SpudFiles

I am searching for a lubricant to be used in lubing an aluminum hybrid piston with a viton o-ring. Many lubricants I found will not erode the o-ring and have high temp ratings, but I wonder if they will combust upon firing the cannon. I think this may be a rare topic for a specific lubricant use. Correct me if i'm wrong. I also have some PTFE o-rings that are indestructible, but they are harder and cause more friction on the piston due to the tighter grip. I'd rather stick to the Viton since it is softer and lets the piston glide easier. I looked at liquid wrench just for fun and it looks like it might work despite being very common. Another option I thought might work is one of the dry film lubricants.

You'll need a non hydrocarbon based lubricant. Silicone may work, though I haven't used it recently.. I use Inox now, which is quite good..

You could also use lithium or moly.

inonickname wrote:You'll need a non hydrocarbon based lubricant. Silicone may work, though I haven't used it recently.. I use Inox now, which is quite good..

You could also use lithium or moly.

Sweet..thanks. I saw some stuff from mc master based on those.

You can use a dry lubricant, like carbon (or graphite, forget which) powder.

rp181 wrote:carbon (or graphite, forget which)

Graphite is carbon.

But that aside, it's normally sold as graphite lubricant. Surprisingly effective.

silicon grease is the way to go i have used it for most of my lubrication purposes.

Hope that didn't come out sounding too wrong lol

would carbon graphite be a good lubracant for a home made hande pump ..

using a copper pipe and an o ring??

FORE!!!! wrote:would carbon graphite be a good lubracant for a home made handle pump ..

using a copper pipe and an o ring??

i used lithium grease for my pump

Graphite is a allotrope of carbon, not carbon. You don't see people buying carbon rings, rather diamond rings.

That aside, I would try for a dry lubricant, less messy, and it could also be used as a selling point.

rp181 wrote:Graphite is a allotrope of carbon, not carbon.

If we're being pedantic - aN allotrope.

You don't see people buying carbon rings, rather diamond rings.

I bet you I can find people who buy carbon rings.

... Benzene, for example, has its uses.

Graphite works well as a dry lubricant because while the bonds which lay flat across the hexagonally shaped carbon atoms are extremely strong, the bonds between each layer are non existent. This means the layers can slide across each other easily.

Carbon is basically only found in allotropes/fullerenes, mainly graphite and diamond, but also C60 nanotubes and buckminsterfullerines. Good quality charcoals can be around 90% carbon.

Have you considered using a different piston without a lubricant? You might be set on aluminum, but if you used teflon and machined it to a polish there would be essentially no need for a lube.

Moly grease (Molybdenum disulfide) behaves similar to graphite and can be used as a dry lube:
http://en.wikipedia.org/wiki/Molybdenum_disulfide

Lithium grease seems to nail what you want near perfectly..Although graphite would also work..

Lithium grease adheres well to metal, is non-corrosive, and may be used under heavy loads.

It also has better temperature resistance than most lubricants..
http://en.wikipedia.org/wiki/Lithium-based_grease

Silicone also sounds good. It shouldn't damage any materials near it and will help your o-rings out..
Silicone grease is commonly used for lubricating and preserving rubber parts, such as O-rings. Additionally, silicone grease does not swell or soften the rubber, which can be a problem with hydrocarbon based greases.

For what it is worth one of my old unpublished cannons used carbon graphite for a piston lube.

To get it out of the way.. the design itself was an early piston design with a very long piston. It used an o ring much like my QDV, and the piston sealed ports in the barrel that were too small. It sealed inside the barrel to prevent the o ring from blowing off.

Now that that is out of the way, the dry graphite doesn't "wet" the surfaces, so it doesn't seal nearly as well as grease wetted o rings.

Your mileage may vary.

Besides graphite you can also get finely powdered teflon. Check near the keys at the local hardware store, they should have both graphite and teflon dry lubricants for use with locks.

I'm with Tech though, a liquid or semisolid lube is probably going to seal better.

You could probably just use SAE30W motor oil. Yes it'll burn to some extent but even in a full-auto 15x hybrid it doesn't burn that much.

Dow Corning has some excellent o-ring greases that I have used in Industral applications. I have used this family of silicone based lubes;

http://www2.dowcorning.com/DataFiles/09 ... 09534a.pdf

I don't know if the Hi temp version Molykote 44 is good enough?

Go on their site and order "engineering samples".

Wow lots of great suggestions. I might check out that engineering sample Dewey suggested as well as a variety of small sample sized amounts of the others you all suggested and just see which works best.