Sealing Around A Cable

[dylema]

I am currently making a little DIY canister filter (similar to this). I have managed to seal the filter intake with a bulkhead type fitting and the outlet by drilling a hole slightly too small and forcing the hose through.

I am now stuck on the cable that has to go through the lid. I tried using a bit of air line with a small hole and forcing the cord through but it leaks, I bought a couple of grommits (little rubber tubes with flange bits, made to seal a wire going through a surface) but the small one is too small and the larger one it too big. To add to the problem the cord is an oval shape not round.

Any good ideas to seal it? I would like to stay away from silicon if I can.

 

[mantis147]

Cant you just use the normal aquarium sealant that is normally used to join the glass together?

 

[dylema]

Cant you just use the normal aquarium sealant that is normally used to join the glass together?

It doesn't stick that well to the plastic, it peels of quite easily. I don't know why but its anoying.

 

[Graeme Edwards]

The way i did mine was i driiled a hole slightly too small, threaded the cable through, then because i was worreid about the silocone adhearing to the plastic ,i scored the plastic around the holes top and bottom with a stanly knife, the silocne grips the slits and gives a realy good seal.

Iv had no worries with mine at all.

 

[wendywc]

Try taking the small grommet and drilling/dremeling and sanding the opening of it for the cord.

 

[dylema]

Thanks for suggestions.

Does anyone know if silicon sticks to rubber. I could silicon inside the larger grommit. This would work if the silicon sticks. Otherwise I will try moodys scoring method.

Edit: read the packet, yes silicon does stick to rubber.

 

[SkiFletch]

Wait wait, not necessarily... There are generally two types of rubber. Silicone rubber and vinyl/butyl (natural) rubber. Obviously silicone sticks to silicone rubber, but doesnt stand a prayer of sticking to natural rubber. Natural rubber tends to be black and very "tough" while silicone rubber can be any color and is usually spongy in texture.

What is the material in the wire insulation and what type of container are you truing to seal it to? If the materials are right I might be able to reccomend a glue for you, but if not you're best option is a natural rubber gasket drilled out just-so for a nice tight seal around the wire.

 

[dylema]

SkiFletch, the cable insulation is black quite hard plastic (I can dent it with my fingernail but can't stretch it) the grommit is tough black rubber (now you have me worried) the container is a plastic food container (slighly flexible, clear) the recycle number (number inside a triangle of arrows) is pp it is freezer safe, microwave safe, dishwasher safe, food safe. Thanks for your help.

 

[SkiFletch]

Ok well, yikes, those are hard materials to work with. The wire is either teflon or pvc coated, the rubber sounds like natural, and the container is probably a cheap low-energy polyethylene or propylene. Your best bet is probably a rubber stopper. Drill a hole in the center that's too small for the wire. Then cut down its length towards the hole you drilled so you can slip the wire in there and get the rubber stopper all around it. After that, seal the cut in the rubber with a neoprene glue (like "Aqua Seal" or "Seal Cement"). Then of course, just cram the rubber stopper into the plastic container. The force on the wire from the just too small hole and the force on the container from cramming it in would take care of your sealing to the container.

The only solvent that MIGHT stand a chance of actually gluing the wire to a natural rubber stopper would be PVC cement. If the wire is PVC coated, that would work... If its teflon coated, well you know how well things stick to teflon .

Hope that helps

 

[dylema]

Ok Thanks SkiFletch. Just before your last message I had put silicon in the grommit. It seems to be sticking ok (sort of) to the grommit and the cord but the little bit I put on the plastic container is not sticking (I knew it wasn't going to but just checking). I will try the rubber stopper method that sounds good. I was thinking of trying two part epoxy adhesive but it says not suitable for thermoplastics such as polyethylene or propylene so that wont work. Thanks for the help.

Edit: Going through the different types of adhesives on the net everything sounds good until I read will not adhere to polyethylene or propylene. So many adhesives nothing sticks to polyethylene or propylene.

 

[Rooster]

Hot glue gun ?

 

[dylema]

Hot glue gun ?

Worth a shot I have one so I will see how it goes.

 

[SkiFletch]

Yeah, polypropylene or polyethylene are tough since they're such low-energy plastics. The only thing I've ever found that sticks to them is a product made by 3M over here. DP 8005 Epoxy. We use it at work for bonding nylon to polypropylene and it works great. Too bad it costs $50 for a small tube

 

[dylema]

Too bad it costs $50 for a small tube

Kind of defeats the purpose of DIY really.

 

[SkiFletch]

Yeah Stuff is amazing though, sticks a lot of hard to stick stuff together