What resin to use for the search coil

[Gosho]

What type of resin should i use for the search coil?
With epoxy it will be near 1,5Kg, give me idea of other material.
Link of manifacturer if possible

[Reg]

Hi,

You can use your present resin and just add a lot of microspheres to reduce the weight. You will have to experiment a little to determine just how much is too much.

The microspheres will reduce the weight dramatically since they will take up much of the physical space.

Also, you can reduce the overall space the epoxy will be filling by adding other type foam as an additional spacer in the larger open areas.

Finally, I have used other materials such as resins such as Feather Lite from Smooth-On.

Here is a link:
http://www.smooth-on.com/liqplas.htm

I even add the microspheres to the Feather lite to reduce the weight even more.

Finally, if you are making a mono coil or even a DD coil to be used on a PI, you can try something like a simple two part foam that is rigid when done. I use a simple 2 lb type I get from Iasco-Tesco. Here is the link:

http://www.iasco-tesco.com/2PTFOAM/2PTFOAM.htm

The foam is a little tricky to work with because you have to be quick and apply pressure to the two halves of the abs plastic housing so the expanding foam doesn't push them apart. Care has to be taken to not use too much. Again, this takes practice.

Finally, you can use both, initially filling 1/2 of a two piece coil housing with foam, cutting and filing it so one half is full but flush with the foam material, cutting out a specific area were the windings are to lay, making sure there is adaquate space around the windings, and then place and seal the windings themselves with a resin of some sort.

In all cases mentioned above, the coils are much lighter.

Reg

[Largesarge]

Reg, I wonder how the EZ Cast from Iasco-Tasco mixed with microspheres would do for potting coils, it would definitely be ridgid.

[Reg]

Hi Dennis,

To be honest, I have not tried the EZ cast, so I can't say for sure just how it would work. However, I see no reason whiy it shouldn't work.

Since my coils are to be used on one of my PI's and used over dry ground, I simply use the rigid foam as a filler now. This makes a very light coil that works well.

This is about as light as I can make a coil and still have the windings reasonably rigid. Since I don't scrub my coils or beat the ground with them on a regular basis, I don't have any problems.

I do lace my DD windings together at the point of crossover before filling the housings with foam, to minimize potential problems of serious missalignment. Fortunately, alignment of the windings on a DD coil isn't that much of a problem on a PI as it is on a VLF. So, small shifts are not even noticed by me since I have my coils built with a few usec leeway.

Once filled with the foam, the coils are reasonably solid, stable and basically waterproof, but I don't try to use or submerge them in water.

Reg