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 45 users online :: 4 registered, 0 hidden and 41 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

QDV housing construction method

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
Sponsored 
  • Author
    Message

QDV housing construction method

Unread postAuthor: saefroch » Sun Apr 03, 2011 10:14 am

Since the main difficulty right now with the building of QDVs is the ability to construct a housing that's usable at very high pressures, I'm proposing a solution, which I hope I can make use of. While it's not genius, I don't think I've seen it proposed anywhere before.

Taking a threaded cross or tee, thread in four nipples, all of which are smooth on the inside. Prepare a "spacer," something with the same OD as the ID of the two nipples the piston will slide through, and long enough that when placed inside of the cross or tee, it protrudes from both ends significantly. Polish and lubricate the spacer. Fill the cross or tee with epoxy YAY!, then slide out the spacer and drill out the ports perpendicular to the spacer through the nipples, which are probably permanently attached now.

Thoughts?
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Unread postAuthor: mark.f » Sun Apr 03, 2011 10:27 am

It's a good way of keeping o-rings from being chewed up on the edges of the nipples, but what's to stop you from just using a tee in the same way?
  • 0

User avatar
mark.f
Donating Member
Donating Member
 
Posts: 3464
Joined: Sat May 06, 2006 11:18 am
Country: United States (us)
Reputation: 21

Unread postAuthor: saefroch » Sun Apr 03, 2011 10:37 am

To really take advantage of the extra flow in a QDV, I think Tech has said you'd need to use a cross design, but I guess there'd still be some improvement with a tee. The idea is that this construction method would produce a design that is internally almost identical to Tech's QDV constructions.

Male tees are rare and very expensive, especially for larger sizes. Male crosses don't exist, to my knowledge. I hope that answers the question... :? It was a little unclear.
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Unread postAuthor: Technician1002 » Sun Apr 03, 2011 11:00 am

I've considered using a 4 inch T, a pair of 4 inch to 2 inch reducers, and a 2 inch pipe in the traditional coaxial QDV design. The reducers would have the threads filed out till the 2 inch pipe fit, then welded together. It should be good for high pressure.

It would be a 2 inch QDV coaxial in a 4 inch T.
  • 0

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

Unread postAuthor: saefroch » Sun Apr 03, 2011 11:02 am

It's the welding/brazing issue that's even a more serious problem than price, in my opinion. Most members of spudfiles cannot braze or weld (I certainly can't), but all of us can purchase and mix epoxy... I hope.

I see no reason that design wouldn't work, but the ability of most to build it is questionable.
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Unread postAuthor: Technician1002 » Sun Apr 03, 2011 11:10 am

It should work with epoxy. With balanced force on the insert, the epoxy is mostly needed just for a seal.
  • 0

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

Unread postAuthor: clemsonguy1125 » Sun Apr 03, 2011 11:53 am

I think I get it but would you mind making a sketch. If its what im imagining, it would work I think. The piston could easily be made from washers and a bolt to I think.
  • 0

Last edited by clemsonguy1125 on Sun Apr 03, 2011 3:12 pm, edited 1 time in total.
User avatar
clemsonguy1125
Major General
Major General
 
Posts: 1485
Joined: Tue Jul 21, 2009 4:00 pm
Location: East Coast
Reputation: 1

Sponsored

Sponsor
 


Unread postAuthor: saefroch » Sun Apr 03, 2011 11:54 am

What do you mean by the "insert?" If you're referring to the epoxy, it should be "epoxied" onto all surfaces inside the cross/tee and be completely stationary... that's assuming I find some way to roughen the inside of such a fitting.
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Unread postAuthor: Crna Legija » Sun Apr 03, 2011 12:19 pm

if your using galvanized fittings the insides are rough enough already but you can use a broken drill bit to add a bit.
  • 0

'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson

Add me on ps3: wannafuk, 8/11/11 cant wait
User avatar
Crna Legija
Major General
Major General
 
Posts: 2333
Joined: Sun Jul 20, 2008 5:14 am
Location: australia
Reputation: 0

Unread postAuthor: Technician1002 » Sun Apr 03, 2011 12:43 pm

Take a 4 inch T. Screw in a couple 4 inch to 2 inch reducers in both ends. Now a somewhat long pipe nipple can't fit all the way through the T, it can only screw into one end.

File out the holes in the reducers until the pipe nipple can fit through the reducers.

Cut slots into the 2 inch pipe the same way they are done in a coaxial QDV and glue it in place so the threaded ends of the nipple stick out both ends of the T. The cap and knob goes on one end and the barrel screws on the other. The middle of the T screws onto a chamber if you haven't figured that one out.
  • 0

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

Unread postAuthor: saefroch » Sun Apr 03, 2011 2:31 pm

Technician1002 wrote:glue
Yeah... Don't really like that part. I was fully aware of the rest of the construction process, and even that you've suggested fitting a nipple into a tee by removing the female threads in the tee and brazing/welding/gluing now? them together. My biggest qualm about gluing a QDV together is not only that the impact of the piston may separate the two pieces depending on where one is holding, but simply the use of glue itself (or maybe epoxy?) to hold a hybrid or high-pressure pneumatic together.

I understand where you're coming from Tech, I really do. I just think that my method merits consideration as much as yours does. I guess the biggest reason I posted this is for people to voice concerns about the integrity or effectiveness of this before I try it and risk sacrificing $37 of pipe fittings and a significant amount of epoxy.

Crna Legija wrote:if your using galvanized fittings the insides are rough enough already
I probably won't be, because I've had issues with the threads undergoing some interesting corrosion reactions to permanently attach themselves together in the damp air of my basement. Do you have any other suggestions on roughing up the inside? Would a wire wheel (or whatever they're called) work?

Does greasing a fitting prevent epoxy from adhering?
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Unread postAuthor: clemsonguy1125 » Sun Apr 03, 2011 3:14 pm

Wire wheel should work or just using a drill bit and scrape it along the edge as its spinning/
  • 0

User avatar
clemsonguy1125
Major General
Major General
 
Posts: 1485
Joined: Tue Jul 21, 2009 4:00 pm
Location: East Coast
Reputation: 1

Unread postAuthor: Lockednloaded » Sun Apr 03, 2011 6:03 pm

Well since it's not actually holding significant pressure, and it's supported by the cross; roughening the inside won't matter that much
  • 0

I love lamp
User avatar
Lockednloaded
Major General
Major General
 
Posts: 1558
Joined: Thu Sep 03, 2009 9:38 pm
Location: Texas, USA
Reputation: 0

Unread postAuthor: saefroch » Sun Apr 03, 2011 6:49 pm

That's probably true. I think the most dangerous flaw is an air bubble in the epoxy, on combustion that could cause a localized collapse and serious failure :(.

As soon as I get my hands on a little more moolah and some epoxy, I'm going to try this out.
  • 0

User avatar
saefroch
Major General
Major General
 
Posts: 1679
Joined: Mon Jun 08, 2009 8:47 am
Location: U.S.A.- See Map
Country: United States (us)
Reputation: 0

Unread postAuthor: Crna Legija » Sun Apr 03, 2011 9:28 pm

i used spray on cooking oil to stop epoxy sticking, worked great don't see why grease wouldn't.
  • 0

'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson

Add me on ps3: wannafuk, 8/11/11 cant wait
User avatar
Crna Legija
Major General
Major General
 
Posts: 2333
Joined: Sun Jul 20, 2008 5:14 am
Location: australia
Reputation: 0

Next

Return to Construction Materials/Ammo Discussion

Who is online

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

Reputation System ©'