I've used it on a 2" piston for over 30 shots in half a day, it only seized up when I filled the barrel with water, which leaked into the valve and took all the lube away.KamranGo wrote: I've bought some plumbing lubricant actually, it seemed to be what i was looking for, but i haven't tried it out yet. Do you find that you need to reapply it very often? and does it have a low friction coefficient?
I apply about a fingers worth on a 2" piston 8cm long and after that I can push it through 2" pipe with ease.
Btw, I say go for it. You may as well, you'll only learn from your mistakes.
I suggest you look at a pneumatic cannon called SWAT, it's on this website somewhere.
Just make sure you know what you're doing first.
Two places most common with structural failure:KamranGo wrote: However, i'm still a little bit hazy as to where you experience a lot of structural failure? or where exactly are points to be wary of? I want to still pursue building this valve and i was a little bit confused where you had experienced problems before. Though, i think this topic is starting to digress.
1) Piston housing, you NEED a really good bumper for a piston this size.
hell I need a decent bumper in my 2" piston.
You would be surprised how powerful they are.
I suggest you build a smaller piston first, as a test setup.
But with a piston this big, there is going to be huge forces involved.
2) Chamber-Tee elbow. If you have a over-under cannon, the elbow that connects the tee to the chamber is under a lot of stress.
A cannon this size will need a lot of support. I'd recommend a barrel-chamber support right next to the tee, one half way up the barrel and one at the end.