someone asked what i am using for a piston

im going to machine a piston out of delrin (lightweight/strong plastic material) using a lathe so it is going to fit perfectly in the chamber, along with the o-rings its going to create a good low friction seal

thanks for the help guys, if anyone else has any comments feel free to post

got another question:
what is a good material to use in order to:
1. seal the barrel
2. use as a good bumper
3. use as a check valve

i have a few technical questions about the design of a coaxial piston valve 1. how much movement does the piston need to move (i.e. in a barrel sealing design, how far from the barrel does the piston need to travel to provide the best flow)? 2. how much air needs to be behind the piston to prevent t...

where did you get those o-rings?
got any extra?

clippard.com is a good place for them
they are called "stem valves" and you can get them in 2-port up to 5-port

Solar wrote: A positive force piston valve would be a better way imho.

sorry to hijack but what is the difference between a "positive force piston valve" and a regular piston valve?

so ive decided to do a coaxial
what is the best method to dump the the air behind the piston to fire the cannon?

If you have access to a machine shop and CNC stuff try building an alias MKX launcher look alike.I haven't been able to take one apart but I believe they are a coaxial.They seem easy to build.I would try, but lack a verticall mill to cut the base. http://www.bp-usa.com/weaponry.htm .Talk to someone...

ok so when the slide valve moved, it would seal the CO2 side and fire the cannon at the same time, correct?

if i use a sleeve valve, it says when its closed it vents pressure to the atmosphere, so wouldn't it just empty the CO2 tank to the atmosphere if i close the valve?

keep_it_real wrote:You can't put the pilot valve and the co2 together like that. It might sorta work but the co2 will just go out the blow gun. Instead I would use a slide valve.

could i just put a ball valve inbetween the CO2 and the pilot valve that would get shutoff when the chamber filled? whats a slide valve?

ok, so same general design, but revised piping near the QEV (not drawn to scale)

this would be the correct layout and would function correctly?

what QEV would people suggest? with what size output/input?

thanks for all the help by the way

i just threw this diagram together using a QEV valve

would it work?

dont underestimate my mechanical ability

difficulty of construction is not a factor, im a mechanical engineer with full access to a machine shop

you mentioned "barrel sealing coaxial" are you referring to this?: http://www.spudfiles.com/forums/3-piston-t313.html

hey all, im pretty new here and i had a few questions that i hope you guys can help me with. im throwing around the idea of creating a bazooka style cannon for scenario paintball use. I want the set up to be as small as possible, but still with a decent effective range. the cannon will be run off re...