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 80 users online :: 4 registered, 0 hidden and 76 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

QEV modding

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

QEV modding

Unread postAuthor: Daltonultra » Thu Jan 08, 2009 4:53 pm

Well, I found a spring I think will work right for my QEV, now I just need to know what size hole I need to drill through the piston to allow it to pressurize from the chamber side without rendering it unfireable.

It's a 1/2" QEV from Fastenal

Image
  • 0

User avatar
Daltonultra
1st Lieutenant
1st Lieutenant
 
Posts: 282
Joined: Mon Nov 24, 2008 8:17 pm
Location: Columbus, Ohio, U.S.A.
Reputation: 0

Unread postAuthor: Lentamentalisk » Thu Jan 08, 2009 5:13 pm

Just start with a tinsy hole, and move up from there if it doesn't work fast enough for you.
  • 0

Do not look back, and grieve over the past, for it is gone;
Do not be troubled about the future, for it has not yet come;
Live life in the present, and make it so beautiful that it will be worth remembering.
User avatar
Lentamentalisk
Brigadier General
Brigadier General
 
Posts: 1202
Joined: Tue Aug 07, 2007 5:27 pm
Location: Berkeley C.A.
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Thu Jan 08, 2009 6:21 pm

Essentially the important thing is that the rate of flow past the piston is lower than the rate of flow through your pilot.
  • 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: Eddbot » Thu Jan 08, 2009 7:57 pm

while we're on the subject, i've got a QEV like this, when filled from the pilot, the air slips past on the slanted edges

Image

if i turned it around like this, and added a spring, would i even need to put a hole in the piston to fill from the chamber?

Image
  • 0

:edfirst:
User avatar
Eddbot
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 434
Joined: Tue Oct 09, 2007 6:08 pm
Reputation: 0

Unread postAuthor: psycix » Thu Jan 08, 2009 9:07 pm

if i turned it around like this, and added a spring, would i even need to put a hole in the piston to fill from the chamber?

No edd, but it would let alot of air through on pilotting.

Dalton, I would start with the smallest hole possible. Like a needle.
Maybe you should PM brian the brain.
He is the one who knows most about this.
  • 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: Daltonultra » Fri Jan 09, 2009 1:23 am

psycix wrote:
if i turned it around like this, and added a spring, would i even need to put a hole in the piston to fill from the chamber?

No edd, but it would let alot of air through on pilotting.

I think it would also tear up the edges of the piston really badly. That is exactly how mine looks inside, and there is a plastic sealing ring inside the top. If I reversed the piston like Edd suggests, the edge of the piston would hit that ring, and over time it would shred it.

psycix wrote:Dalton, I would start with the smallest hole possible. Like a needle.
Maybe you should PM brian the brain.
He is the one who knows most about this.


I'll do that. Failing his reply, I'll start at 1/32". I believe I have one in my model drill kit.
  • 0

User avatar
Daltonultra
1st Lieutenant
1st Lieutenant
 
Posts: 282
Joined: Mon Nov 24, 2008 8:17 pm
Location: Columbus, Ohio, U.S.A.
Reputation: 0

Unread postAuthor: biged » Sun Jan 11, 2009 4:29 pm

I have made replacement rubber pistons for these valves.
I used a piece of 1/4" rubber and cut it the same diameter. Beveled the edges slightly. Drilled two 1/16th inch holes on either side, with a groove cut across the bottom on the pilot side. Works lightning fast even at pressures up to 250 psi. Has only a minimum bleed through on the pilot with the groove cut.

Image

If you do not get the new rubber piston just rite, it will turn on, but not turn off at higher pressures. Took several attempts to get it rite.

I use it as a relay valve for a bb flamethrower.
http://i70.photobucket.com/albums/i110/ ... ower_7.jpg

///ed///
  • 0


biged
Sergeant
Sergeant
 
Posts: 98
Joined: Sat Jun 09, 2007 8:06 am
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: Daltonultra » Sun Jan 11, 2009 6:21 pm

That's a great idea, I may have to try that before I go drilling the factory piston...
  • 0

The Official High-Tech Redneck

"There is no such thing as overkill." ~Solomon Short
User avatar
Daltonultra
1st Lieutenant
1st Lieutenant
 
Posts: 282
Joined: Mon Nov 24, 2008 8:17 pm
Location: Columbus, Ohio, U.S.A.
Reputation: 0

Unread postAuthor: psycix » Tue Jan 13, 2009 6:37 am

The factory pistons can be bought separately. They cost just a few bucks.
So dont freak out if you think you've destroyed your QEV. :)
  • 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: Daltonultra » Tue Jan 13, 2009 6:42 pm

I can make new ones out of a hockey puck anyways. $1.05 a hockey puck and twenty minutes in the garage gets me two pistons, I figure.
  • 0

The Official High-Tech Redneck

"There is no such thing as overkill." ~Solomon Short
User avatar
Daltonultra
1st Lieutenant
1st Lieutenant
 
Posts: 282
Joined: Mon Nov 24, 2008 8:17 pm
Location: Columbus, Ohio, U.S.A.
Reputation: 0

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'