Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 71 users online :: 4 registered, 0 hidden and 67 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

valve help

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
Sponsored 
  • Author
    Message

valve help

Unread postAuthor: Crna Legija » Mon Sep 06, 2010 4:05 am

Im making a forced blow back canon and would like to have semi/full auto and was think is there a valve that would act like a three way. then with a flick of a switch be like a blow gun and have a pop off in that port?

It would have to have 4 ports set up just like a 3way then the forth would have the pop off in it. when switch to that position it should have constant flow to the pop off qev

any ideas ?
  • 0

'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson

Add me on ps3: wannafuk, 8/11/11 cant wait
User avatar
Crna Legija
Major General
Major General
 
Posts: 2333
Joined: Sun Jul 20, 2008 5:14 am
Location: australia
Reputation: 0

Unread postAuthor: jrrdw » Mon Sep 06, 2010 4:46 am

From what your describing I would use a tee fitting from the pilot port with a blow gun on one end and a adjustable pop off on the other end. Using a tee would eliminate the need for a separate 3 way or 4 way valve.
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6538
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: Crna Legija » Mon Sep 06, 2010 5:36 am

But then i wouldent get semi/full auto just full
  • 0

'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson

Add me on ps3: wannafuk, 8/11/11 cant wait
User avatar
Crna Legija
Major General
Major General
 
Posts: 2333
Joined: Sun Jul 20, 2008 5:14 am
Location: australia
Reputation: 0

Unread postAuthor: POLAND_SPUD » Mon Sep 06, 2010 6:57 am

It's difficult to achieve selective fire with a purely pneumatic system. It can be done but it requires two 3 way valves and one 2way valve.

It might be a good idea to use a solenoid valve and a 555timer or a timer relay. With a simple 3way electrical switch you can choose between single shots and fullauto. Also, f your timer is adjustable you can choose the ROF on the spot

There are two problems with this design:
1. you need to get a 555timer (either make one yourself or have it made for you) or time relay
2. you need batteries to power the timer and the solenoid (put them in hte stock - that seems to be the best idea)

There are two advantages here:
1. The gun is more accurate, since it is is triggered by an electrical switch. The valve opening time is consistent, so it also improves accuracy.
2. You can adjust ROF on the spot. With a 555 timer and some timer relays you can adjust both phases of the cycle (how long the valve pilots the gun and how long it fills it)


Anyway, fullautos are a bit tricky as they consume a lot of air and ammo... It's not a big problem if you want to use 6mm BBs as ammo but anything that requires, let say - a 150ccm chamber or bigger, is going to be a real PITA

150ccm of air at 20 bar = 3L of air
let's assume you want to achieve ROF of 5 RPS....
3L * 5 = 15L
Now it might not seems as much but with 5 RPS there are 5 cycles of piloting and 5 cycles of filling. Let's assume that means that the valve has 0.5 second to feed that 15L of air into the gun

This basically means that your system has to be able to handle that flow and that you need to have a tank that can provide enough air for it
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: Crna Legija » Mon Sep 06, 2010 7:18 am

Im using 16mm marbles its like 2 bucks for 40 rounds and i wont loose meany because i shoot at a box of sand. so far i get about 12 shot out of a 1l tank at 300psi so ill try get that much in a clip, i wanna get a new 3way because it leaks at 320psi.

sucks that i wont have select fire :(. ill probly make two pilot set ups and have a QD to hook them up quickly.

would i set the 555 the same way as a flashing light one? do you have plans?
  • 0

'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson

Add me on ps3: wannafuk, 8/11/11 cant wait
User avatar
Crna Legija
Major General
Major General
 
Posts: 2333
Joined: Sun Jul 20, 2008 5:14 am
Location: australia
Reputation: 0

Unread postAuthor: POLAND_SPUD » Mon Sep 06, 2010 7:52 am

would I set the 555 the same way as a flashing light one? do you have plans?

Yeah, but you'd probably need to add mosfet or transistor...not that it makes it a lot more complicated

ask technician or dewey for more info - I am a noob when it comes to electronics

EDIT
Ohh btw I found something that looks pretty cool -> http://www.yenka.com/en/Yenka_Electronics/
It simulates circuits, let's you design your own PCB boards, build mechanical transmitions, gears and a lot MOAR stuff... It is free for home use...

They say that it has some cool functions like programming logic for PIC and PICAX chips and that you can use the programme itself to upload the programme into the chip etc. - check it out...
SERIOUSLY this thing looks quite impressive - or maybe I am just a noob and I don't know that it sucks
:wink:
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: Crna Legija » Tue Sep 07, 2010 8:00 am

just downloaded it look pritty cool, thanks :D
  • 0

'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson

Add me on ps3: wannafuk, 8/11/11 cant wait
User avatar
Crna Legija
Major General
Major General
 
Posts: 2333
Joined: Sun Jul 20, 2008 5:14 am
Location: australia
Reputation: 0

Sponsored

Sponsor
 


Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'