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 23 users online :: 5 registered, 0 hidden and 18 guests


Most users ever online was 106 on Sat Jun 14, 2014 4:35 pm

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

The Team
Administrators
Global Moderators
global_moderators.png CS

Balance Spool Valve

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

Balance Spool Valve

Unread postAuthor: josephlys » Mon Jun 11, 2012 9:31 am

I've looked at balance spool valves and they seem to be more reliable than close ratio T-piston valves that rely on a pilot valve to fire. If I'm using 3/4'' PVC setup, then should I look for 3/4'' o-rings or rubber washers that fit snugly, cause now what I should look for is a tight fit right. Is it difficult to get a perfect seal? Here's a rough sketch of what I'm hoping to build.
  • 0

Attachments
phpCFqDdsAM.jpg
Balance Spool QDV

josephlys
Private First Class
Private First Class
 
Posts: 31
Joined: Mon Jul 26, 2010 11:01 am
Reputation: 0

Unread postAuthor: POLAND_SPUD » Mon Jun 11, 2012 11:36 am

that's basically a QDV
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5384
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 7

Unread postAuthor: josephlys » Mon Jun 11, 2012 12:31 pm

How bad would the recoil be if I'm using light ammo like 80gr-100gr projectiles. Piston would be 500gr (30g+) the most. I'll use stacked rubber washers as the bumper. Does this look safe?
  • 0


josephlys
Private First Class
Private First Class
 
Posts: 31
Joined: Mon Jul 26, 2010 11:01 am
Reputation: 0

Unread postAuthor: far_cry » Mon Jun 11, 2012 1:05 pm

500 gram its a lot , it can break the pvc easily

make the piston lite as possible
  • 0

ImageImage
User avatar
far_cry
Donating Member
Donating Member
 
Posts: 317
Joined: Wed Aug 20, 2008 3:59 pm
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Mon Jun 11, 2012 2:03 pm

I think you will find this helpful: http://www.spudfiles.com/forums/tutoria ... 21740.html

Note that the tee has to be significantly larger than the barrel in order to allow enough flow.

500 grams for the piston sounds like a gross overestimation, but look to make it as light as possible. Alternatively, try andrepent for your sins ;)
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 23932
Joined: Thu Mar 15, 2007 11:28 pm
Location: epoxy batcave
Reputation: 50

Unread postAuthor: Brian the brain » Mon Jun 11, 2012 2:14 pm

500 gram is ridiculously heavy.
You could use a bolt and washer type piston and get a fraction of that weight.

If you have an electric drill you can easily file down the washers to the required sizes to make it fit perfect.
The idea is to use a thick rubber washer, that fits inside the O-ring ( nice fit) and then keep the O-rings locked in between two larger metal washers on either side of that.
Lock them in place with locknuts.

The rubber washer keeps the washer-to-bolt gap airtight and
makes the O-ring seal adjustable.
Squash the rubber washer and it will expand, in turn pushing the O-ring onto the pipewalls.
Ideally the O-rings should fit perfect though and don't need the adjustment to seal.

I personally prefer to use just one O-ringed seal and keep the barrel side seal flat.
Just like in a piston valve basically.
This would be better than an O-ring IMHO because it causes NO drag and it is not submitted to wear like an O-ring that needs to pop in and out of a pipe, of slide over a hole, wichever form you choose.

The trick is to get the flat sealing surface OUTER diameter ( or rather the pipe it seals onto) identical ( or slightly smaller, but only just!!) to the other sealing "surface".
Wich , in this case, would be the INNER diameter of the pistonhousing
  • 0

Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
User avatar
Brian the brain
Moderator
Moderator
 
Posts: 3360
Joined: Mon Dec 05, 2005 2:06 am
Location: Holland
Reputation: 12

Unread postAuthor: Gippeto » Mon Jun 11, 2012 3:41 pm

josephlys wrote:Piston would be 500gr (30g+) the most.


Where's Stuey when ya need him...what part of 500 GRAINS did you guys NOT understand? :lol:

Busted for NOT reading the post. :lol:

I know....I do it too. :oops:
  • 0

"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2290
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 4

Sponsored

Sponsor
 


Unread postAuthor: jackssmirkingrevenge » Mon Jun 11, 2012 3:46 pm

Ohhhhhhh.... right

carry on :oops:
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 23932
Joined: Thu Mar 15, 2007 11:28 pm
Location: epoxy batcave
Reputation: 50

Unread postAuthor: Technician1002 » Mon Jun 11, 2012 6:16 pm

I have not built one in a T with a split spool, but the one piece spools with lots of bumper performs well. Using a bumper on a bent rod will bend it lots more. Plan on a substantial bumper the spool will strike. A directly connected trigger is a bad idea. Look into ways to prevent the trigger from slamming back when triggered. it packs a punch.
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5152
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: josephlys » Mon Jun 11, 2012 10:58 pm

Gippeto wrote:
josephlys wrote:Piston would be 500gr (30g+) the most.


Where's Stuey when ya need him...what part of 500 GRAINS did you guys NOT understand? :lol:

Busted for NOT reading the post. :lol:

I know....I do it too. :oops:


Lol :lol:

Technician1002, I was weary about the trigger as well, it looked like it would have crushed my fingers. But it was a simple design with less moving parts. Oh well :)

Is there really any difference between a '2 piece spool' and a '1 piece spool' in a T, cause both look like they work the same in a T?
  • 0


josephlys
Private First Class
Private First Class
 
Posts: 31
Joined: Mon Jul 26, 2010 11:01 am
Reputation: 0

Unread postAuthor: Technician1002 » Tue Jun 12, 2012 1:58 am

A 1 piece spool is used in a small gap to increase strength. It is easy to make a 1 piece spool slide on the trigger bar. A 2 piece spool is made to reach a further distance. The extra rod in the middle adds mass and prevents use on a sliding rod. Allowing the spool to pop without smashing fingers is a good thing. The design as shown above may glance off the bumper, bending the rod in the process. A gap width in the middle of the T about 1/2 the diameter of the ID of the barrel should work well and permit the use of a short spool.

The shorter the spool travel the less speed the bumper has to endure. A balance between the distance the valve opens and how far the piston launches before bumper impact is an art to fine tune for both performance and reliability.

A spool in a T may peel the O ring off the spool as it pulls into the T. I recommend using a through pipe instead with ports to keep the rings on the spool.

One of my early designs did launch the o ring when shot with more than about 50 PSI. I've used ports instead of a gap for this reason ever since.
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5152
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: al-xg » Tue Jun 12, 2012 4:21 am

http://www.spudfiles.com/forums/paca-mk ... 21703.html

This is basically the same system as described in your first post.
  • 0

User avatar
al-xg
Colonel
Colonel
 
Posts: 643
Joined: Fri Jan 19, 2007 12:29 pm
Reputation: 0

Unread postAuthor: Hubb » Tue Jun 12, 2012 9:44 am

Look over Tech's spool valve. It is one of the best I've seen and should be able to be configured into what you are looking for.
  • 0

User avatar
Hubb
Major General
Major General
 
Posts: 2390
Joined: Mon May 28, 2007 8:39 am
Location: South Georgia
Reputation: 2

Unread postAuthor: Brian the brain » Tue Jun 12, 2012 2:35 pm

Busted for NOT reading the post


Busted for using the metric system exclusively on a daily basis and for assuming he meant gram.
Although it is technically incorrect to use gr. to indicate grams it is widely used, in my counrty at least.


I would have never guessed it should be grain...
Simply never occured to me.

:D
Ask a Dutchman or Frenchman for that matter what this means:
The more you drink, the more W.C.

I bet you he won't think of double vision...rather of a toilet.
  • 0

Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
User avatar
Brian the brain
Moderator
Moderator
 
Posts: 3360
Joined: Mon Dec 05, 2005 2:06 am
Location: Holland
Reputation: 12

Unread postAuthor: josephlys » Wed Jun 13, 2012 7:00 am

I think I'll use more bumper, extend it, add more padding. Or maybe change the trigger from L shape to a T shape. The extension will help prevent the trigger that I'm pulling from coming down on me fingers, maybe even shorten the trigger. I'll also try to cut down any unnecessary weight. Also use a T-fitting as the handle instead of a L-fitting. A 25gram spool @ 8bar shooting 5-6gram ammo doesn't sound too violent. I really like the 1 piece trigger, I'll see what can be done to make it safe to use. Hehe wish me luck, and thanks for the all the constructive feedback.
  • 0


josephlys
Private First Class
Private First Class
 
Posts: 31
Joined: Mon Jul 26, 2010 11:01 am
Reputation: 0

Next

Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], chaos cannon, D_Hall, Google [Bot], Yahoo [Bot]

Reputation System ©'