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Adhesives losing the battle with lubricants :(

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Adhesives losing the battle with lubricants :(

Unread postAuthor: air_dannon » Fri Mar 31, 2017 2:02 pm

Hello All,

This is a small, not quite pen-sized, pneumatic gun that gets filled to 500 psi

I have a barrel sealing piston on this "snipe stick" copper w/ brass pneumatic. The piston is a 3/4" long piece of copper tubing with one end soldered shut with a round piece of copper and then filled nearly full with JB Weld. As the copper soldered end is facing toward the barrel, it needed a rubbery material with a lubricant to get that initial seal going before the pressure does the rest. It works perfectly, but over time a problem has come up. The rubbery materials I have been adhering to the copper have been failing. Some last longer than others, but they eventually detach from the copper end.

I've tried several materials: bike tube rubber, neoprene, and most recently I took the grippy/plastic part that slides onto metal tension clamp handles and used that. The tension clamp material sealed the barrel great and I adhered it the copper end with superglue.

I thought the petroleum lubricants I was using were responsible for degrading the superglue/gorilla glues I've tried, so after some research, I decided to try "plumber's grease" or silicone grease (90% silicone, water-based). I thought this would be slippery and gentler on the bond needed on my piston, but this morning I heard the familiar sound of a piston problem. I opened it up and the rubbery end was detached on my piston again.

Am I wrong to think the non-petroleum, plumber's grease would not mess with the superglue adhesive? I was told the prior used, lithium spray grease could be the culprit in degrading the adhesion...?

Anyway, if you have experience or advice, I'd appreciate it.

Thanks,

Dan
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Re: Adhesives losing the battle with lubricants :(

Unread postAuthor: wyz2285 » Fri Mar 31, 2017 2:34 pm

What I used to do, embed a piece of rubber into epoxy, keep it in place and stops the rubber piece from expanding duo to use.
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Re: Adhesives losing the battle with lubricants :(

Unread postAuthor: air_dannon » Fri Mar 31, 2017 4:06 pm

smart! an anchor is what I need! Thanks!
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Re: Adhesives losing the battle with lubricants :(

Unread postAuthor: jackssmirkingrevenge » Fri Mar 31, 2017 11:18 pm

It helps if you use thick rubber too, 1/4" thick will stick better than 1/8".
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