filling for coil build

[alcartraz]

i have a 15" coiltek blank iam making a surf pi coil i have come to the part of filling the blank originally filled with some sort of plastic resin iam wondering wot you have filled yours with and how ridged they are ? iwas thinking of polyester resin

[Skippy]

It may be worth mixing the resin with glass micro-balloons, to form what is called Syntactic Foam. It will be stiff and light, and the dielectric effect of the resin will be reduced. I have not tried this myself, but intend experimenting with the idea sometime...

[golfnut]

It may be worth mixing the resin with glass micro-balloons, to form what is called Syntactic Foam. It will be stiff and light, and the dielectric effect of the resin will be reduced. I have not tried this myself, but intend experimenting with the idea sometime...

It would be good if hollow carbon fibers were available. Chopped strand 5-10mm long.

I use light graphite shafts to assist in low mass. I use old graphite golf shaft, wrap exoskeleton on outside using kevlar thread and laquer it on - stiffens it up a treat.

S

[SVEN1]

Non conductive potting epoxy MG Chemicals 832B
http://www.mgchemicals.com/products/...ing-compounds/

[TH Jim]

In the past i have used expanding polyeurethene foam, but it is really messy! Last one i made, i just squeezed some polystyrene packing pellets in with the coil and sealed up the housing. Both worked equally well, but the second method was easier. Doubt if either will add rigidity tho.

[technos]

But you want your coil to have negative buoyancy so it can be used in water. Something it is not going to have if it's filled with air bubbles (i.g. packing peanuts). Polyester resin is a good choice, but if I was filling something with larger voids I probably would go with foam mixed with sawdust bits to add strength/weight. It might could be messy, but I would mix small quantities at a time. It has been used by manufacturers in the past.

[baum7154]

Are you going to be searching for gold objects or small gold nuggets with this coil? If so, using solid polyester resin will slow down your coil if it is in contact with or floods the coil windings. How will you shield the coil? Will the shield be the outer layer and the only part in contact with the resin? How much spacing will there be between the coil and the shield? I think the suggestion to use the micro-balloons is a good one as it will add very little bouyancy and will improve the dielectric properties of the resin.

Just my thoughts,

Dan

[Waikiki_Sweep]

CAN NOT RECOMMEND POLYESTER RESIN BECAUSE IT ABSORBS WATER

CAN NOT RECOMMEND POLYESTER RESIN because it gets wet and absorbs water becoming a little electric conductive.
I am using "marine epoxy" that used to build surfboards. It is strong, good dielectric, does not gets wet or absorbs water, UV light resistant.
Do not use Loctite 5 min epoxy or similar. After some time you will see that water destroys Loctite making it soft.