I tried using CA adhesive on both faces of the coils, bumpy sides to no avail. Short of a two part epoxy, has anyone else had a positive result with permanent adhesion and willing to share? @Bob
Elastomers are difficult to adhere to.
The coils are molded in medical-grade TPR (an elastomer)
Very few adhesives will work well.
I have had good performance from this adhesive:
Nonetheless, I think using medical-grade fabric tape or kinesiology tape is a far better way to make stacked coils permanent.
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I’ll give that a shot, thank you. I have been using a 3M medical fabric tape but due to the nature of placement, plantar surface of foot, the coils slide apart slightly. I may have to rethink my attachment strategy so I can remove the coils when I have to get up during the night. On a positive note, they can take a pounding!
Ace wrap copy. One set of mine is wrapped, then security pinned to a Buff.
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Under cyclic compressive load they do tend to slip. On the plantar surface, that is probably the most mechanically challenging. That force will resolve to a shear load at the plane where the coils contact, which will also accelerate the same kind of slip-failure, even if glued. Let us know how well it works.
have you tried top or side of foot during the day at max and at night sleeping (or watching TV, reading, etc) at bottom of foot?
This is what I have switched to. It definitely works and has helped me keep coils in place while sleeping and walking when around the house.
I have used super glue. Clamp the coils together with large binder clips for about 2 hours. Another option, which has worked best for me is to use one or two zip ties.
@Bob - the glue worked like a charm.
@fastglycolytic - perfect idea, was so focused on CA adhesive option, didn’t even think of that. That also allowed me to attach them to a length of elastic webbing (like upholsterers use for chair webbing under seat cushions).
So now I have two options for my stacked coils. Thank you all so much, as usual ya’ll deliver the best advice.
Just to add a bit of context:
I tested almost every available adhesive that was advertised to work with elastomers. Most glues do not work with elastomers, so there were not many to test. I specifically tested them with the TPR gray elastomer that covers our coils, and also the black electrical cable sheathing (PVC, very common but very hard to glue).
The glue itself not only adheres well to elastomers, but it is also somewhat flexible itself (unlike most CA glues). The technical upshot (nerd alert) is that this results pretty good mechanical impedance matching, which minimizes stress concentration and reduces failure at the bond point.
The glue I recommended (above) performed best by far compared to all others. It adhered very well between dis-similar elastomers, and it has also proven to be very effective at building up assemblies of elastomer-to-elastomer, hard plastic (ABS)-to-elastomer, and hard plastic-to-hard plastic materials.
I use this glue now for almost all purposes. It just seems to work well for just about everything.
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One last thing to add, by way of caution, it is very thin, runny, low viscosity at room temperature, so be careful when first using it.
Yes, it is very thin and penetrates small cracks well. The companion glue, with similar excellent performance but in the form of a gel, is another one that I tested and it performed extremely well, also made by the same company (but has a pink cap):
The end result, stacked coils bonded with the adhesive above, attached to elastic webbing with zip ties.
Now if I have to get up I can just rotate the whole thing so I’m not walking on it.
Thank you all again for all your help, especially @bob
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Super creative. Thanks for sharing. Really like the rotation idea. What a great solution to the problem I have had (I was just slipping in socks and putting at top of foot, but still not ideal). Where did you get the webbing? Did you use the gel version of the glue to bond it to the webbing? Where did you get the tiny zip ties?
I got the webbing from Amazon, iCraft 3-Inch Wide by 2-Yard… https://www.amazon.com/dp/B01895EMH4?ref=ppx_pop_mob_ap_share
The glue was only used to bond the coils together.
The zip ties came in an electronics component pack, so that may require an Amazon search, I believe these are the same ones,
Amazon Basics Multi-Color Cable Zip Ties - 4-Inch/100mm, 480-Piece https://a.co/d/bxZCMwj
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