Filler, Like Epoxy

[patlaw]

I need to fill some octal tube socket bases with a non-conductive filler. Someone suggested epoxy, but that stuff is expensive to fill the whole thing. I don't need anything as strong as epoxy so long as it is hard to remove and solid, which rules out silicone. Do you have any thoughts for an alternative material?

 

[Mike Davis]

Plaster or wood putty or Bondo

 

[Hmerkle]

@patlaw Maybe a dielectric silicone?

 

[smallboat]

Mixing 100% silicone with corn starch creates a moldable putty that dries hard and is not conductive.

 

[JNCarr]

Maybe a little more info please -
1) by solid do you mean hard? Silicone is solid, but you indicate that wont work.
2) does it need to be clear, colorless, translucent, opaque? Since it needs to be electrically non-conductive, perhaps you are putting LEDs in them.
3) what is the base made of - not everything sticks to everything.
4) is a little shrinkage ok?

 

[Wilsoncb]

How about plumbers putty, or that stuff they put around the Freon lines to plug holes (so the mice don’t get in).

 

[bainin]

If you want a hard silicone, you should focus on Shore D silicones. This is the hardness (durometer) scale. Shore D 50 is like as hard as a golfball.

I dont know what an octal tube base is, but it looks like some kind of electrical feedthru.

As a joke, the base you show is already filled with a non conductive filler...air

b

 

[HITCH-]

What about construction adhesive, such as liquid nails?

 

[Oka]

We used to use a white plaster that was non conductive on machines that handled flammables, not sure what it was called.

 

[patlaw]

Thanks for all of the suggestions. I will investigate each of them further. If I use silicone, it has to be electronics grade. The protected innards are zener diodes with 320 VDC across them.

 

[JNCarr]

RTV silicone.
That's a big Vz voltage! I assume you've calculated the power dissipation and estimated the temperature rise for however many (4?) diodes will be in there.

 

[patlaw]

RTV silicone.
That's a big Vz voltage! I assume you've calculated the power dissipation and estimated the temperature rise for however many (4?) diodes will be in there.

Three five-watt zeners. The expected dissipation is about 4.5 watts (total). It's a replacement for a 0C3/VR105 tube.