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 51 users online :: 3 registered, 0 hidden and 48 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

hose connections

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

Unread postAuthor: EphOph » Tue Oct 14, 2008 5:23 pm

You could go with 1" flexible PVC and it wouldn't restrict flow any more than a 1" sprinkler valve (put the valve on the barrel side).

The new design looks good except for the "U" fitting. I'm not 100% sure, but I think they only make those in DWV, which is very bad for pneumatics. Use two pressure rated 90 elbows instead (that goes for all other parts too). They will also be cheaper if you put the reducer bushing on the chamber side (thus using two 2" elbows instead of two 4" elbows).
  • 0


EphOph
Private First Class
Private First Class
 
Posts: 37
Joined: Wed Sep 17, 2008 5:53 pm
Reputation: 0

Unread postAuthor: psycix » Wed Oct 15, 2008 4:09 pm

If you can find PRESSURE RATED flexible pvc, then use that. If not, then simply use that over-under construction.
Way more reliable and better for the flow.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: brogdenlaxmiddie » Wed Oct 15, 2008 6:40 pm

BCITRobotics- In your diagram, you had a single 180 degree elbow piece. I just wanted to make sure that you knew those are in no way safe for use in a pneumatic. They aren't pressure rated... period.

Edit- dammit, beaten again!
  • 0


brogdenlaxmiddie
Colonel
Colonel
 
Posts: 562
Joined: Sun Jul 22, 2007 2:19 pm
Country: United States (us)
Reputation: 0

Unread postAuthor: cdheller » Wed Oct 15, 2008 8:58 pm

rp181 wrote:use a threaded busing and a hose barb.

+1
Fittings are made with threads :roll: .


"""We kind of figured that by loading our ammo (in this case t-shirts) close to the end of the barrel and by packing it tightly, pressure would build up behind the shirt and then fire it out when the pressure exceeded the frictional force needed to get the shirt out of the barrel"""

You are actually planning on firing into a crowd with this device?
?
  • 0

"A lot of what is taken for engineering fact is nothing more than somebody`s opinion when you dig into it far enough."
Henry "Smokey" Yunick, 1923-2001
User avatar
cdheller
Donating Member
Donating Member
 
Posts: 126
Joined: Wed Oct 05, 2005 5:30 pm
Location: Austin Texas
Reputation: 0

Unread postAuthor: SEAKING9006 » Wed Oct 15, 2008 9:15 pm

If you want additional pressure to build up behind the shirt, use a burst disk.
  • 0

Completed projects:
CA1 SMSS Basic Inline
CA3 PDAB Airburst Cannon

Current Project: Bolt action rifle (25x140mm + 1in shot)

SEAKING9006
Colonel
Colonel
 
Posts: 734
Joined: Mon Jun 23, 2008 3:20 pm
Location: Texas
Reputation: 0

Unread postAuthor: psycix » Sat Oct 18, 2008 4:38 am

The static friction is nothing compared to the forces acted out by the pressure so there wont be much pressure buildup. You could count the amount of presssure buildlup in psi on one or maybe two hands.

For a fast increase in pressure, use a burst disk or simply a good valve with alot of flow and a low opening time.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: BCITRobotics » Wed Oct 22, 2008 8:19 am

This is exactly what we wanted because it doesn't have all the adapters to go from the sprinkler valve to the muzzle and pressure chamber. Is it the size sprinkler valve you are using?
Image

and yes, we are firing it into a crowd. we hope to get it done before basketball season. this includes switching from PVC to maybe aluminum or something. This is just our "rough draft."

oh. I found this under the lego sight topic.

I forgot. the previous diagram wasn't ours
http://blog.makezine.com/archive/2007/11/tshirt_canon_weekend_proj.html
we saw it on youtube
http://www.youtube.com/watch?v=FgCz7C6jEIk
  • 0


BCITRobotics
Private
Private
 
Posts: 7
Joined: Tue Oct 07, 2008 9:53 am
Reputation: 0

Sponsored

Sponsor
 


Previous

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'