I worked several years as an electronics manufacture engineer. its a fact hat a lot of ideas always comes from the end user, but also its is better to find a solution at the manufacturer facility, than at the final user.
may be if the audio wire is nylon stranded, the rubber will adhere to the nylon strands during the heat press process, that way making the audio cable and the boding with the rubber more durable. I have checked cost of cheap thin audio cable vs nylon stranded in china and is just couple of cents more
maybe, sand paper the vinyl insulation in contact with the rubber and add two more seconds of heat press
maybe making some king of knot at the end of the audio cable inside the coil
maybe a couple of drops of a heat activated potting or glue to the end of the audio cable before the heat press
maybe a combination of all the ideas…!
I completely agree with all of your Ideas, and they should work. Bonding the medical elastomer (TPR) to vinyl is a challenge, and I have requested test articles from the manufacturer for all of the above, and a few other things as well. The problem seems to be that the manufacturers of the molded plug inserts don’t seem to be able to do some of these things properly, and some of the things we have tried, such as braided nylon cladding actually slips around the cables and does not effect a permanent grab onto the vinyl surface.
The knot Idea is good. I know because I have spent many hours developing that solution too. The knot that I tested, and later specified, is what is called a constrictor knot. (I really have tried all that you have suggested, and much much more…) The factory in china was unable to correctly tie and tighten the knot, and ultimately declined to make further attempts. But a properly tied and tightened constrictor knot before overmolding the TPR will definitely work, if I can find someone on this planet who can follow the directions properly :\
For anyone who has never tried to manufacture something like this, you really would be surprised to find how hard it is to get things made correctly as they are designed.
So, this is an ongoing challenge.
a small tight wrap around the end of audio cable may work as the “knot”…
" if I can find someone on this planet who can follow the directions properly"
… that is a very, very hard specimen to find!
a friend of mine hire 15 to 20 new employees every week, he fire 15 to 20 employees every week!
he told me that’s the only way he was able to find 800 employees that follows 80% the instructions.
yes, that is about right unfortunately.
Culture differences and language problems. Loss of face may be why they decline to try again.
I have found in some cultures their English is so bad they only listen to keywords and they don’t really care enough to make sure everything is right until it’s possibly too late. Overworked and not checking details.
In China you will get products that look the same from several factories. They themselves buy the components, but they put them together very differently.
A red led bulb type I use is good. Identical looking bulbs get too hot.
I’m not surprised you have trouble getting the factory to do it right, Bob. You’re a very precise type of person. That doesn’t play well with oriental countries.
I have found if they say OK, OK, they aren’t even listening. They just want to get rid of you and will promise anything they don’t intend to keep to make you hang up the phone. They will say the customer requested delivery another day if they don’t want to keep delivering until done. Yep, I can vividly imagine the troubles you have…
have manufacturing in other countries been explored? wonder what the discrepancy in costs would be for more capability in delivering what you’re asking for in coils alone…
I can honestly say that I have spent more time than you would believe trying to develop the ICES-PEMF coils and have them built properly at a reasonable cost. If everyone is willing to pay about $150.00 per pair, then it would be no problem at all 
I’m back at it again working with tape. the Teflon tape didn’t last long with exposure to body heat over time… the adhesive wore off and the tape began to unravel. 
I’m looking at stronger adhesive that is more heat resistant. have you @Bob (or anyone) had any experience with 3m thermosetting glass cloth tape?
this looks promising for an adhesive that won’t fall apart over time. i plan to add and tape the loop to the coil this time to alleviate tension at the connection of wire to coil.
will see how this plays out once i get my new coils replacement 
Anything flexible placed close to the body during movement is in an extremely harsh environment. Very few things can withstand this constant hammering the way skin can.
When I had a lab at MIT, the #1 challenge for bio-inspired robotics was trying to find something that could simulate skin. Nothing synthetic that we have is as tough, soft, and flexible as skin. This is hard to believe, but it is true.
We are constantly trying to improve coil durability. If anyone finds anything that works better than what we currently do with coil reinforcement, please let us know because we have tried everything we can think of. We have asked every factory for every improvement they can think of. I reviewed several proposed improvements last week. They were not really improvements, unfortunately.
Keep in mind that most materials will be very irritating or damaging to the skin. Some people can tolerate things such as glass cloth tape, but most people would find it very irritating.
I’ve been using the coils nightly, sleeping on top of them. have you @Bob had issues with the connection breaking in the grey ring itself? the connection at the medical rubber ring and black wire looks intact, but sure, i suppose the connection could still be broken that may be covered by the grey rubber.
i think it’s the regular movement every night, during the night with the pressure of my weight pushing into the ring sometimes adding enough weight to possible put a slight bend into the ring itself 
my question for a possibly quality, “cheap fix” to extend the life of the wires/coil: can you make a snap on, hard plastic jacket with a wire tension boot on the black wire to encase the coil and part of the black wire? the alternative I’d considered was to use some kind of hardening epoxy over the coil and wire…
would that be a good solution? i understand it may lessen the magnetic pulse, but thinking that the trade off in signal strength might be negligible (?)
hmmm… hope that all made sense haha
@OptimalHealth knows this, but to bring others up to speed:
The point where wires meet thicker or harder objects is always a point of breakage for wires. Technically, this is called a “mechanical impedance mis-match”. All that means is that you have a mechanical connection between something hard and rigid to something soft and flexible.
There are all kinds of designs and attempts to prevent breakage at this intersection, and so you will see stress and strain relief between wires and the points where the meet with connectors, called a “strain relief”:
These work pretty well if there is limited movement at the joint. The unsolvable problem is when you add a lot of movement over a long period of time to the wire connection point.
Anything in close contact with the human body is subjected to a lot of movement: bending, twisting, stretching, etc. Think of a pair of headphones: if you wore them all day and all night, every day and every night, in a few weeks you would expect the wire to break. This would happen to any type of headphone wire, no matter how well designed or expensive.
When a wire of cable is subjected to this type of constant stress, you only have two options:
1 - Make it heavier, thicker, bulkier, stiffer, and more expensive
2 - Make it disposable: replace it when it wears out.
Every single properly designed object you will ever encounter has a balance between these two extremes. Some types of things, such as bowling balls, tend to last a longer time because they do not have wires attached to them that get twisted every day. But just think abut it: How many objects have you ever seen that age well and work for decades that have wires sticking out that get bent and twisted every day. We are not talking about an old TV set in the attic. We are talking about something you use every day. And biomedical devices with wires sticking out: that’s always the hardest design problem.
So, over the years I have spent a lot of time trying to find that balance between durability, cost, bulkiness, and ease of use.
To answer your specific question: how about a hard plastic cover over the wire?
This actually is a pretty intuitive answer: if it breaks, make it stronger.
Well, when we tried that about 10 years ago the result was predictable. The wire did not break inside the plastic cover, it broke at the edges of the plastic cover. If you extend one of the edges to cover the entire coil, then the wire does not break at the coil, but it does break at the other edge of the plastic cover.
OK, great, then extend the other edge of the plastic cover to stiffen the entire cable…
… but then the stiff cable will break the audio connector socket at the PEMF generator device.
The only way to prevent a wire breaking is to shield it entirely from the human user, from end-to-end. This means that you entirely lose the flexibility of a thin cable where you can place the coils wherever you want them, but it does solve the wire breaking problem.
As it turns out, I think this is not a bad solution if your PEMF device is small enough to have an internal coil (no exposed wire cable). Then, you need to place the device where you would place the coils, but that will solve that problem with the coil wires breaking.
As it just so happens, I am designing a new product which is essentially a model M1 with an internal coil, powered by a 9 Volt battery. I am building the prototypes on my 3-D modeler right now as I write. It would be about the same cost as our existing model M1 but somewhat larger to fit a 9 Volt battery. I am tentatively calling it the model M9. I’ll be testing it in about 2 weeks. I don’t have an image yet because it is still in early development.
Wow, way to rethink how to simplify your technology for a broad set of use cases! “Buy this device, turn it on and put it over the spot that hurts” takes away a lot of the user education and makes it “just work, without user knowledge of any kind”. The marketing side of me (versus the engineer side) would love to see better differentiation in product names that are more consumer obvious, but of course, that is up to you 
oo a practical 9v powered device… what a nice bonus to the upgraded model. #cantwait!
“M9” is just a working name for prototype development. It may change.
But nonetheless, I tend to break away from anything that is calibrated for the average consumer. Long story, but the bottom line is that in my opinion PEMF is still too early in development as a technology for the typical mass-appeal approach, so I steer away from catchy names, over-simplified product descriptions, click-bait promo videos, etc.
It’s anti-marketing. It has become my signature style 
I will be making and testing prototypes over the next few weeks. I hope to have the first prototype in about 10 days. If any of our super users on this forum would like to get one as a beta test, I’ll make them available at my cost (plus a bit for lunch). If we find that major design changes are needed, we’d make those changes as part of the beta test.
Keep in mind: this will be a very early beta test; normally I test things for about 5 or 6 months before even mentioning it. On the other hand, it is based on the model M1, so the circuit is (mostly) well established.
That’s a great point. You know your target market and where ICES PEMF is on the adoption curve. You know your signature style and are always consistent. All awesome.
well, marketers say I’m an idiot, but to me this is not just about boosting sales.