Filler for Coil shells, or filler for any coil

[surfdetector]

Yes, Epoxy, auto body fillers and boat resins are a really bad idea. They get hot in large masses, can melt your project and generally don’t stick to plastics very well. Another possibility is acrylic. Don’t have any personal experience with it but I have heard of others using it successfully.

I used this for the coils that I made for use in the water:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I lined the inside of the coil shell with mesh sheetrock tape prior to pouring the epoxy and it adhered completely. The working time of the resin is longer so the heat generation is less.

[MartinB]

I used this for the coils that I made for use in the water:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I lined the inside of the coil shell with mesh sheetrock tape prior to pouring the epoxy and it adhered completely. The working time of the resin is longer so the heat generation is less.

Great to here some success stories. The last thing I want to do is spend ages making the coil and then ruin it with the wrong type of filler. Really appreciate your positive responses.

[dbanner]

I once used tile filler/grout, or whatever you want to call it. There is zero heat, and it is light weight. Drying time is an hour or two, depending on the thickness.
That's been about two years now, the dam coil still perform perfectly, it hasn't gone out of balance even in the slightest measure.

[6666]

I once used tile filler/grout, or whatever you want to call it. There is zero heat, and it is light weight. Drying time is an hour or two, depending on the thickness.
That's been about two years now, the dam coil still perform perfectly, it hasn't gone out of balance even in the slightest measure.

Never thought to use tile grout. looked it up, seems to be different types

[dbanner]

No, there's only one type. It's the kind of thing you only know from experience. Find Ashoka tano, tell her that bo kattan sent you.

[6666]

No, there's only one type. It's the kind of thing you only know from experience. Find Ashoka tano, tell her that bo kattan sent you.

Looking through the product description, we seem to have two types , Cement based and flexible, dont know what the difference is
but is yours Cement based?

[fo0bar]

I've used dry sawdust as an epoxy filler, works GREAT. Nice and light, and makes the resin incredibly durable. Can really load it up, but too much and it gets brittle. Gives a woody colour to the epoxy. This is good for coils because the sawdust has much lower relative permeability than resin.

I also use QCells which I think are similar to microballoons, but a lot finer (microscopic, lighter than dust particles) and more hazardous. They mix and fill out very nicely and gives the resin a better flow and finish when very thick than sawdust does. Extremely strong, even when highly thickened. Can be used to further strengthen with sawdust fill. Very strong due to being perfect spheres with loads of surface area. Wear a mask.

When using resin to pot anything, I recommend "casting resin". Casting resin has a much longer pot life than general fiberglassing/household resins, and so produces far less heat. I use stuff that has a 12 hour hardening time, 24 hour cure. Gives me plenty of time to work with and fix screwups, and if I want a faster hardening time I can just add a few drops more catalyst. A slow curing resin will also reduce possible shrinkage or deformations when drying/curing.

[Matt_Rowe]

never thought of sawdust. good point