6 replies to this topic

[Mr BadWrench]

got this in my head... finalizing the details... will it work??

[roboman]

Is the 1/2 PVC supposed to move?

[Mr BadWrench]

the only piece that moves is the rubber disk

[flashflint]

Just looking at it I would have to say, no. Especaly if those proportions are the same you are using in your gun. I suggest going to http://www.spudfiles...-posts-f11.html and looking for something on how to build a piston cannon and adapt it to your needs.

[Mr BadWrench]

Piston cannon with coaxial reservoir...

I think with some refinement, it could function. No idea how well.

I would replace the magical rubber disk with something that occupies more lenght in the 2 inch bore, though. I think your disk could get sort of sideways and jam too easily. Something like a cap of maybe 1.5 inch size, with a rubber seal inside to form the barrel seal. It should be small enough to slip pretty freely in the 2 inch, maybe with some strips of low-friction material glued on to help it slide without being loose, while letting air pass around it.

ok, thanks.... I have a spudder built like this and it shoots well when it works but its really temperamental about air pressure. about half the time it just "leaks" the air out the valve instead of activating the piston. I have a bag of 2inx 1/2in rubber disks similar to hockey pucks, they fit fairly tight in a piece of 2in pvc and they do not bend easily.
Don

[Croc]

This will work, it just might take you a while to reload it. I saw instructions for a similar gun elsewhere, but it was made to shoot either marshmallows and marbles. Building pressure, then offsetting the pressure to fire. I don't know how far it would shoot though. I'd guess some decent ranges, at least 50-60 feet. The half inch thickness should be perfectly fine.

For those wondering how I have such a low post count and low member number, I have been lurking...

[CaptainSlug]

You're trying to design an integrated QEV, but your chosen poppet is not the right shape to work as you're intending it to.
It needs to have a guide of some kind to allow it to slide. It also needs to seal only on it's opposing faces, not at its edge.