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DIY 3/2 DCV (video)
Posted: Sun May 23, 2010 2:05 pm
A short while ago I posted my balanced push button valve in BtBs original post and POLAND_SPUD challenged me.
nice... I wonder who would be first to build a working high pressure 3 way (yeah MRR I challenge you !!)
It's made of:
2x 3/8" tee
3x 3/8" nipple
2x ... what ever you need to connect the pressure source and the pilot chamber of your gun.
Posted: Sun May 23, 2010 2:16 pm
Wow, great job man! Have plans to use it on any guns?
Posted: Sun May 23, 2010 3:39 pm
Very nice. Any idea how much pressure it will hold? (I'm assuming that high pressure means that it would work with co2?)
Posted: Sun May 23, 2010 3:47 pm
I'm thinking it should work very high (800 psi) and yes it will work with CO2.
Posted: Sun May 23, 2010 5:05 pm
heh I knew you'd manage to build it... nice
any chance to see it in action ??
also you've got to see this -> http://www.nfpa.com/Training-Pneu/course3.htm
it's a short animated intro to DCVs... I'll add it to the thread on DCVs but I wondering whether can you access it freely ?
(if you are told to type in first name and last name then try 'john doe' - it worked for me
Posted: Sun May 23, 2010 7:55 pm
wow that thing is awesome! how much did it cost you to make, and can you easily reproduce it, or was it too many custom parts and machining?
Posted: Mon May 24, 2010 7:37 am
I've build a little test setup to show you guys that the 3-way actually works quite well.
Yes it is easy reproducible but you need a lot of patience if you make the rod on a drill press like I did. In total the fittings cost me about 15 bucks but it would be cheaper when you use steel fittings. The nipples should be brass though because at these points you need a smooth surface and some precision.
Posted: Mon May 24, 2010 7:47 am
I have to make this. I always have a hard time understanding pneumatics, so I want to ask you if you would do a diagram video, like you did with the barrel sealing piston valve. BTW I am butaangas on youtube. With that said, this is the first time I ask a video request.
Posted: Mon May 24, 2010 8:21 am
nice I am surprised that you decided to build a spool valve... it seems it would be easier to build a poppet valve
I am wondering whether it has better or worse flow than off the shelf DCVs?
I am asking becasue you can find a lot of DCVs for under 15$ on ebay so the question is whether it makes sense or not?
If its flow is better then you might have built something very useful
Ohh btw you can also use the design where the spool is just a rod without o-rings... teh seals themselves are thick rubber washers sandwitched between solid spacers and spacers that have holes cut through them so that air can pass (sounds complicated but it isn't - I'll try to find pics of it)
Posted: Mon May 24, 2010 4:28 pm
very nice work, i think i might try this in 1/2 or 3/4inch pvc...
Posted: Thu May 27, 2010 11:12 pm
How exactly is the pushbutton (spring return) effect achieved without a spring? Are the diameters of the exhaust porting and the front seal not the same? ie. is the valve not balanced?
Posted: Thu May 27, 2010 11:27 pm
it could be achieved using pressure area differential but I think there is a spring there... in the vid you can see that it returns to original position even when not under pressure so there must be a spring
Posted: Fri May 28, 2010 1:42 am
I might have discovered how it works. I still have a few questions. How did he manage to make the qev so short (if you get what I mean). If you watch his other video how he made the qev, it's much larger. Also I need how he made the rod returning spring.
I drawed something that might be true.
Can someone confirm me if its true?
Posted: Fri May 28, 2010 9:59 am
You got it perfectly right, good job on figuring it out. :thumbright:
...and the reason why the piston valve is so short is because I use a very short piston. Look at the shape of the sealing gasket which makes an equalization hole unnecessary and it works like a check valve.
Posted: Fri May 28, 2010 10:35 am
POLAND_SPUD wrote:it could be achieved using pressure area differential but I think there is a spring there... in the vid you can see that it returns to original position even when not under pressure so there must be a spring
But if all the portings (nipple inner diameters) are the same then there is no pressure differential because their areas are equal, right? I don't see a spring in the video on the front end where you push so if there is indeed a spring it must be somewhere else like housed in the additional coupling on the rear in the video.
Can you confirm that there is a spring in use here?
I'd like to put together a small one of these myself and I'd like it to spring return, but I'm trying to decide whether it would be easier to accomplish this with pressure area differential like POLAND said or just simply by using a spring. When using fitting like this (nipples with a standard ID) it seems like it may be easier to construct a balanced valve first, then add a spring, rather than modify the ID of one of the nipples. However, adding a spring just means another part that I'll have to find.