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 46 users online :: 4 registered, 0 hidden and 42 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

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

new gun/pump issues

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

new gun/pump issues

Unread postAuthor: Filippo.san » Thu Apr 03, 2014 2:27 pm

Hi everybody. :D
My second project is pretty much finished, it's a pcp with hammer valve.
since I'm using a co2 tank i plan to reach 70-80 bar (around 1000 psi) and to do that i built a stirrup pump.
i'm having some troubles with the pump though: i reached 38 bar pretty easily with a small chamber, just to test it before to charge the tank.. but since then i can't pass 20 bar, don't understand why. it seems that the piston doesn't work well anymore, it's not fluid and it takes far longer to pump even to 5 bar. i'm using a check valve for high pressures,the chamber is not leaking, so i reckon the problem is the piston. i'm not using the piston that i've found often on spudfiles (like gipetto's easy stirrup pump), instead the o ring seals in both directions and i drilled a hole at the top of the plastic pipe, so that it refills the pump every stroke. the diameter is only 9mm, i wonder if it's possible to make a decent piston of that size.. in any case, that's the only possible way to reach 70 bar, unless i build a four stage pump :albino:
  • 0

Attachments
airgun.jpg
original project, with some small differences from the definitive one
DSC03921.JPG
da gun
DSC03923.JPG
da pump
DSC03924.JPG
DSC03928.JPG
DSC03926.JPG
da piston

Filippo.san
Private
Private
 
Posts: 24
Joined: Sat Apr 27, 2013 12:46 pm
Reputation: 0

Re: new gun/pump issues

Unread postAuthor: fenrir » Thu Apr 03, 2014 6:31 pm

Why not use a floating o ring piston? 1000 psi is a lot of air in your chamber, it will take quite a lot of pumping. There are other options as well, such as co2, or fridge compressors that can reach pressures close to your requirements.
  • 0


fenrir
Specialist
Specialist
 
Posts: 47
Joined: Tue Jul 30, 2013 10:31 am
Reputation: 0

Re: new gun/pump issues

Unread postAuthor: Filippo.san » Fri Apr 04, 2014 10:19 am

it's hard to make a piston of that size and i have to use the pump, nothing else
  • 0


Filippo.san
Private
Private
 
Posts: 24
Joined: Sat Apr 27, 2013 12:46 pm
Reputation: 0

Re: new gun/pump issues

Unread postAuthor: jackssmirkingrevenge » Sat Apr 05, 2014 7:56 am

Nifty set-up! Have you calculated your dead volume, this could be the issue with higher pressure.
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Re: new gun/pump issues

Unread postAuthor: Filippo.san » Sat Apr 05, 2014 3:16 pm

Yes sure, i tried to reduce the dead volume both before and after the check valve. I've found out that probably the o ring of the piston is of the wrong diameter: it should be slightly bigger than the cylinder and not strech when put in its seat. That's the whole thing i reckon.. Please tell me if i'm wrong :D
  • 0


Filippo.san
Private
Private
 
Posts: 24
Joined: Sat Apr 27, 2013 12:46 pm
Reputation: 0

Re: new gun/pump issues

Unread postAuthor: jackssmirkingrevenge » Mon Apr 07, 2014 6:19 am

Why don't you make the pump head like Gipetto made his, it's an easy design to replicate.
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Re: new gun/pump issues

Unread postAuthor: Filippo.san » Sun Apr 13, 2014 3:26 pm

50 bar reached with a floating o ring piston and a lot of pumping..yeah
  • 0


Filippo.san
Private
Private
 
Posts: 24
Joined: Sat Apr 27, 2013 12:46 pm
Reputation: 0

Re: new gun/pump issues

Sponsored

Sponsor
 


Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'