Anyone have an estimate for the bore on a presta valve? From what I can tell its about 3 millimeters... I trying to figure how much force would be necessary to open it under something like 300 psi.

1. Those are 1/8" which is significantly larger than a presta valve.
2. Those are 10$ + shipping
3. I'm not patient enough to wait for that to ship, and I have a presta valve.

I think 70 psi is a little high... so I'll go with presta. Frank, the chuck doesn't matter because im just going to be surrounding the pump side of the presta valve with high pressure, so it will automatically open an fill the other side, like a check valve, just really small.

Im thinking of using either a schrader or a presta valve as a very compact check valve in a mini pneumatic. I am fairly certain this would work. My question is what do you guys think is the cracking pressure of schrader valve? The difference between schrader and presta is that schrader has a spring ...

... did you chopshop a fire hydrant...?
edit, oops, thought you had already made it.

sorry to gravedig this topic, but where do you find piping that small?? I'm making a different sorta mini, and I need piping like that, is there a special name for it that might help me search? I'm trying not to use McMaster because of their price hiking.

I've got an o-ring that badly needs some greasing... what kind is recommended? wd40 fails. Also, what kind of grease is good for pistons?

Huff it and talk in a really high voice!

as opposed to hating more... vague... things?

right, thanks guys

I am making a mini-ish piston cannon, and I've made the piston for it, but i need to get the neoprene to stick to the face of the piston... without a bolt/screw. I tried JB weld, and epoxy, which is what the piston is made of... but the neoprene just comes off. Any suggestions? Its too small for bol...

clide, I was totally lurking your site after seeing this on boing boing, and saw the minipump series... could you post a cannon thread with inside pics of that?

Hows the flow on a fridge compressor?

now its going to take forever to get my very own sgort
apparently someone actually blew 20 grand on him... according to the "sold" and "left" amounts...

I never really tried the casino, but its gone, or at least its not working... or sumting like that. IF PCGUY took it off because it was hampering the community, I think it would help. So people don't post random stuff... like this... for spudbux... they just gamble for them...