles. E6000 in such thin applications should remain very flexible. I also have used a squeeze tube of gutter sealant that was relatively sticky but thin enough to remain flexible. I got it at Lowe's. I've also used some specialty glues from 3M. They are much more rare, harder to use, and potentially expensive, but ultimately they could potentially have a perfect product available. EDIT: Like this one.. www.amazon.com/dp/B005TP50DI?tag=price1318-20&ascsubtag=230278318 |
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Post by johneppstein on Mar 16, 2017 1:41:58 GMT -6
Well, I know a fair amount about some adhesives, but I have no specific suggestion, positive or negative, in this case.
I do, however, have a bit of general advice to advance, for whatever it's worth -
A lot of the various adhesives suggested here are formulated as gasket materials as at least one application. Gasket materials are made to function under compression, while resisting blowout or leakage from lateral pressure. However the primary requirement of this application is resisting failure from shearing or breaking under tension, which is a quite different application of force. The adhesive needs to resist failure of the bond to the surface of the material and failure of the adhesive itself, which are not always the same thing. (This is not saying that one of these might not be suitable however...)
Another adhesive that was suggested was a cyanoacrylate super glue. Cyanoacrylates are known for extremely high tensile strength, but at the cost of very low shear strength. You can try to pull a super glue joint apart all day and it won't give but just a little sideways tap can be enough to completely shatter the bond. (I have a story about this concerning a drum roadie, a truck cab roof, a 6 pack of empty beer cans, a tube of superglue, and said roadie's teeth....)(Don probably knows who I'm talking about....)
Anyway, what I'm getting at is that you need to get the advanced product applications sheets and carefully research the failure modes of both the material and the bond to the other material. Also try to find out what the particular type of rubber was used for the shock mount - not all adhesives bond well to all rubbers.
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Post by EmRR on Mar 16, 2017 7:24:46 GMT -6
johneppstein, you are reading my mind, particularly the last part questioning the exact type of rubber this is. I don't think the EV info talks about it, but I'll circle back. "Rubber types in use 1955-1970" would be a useful resource.
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Post by svart on Mar 16, 2017 11:45:54 GMT -6
johneppstein, you are reading my mind, particularly the last part questioning the exact type of rubber this is. I don't think the EV info talks about it, but I'll circle back. "Rubber types in use 1955-1970" would be a useful resource. The 3M stuff I linked is a rubber adhesive. "This adhesive bonds neoprene, reclaimed, nitrile rubber (BUNA), SBR and butyl rubbers to metal, wood and numerous plastics." Seems to cover most types of castable rubbers and apparently has a heat-cure option to make a stronger bond, which you might need in your application. |
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Post by johneppstein on Mar 16, 2017 13:10:37 GMT -6
johneppstein, you are reading my mind, particularly the last part questioning the exact type of rubber this is. I don't think the EV info talks about it, but I'll circle back. "Rubber types in use 1955-1970" would be a useful resource. The 3M stuff I linked is a rubber adhesive. "This adhesive bonds neoprene, reclaimed, nitrile rubber (BUNA), SBR and butyl rubbers to metal, wood and numerous plastics." Seems to cover most types of castable rubbers and apparently has a heat-cure option to make a stronger bond, which you might need in your application. 3M is great. They make a rather bewildering array of targeted use adhesives, bound to be just the right thing for any application, if you can just figure out which. Fortunately they do publish excellent data and applications sheets; not all manufacturers do. One thing that might be of concern here is if the rubber is failing because it's actually starting to decay chemically, which could be a problem.... |
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Post by EmRR on Mar 16, 2017 13:12:23 GMT -6
Yeah, it's fairly pliable with no obvious decay yet, definitely time for a patch attempt first. These hold mics that have no other mounting options, so they have to be right.
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Post by EmRR on May 7, 2017 19:11:34 GMT -6
I gave E6000 a try, looked promising, but it stretched and tore under tension at the rubber tear, after which it all very easily peeled right back off the rubber. Back to the drawing board....
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Post by johneppstein on May 8, 2017 1:18:33 GMT -6
I gave E6000 a try, looked promising, but it stretched and tore under tension at the rubber tear, after which it all very easily peeled right back off the rubber. Back to the drawing board.... That what I was afraid of. I've had generally poor results using "Shoe Goo" type products to repair shoes, I was doubtful they work well under tension in an application like this. Have you tried that 3M product Svart suggested? That looks pretty promising. When I was a service tech we used a yellow 3M automotive weatherstripping glue to attach the rubber tips on Fender Rhodes pianos (as spece'd by the factory) but I don't know how well that would do under tension... |
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Post by keymod on May 8, 2017 4:47:21 GMT -6
Bicycle tire patch ?
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Post by EmRR on May 8, 2017 6:51:04 GMT -6
Haven't had a chance to try anything else yet, looking into next options. Bicycle tire patch pieces cut down to size may be a good option, also on the list to consider.
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Post by johneppstein on May 8, 2017 22:34:24 GMT -6
Haven't had a chance to try anything else yet, looking into next options. Bicycle tire patch pieces cut down to size may be a good option, also on the list to consider. Something else you might consider (although I have not tried it on this type of application) is the contact cement sold as Plio-Bond, which, as far as I've been able to determine, is the same cement supplied in the blank tube in JBL reconing kits. Make sure you shake it well before use, even if it comes in a tube. With any of these cements I'd suggest finding some scrap pieces of the same rubber formulation used in your shock mounts and perform some tests before comitting to anything for the repair. Some glues and cements can "poison" a glued surface such that other glues won't work if the joint fails. |
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Post by EmRR on May 9, 2017 5:40:38 GMT -6
Thanks John!
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Post by m03 on May 9, 2017 9:46:21 GMT -6
What model EV are these for?
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Post by svart on May 9, 2017 10:13:35 GMT -6
Haven't had a chance to try anything else yet, looking into next options. Bicycle tire patch pieces cut down to size may be a good option, also on the list to consider. Something else you might consider (although I have not tried it on this type of application) is the contact cement sold as Plio-Bond, which, as far as I've been able to determine, is the same cement supplied in the blank tube in JBL reconing kits. Make sure you shake it well before use, even if it comes in a tube. With any of these cements I'd suggest finding some scrap pieces of the same rubber formulation used in your shock mounts and perform some tests before comitting to anything for the repair. Some glues and cements can "poison" a glued surface such that other glues won't work if the joint fails. Silicone does that for urethane adhesives. |
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Post by rowmat on May 9, 2017 10:47:35 GMT -6
Maybe something like a windshield bonding adhesive could be suitable?
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Post by EmRR on May 9, 2017 18:24:37 GMT -6
What model EV are these for? 642 shotguns |
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Post by maq3396 on May 14, 2017 20:09:16 GMT -6
Hi Doug,
Was at a trade show last week and Loctite had a booth set up.
The woman running it had spent 20 years in the conveyor belt business and was very familiar with the repair of rubber products.
Seems loctite has released a new product for the repair of belts and thought it may work for you.
The glues required are different for natural vs synthetic rubbers-do you know which yours is?
She recommended the products on page 115 of their "The Adhesive Sourcebook" 2017 Vol 20
The product is PC7393 although PC7350 and MR5023 are also in this section.
I believe these are for natural rubber.
This book is 213 pages long with a huge number of products...suspect if you dropped them a line they could help.
If you cannot find the catalog online and would like it let me know and I will drop it in the mail for you.
Cheers
Mac
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Post by EmRR on May 15, 2017 7:27:36 GMT -6
Thanks Mac, I'll have a look. I do not know the type of rubber, all I do know is it dates to the late 1950's or early 1960's.
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