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 81 users online :: 4 registered, 0 hidden and 77 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

SGTC Megah valve build

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: Velospud » Tue Feb 26, 2013 5:41 pm

mattyzip77 wrote:Hmmmm, looks like you took all of the parts from a supah valve and put them in another tee..... Very cool upgrade though!! :D


No I made all the parts at my work. A supah valves internals would not work with my 4" tee because the supah valve is based on a 3" tee with 2" ports, I did make them nearly identical though. The supah valve is a well engineered valve so I figured I would just copy it.
  • 0


Velospud
Private
Private
 
Posts: 14
Joined: Sun Feb 24, 2013 11:36 am
Reputation: 0

Unread postAuthor: mattyzip77 » Thu Feb 28, 2013 7:04 pm

You shouldnhave went with less screws holding that back cap in. Why so many?? 8 would have been plenty. This is where my supah valve broke due to all these screws.... Still nice thiugh...
  • 0

Go Bruins!!!!
User avatar
mattyzip77
Donating Member
Donating Member
 
Posts: 1249
Joined: Tue Jun 28, 2011 12:22 pm
Location: Taxachusetts
Reputation: 0

Unread postAuthor: Technician1002 » Fri Mar 01, 2013 10:39 am

My design allows for an 1" of piston movement which should be more than sufficient according to my fellow engineers.


One comment on your piston movement distance. The engineers are correct if they are going on the minimum cross sectional area of an open valve based on 1/4 the valve seat diameter. As long as the valve to piston gap has the same area as the valve outlet orifice, you should be good to go.. if you are working with water that does not compress.

Due to speed of sound, and turbulence through the valve, there will be a pressure drop through the valve. With air the pressure drop = expansion of the volume of air.

In the above scenario, air passing the gap between the piston and valve seat results in a pressure drop. If water, about 1/2 the pressure difference between chamber and valve seat and the other half from valve seat into the barrel, but your volume has EXPANDED due to pressure drop. This reduces the total amount of flow that can enter the barrel due to higher volume and lower pressure in that area.

By having the valve open slightly larger, you can reduce the pressure drop, velocity, and turbulence in the gap between the piston and valve seat. This results in Higher pressure of air entering the barrel and the air is entering the barrel at higher pressure due to the higher pressure and at lower turbulence.

I generally design so the piston as it plows into the bumper compressing it moves about 1/2 the valve seat diameter, so for a 3 inch orifice, about an inch and a half. It is ok to have less gap after the piston starts to return from the bumper. You want insane acceleration at the beginning of projectile movement in the barrel.

Pass this note to your engineers.. See if they can shed anymore insight on this. One inch will still give fantastic flow, but why limit it when you don't need to. Use a good bumper for a proper deceleration distance to keep forces minimum on plastic parts. Without one, the piston will hammer it's way out the back.
Image
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: Velospud » Sun Mar 10, 2013 5:39 pm

http://www.youtube.com/watch?v=0lv01Mm4eCw


check this video out she is a beast
  • 0


Velospud
Private
Private
 
Posts: 14
Joined: Sun Feb 24, 2013 11:36 am
Reputation: 0

Unread postAuthor: Velospud » Sun Mar 10, 2013 5:52 pm

mattyzip77 wrote:You shouldnhave went with less screws holding that back cap in. Why so many?? 8 would have been plenty. This is where my supah valve broke due to all these screws.... Still nice thiugh...


(1500LBF on end cap)/(8 screws * 1/8" wide screw *.25" thick pvc tee) = 6000psi, I think pvc can handle 11000 psi in a shear application

8 screws would give me just under a safety factor of 2, but I still didnt trust it lol. yes I agree will definitely go with less screws next time.
  • 0


Velospud
Private
Private
 
Posts: 14
Joined: Sun Feb 24, 2013 11:36 am
Reputation: 0

Unread postAuthor: mattyzip77 » Sun Mar 10, 2013 10:49 pm

Velospud wrote:
mattyzip77 wrote:You shouldnhave went with less screws holding that back cap in. Why so many?? 8 would have been plenty. This is where my supah valve broke due to all these screws.... Still nice thiugh...


(1500LBF on end cap)/(8 screws * 1/8" wide screw *.25" thick pvc tee) = 6000psi, I think pvc can handle 11000 psi in a shear application

8 screws would give me just under a safety factor of 2, but I still didnt trust it lol. yes I agree will definitely go with less screws next time.

Dont know where you got those numbers but 11000 psi seems a little or actually alot far fetched....
  • 0

Go Bruins!!!!
User avatar
mattyzip77
Donating Member
Donating Member
 
Posts: 1249
Joined: Tue Jun 28, 2011 12:22 pm
Location: Taxachusetts
Reputation: 0

Unread postAuthor: Velospud » Sun Mar 10, 2013 11:31 pm

mattyzip77 wrote:
Velospud wrote:
mattyzip77 wrote:You shouldnhave went with less screws holding that back cap in. Why so many?? 8 would have been plenty. This is where my supah valve broke due to all these screws.... Still nice thiugh...


(1500LBF on end cap)/(8 screws * 1/8" wide screw *.25" thick pvc tee) = 6000psi, I think pvc can handle 11000 psi in a shear application

8 screws would give me just under a safety factor of 2, but I still didnt trust it lol. yes I agree will definitely go with less screws next time.

Dont know where you got those numbers but 11000 psi seems a little or actually alot far fetched....


your right here dude was wrong on his website here is a legit one
http://web.mit.edu/course/3/3.11/www/modules/props.pdf
look at shear modulus of pvc = .6gpa =87000 psi
  • 0


Velospud
Private
Private
 
Posts: 14
Joined: Sun Feb 24, 2013 11:36 am
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: Velospud » Sat Mar 16, 2013 8:30 pm

Heres the completed beast and me shooting a 2002 blazer hood. This thing is stupid powerful

<a href="http://s1269.beta.photobucket.com/user/vincedahl/media/Spudfiles_zps137c405b.jpg.html" target="_blank"><img src="http://i1269.photobucket.com/albums/jj593/vincedahl/Spudfiles_zps137c405b.jpg" border="0" alt=" photo Spudfiles_zps137c405b.jpg"></a>

<a href="http://s1269.beta.photobucket.com/user/vincedahl/media/Spudfiles2_zpsc7987a96.jpg.html" target="_blank"><img src="http://i1269.photobucket.com/albums/jj593/vincedahl/Spudfiles2_zpsc7987a96.jpg" border="0" alt=" photo Spudfiles2_zpsc7987a96.jpg"></a>

<a href="http://s1269.beta.photobucket.com/user/vincedahl/media/Spudfiles3_zpsa77805eb.jpg.html" target="_blank"><img src="http://i1269.photobucket.com/albums/jj593/vincedahl/Spudfiles3_zpsa77805eb.jpg" border="0" alt=" photo Spudfiles3_zpsa77805eb.jpg"></a>

<a href="http://s1269.beta.photobucket.com/user/vincedahl/media/Spudfiles4_zpsb8ef5d52.jpg.html" target="_blank"><img src="http://i1269.photobucket.com/albums/jj593/vincedahl/Spudfiles4_zpsb8ef5d52.jpg" border="0" alt=" photo Spudfiles4_zpsb8ef5d52.jpg"></a>
<a href="http://s1269.beta.photobucket.com/user/vincedahl/media/Spudfiles5_zps53a30adb.jpg.html" target="_blank"><img src="http://i1269.photobucket.com/albums/jj593/vincedahl/Spudfiles5_zps53a30adb.jpg" border="0" alt=" photo Spudfiles5_zps53a30adb.jpg"></a>

Check out this video FEEL THE POWA

http://www.youtube.com/watch?v=8vMCmw8z ... jifwCltRYg
  • 0


Velospud
Private
Private
 
Posts: 14
Joined: Sun Feb 24, 2013 11:36 am
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Sun Mar 17, 2013 7:18 am

[youtube]http://www.youtube.com/watch?v=8vMCmw8zAyY[/youtube]

Nice. Needs better ammo than lemons though, does a soup tin fit in the barrel? An empty one could make a good sabot...
  • 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

Unread postAuthor: Velospud » Sun Mar 17, 2013 12:41 pm

jackssmirkingrevenge wrote:
Nice. Needs better ammo than lemons though, does a soup tin fit in the barrel? An empty one could make a good sabot...


I did a can of pumpkin pie filling, it was weak sauce though, I was shooting 3" diameter by 6" long chunks of oak wood in that video. No lemon is about to go through a steel hood lol.
  • 0


Velospud
Private
Private
 
Posts: 14
Joined: Sun Feb 24, 2013 11:36 am
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Sun Mar 17, 2013 1:46 pm

You'll be amazed what fruit through if fired fast enough.

Image

That clean hole in a 1/4" thick reinforced glass window was made with a high velocity orange from 100 yards away ;)
  • 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

Unread postAuthor: Technician1002 » Sun Mar 17, 2013 9:30 pm

Even a marshmallow will cause damage. :P
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: jackssmirkingrevenge » Sun Mar 17, 2013 10:26 pm

You forgot the picture ;)

Image
  • 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

Unread postAuthor: mobile chernobyl » Sun Mar 17, 2013 10:43 pm

if you have a 3" barrel I highly suggest going to the discount food store nearby and stocking up on shitty soup! The fit is near perfect, requiring almost no wadding. The destruction potential is much greater!

Here's my 3" barreled pea shooter shooting random stuff - soup cans included!

[youtube]http://www.youtube.com/watch?v=B2LyPH_EZgg&list=UUdUpfZ3xfwQ2OrPkhxo5Z5Q&index=15[/youtube]
  • 0

User avatar
mobile chernobyl
Colonel
Colonel
 
Posts: 732
Joined: Sun Dec 03, 2006 11:53 am
Reputation: 9

Unread postAuthor: Velospud » Mon Mar 18, 2013 12:46 am

mobile chernobyl wrote:if you have a 3" barrel I highly suggest going to the discount food store nearby and stocking up on shitty soup! The fit is near perfect, requiring almost no wadding. The destruction potential is much greater!

Here's my 3" barreled pea shooter shooting random stuff - soup cans included!

[youtube]http://www.youtube.com/watch?v=B2LyPH_EZgg&list=UUdUpfZ3xfwQ2OrPkhxo5Z5Q&index=15[/youtube]


Your video is great I was geeking out the entire time. I am running a 3" barrel I shot a can of pumpkin pie filling earlier this week. Definitely making a trip to our local ghetto's SaveAlot this week.

Btw what kind of camera were you using and did you have a different mic on it? Because I cant get good sound quality and all my videos make the gun sound super quiet.
  • 0


Velospud
Private
Private
 
Posts: 14
Joined: Sun Feb 24, 2013 11:36 am
Reputation: 0

PreviousNext

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'