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Whats wrong with my piston valve?

Posted: Sat Sep 01, 2007 9:15 pm
by gwoloshyn
As you can see, I finished my piston valve and launcher here (my first piston). Here is the setup. The problem im having is that the chamber will fill up and the barrel does seal, however when I use the ball valve to actuate it all the air just escapes and my piston doesn't open up. Below are some more pictures of the valve.


Image

Image

Posted: Sat Sep 01, 2007 9:19 pm
by wannabie
Do you have a kind of lubricant (sp?) on your piston to help it slide more smoothly, how tight is your piston in the T?

When you say escapes im assuming you meen around the piston?

Posted: Sat Sep 01, 2007 9:20 pm
by CannonCreator
there is a number of things.

1. your actuation hole may be to big, and the air desides to escape from there.

2. Your piston may cuase to much frition and the piston sticks to the side of the Tee.

I would try to lube the piston with somehting like 3 in 1 or cooking oil

Posted: Sat Sep 01, 2007 9:21 pm
by Marco321
The pipe it seals against isn't level so it wont seal properly.

EDIT: Just saw other posts. Yeah you might need some lube and the EQ hole might be too large. if you have a spring it might be too strong.

Posted: Sat Sep 01, 2007 9:34 pm
by mopherman
what is connected to the other side of your ball valve?

Posted: Sat Sep 01, 2007 9:38 pm
by CannonCreator
mopherman wrote:what is connected to the other side of your ball valve?
I think thats were he hooks it up to a compressor to fill it bro

Posted: Sat Sep 01, 2007 9:43 pm
by gwoloshyn
Thats my quick disconnect fitting.

The piston slides very smooth, in fact i thought it was supposed to have SOME clearance around it to act as the equalization hole so i wouldnt need one. I figured the air would go around the outside of the piston you know? Maybe thats my problem.

Posted: Sat Sep 01, 2007 9:45 pm
by goathunter
I'm with marco, Your problem is the sealing surface isn't flat.In saying that the piston is warping itself due to the "suction"(pressure of air behind the piston onto a space of normal atmosphere/the barrel) of the hole.In essence when you fill the gun you are canting the piston, so that when the ball valve opens the air escapes from the tank around the enlarged openings caused by the warping and out the ball valve.The increased friction of a warped piston doesn't help it to actuate either.
Sorry buddy but you are back to square one. :cry:

Posted: Sat Sep 01, 2007 9:57 pm
by gwoloshyn
That sucks. I kinda figured it would be a 50/50 chance using that for a piston face. I guess I'll order some rubber discs and make a new piston. Just sucks that now I need to use my dremel and remove/repair/replace that cemented in pvc fitting :(
thanks

Posted: Sat Sep 01, 2007 10:03 pm
by MrCrowley
CannonCreator wrote:there is a number of things.

1. your actuation hole may be to big, and the air desides to escape from there.

2. Your piston may cuase to much frition and the piston sticks to the side of the Tee.

I would try to lube the piston with somehting like 3 in 1 or cooking oil
That would increase performance, all the air in the pilot area is going to get wasted anyway, you can't save it by having a smaller pilot valve.
So instinctivly you should think that if its going to get wasted, you may as well get rid of it as fast as possible, hence the big pilot valve. I have a 1/2" pilot valve on my piston valve thats smaller then this, it's fine.

I agree with the others, try lube, make sure the seat is pefectly flat and level(the barrel) and make sure the piston fits well, if its a bit stuck, try some lube, it can never really be too tight, and if it is too tight you will just loose pilot volume and your chamber would probably have little to no air in it anyway.

You don't have to remove it, just stick your dremel down there and then smooth it of with some sand paper. Spend a hour on it and it should be fine.

Posted: Sat Sep 01, 2007 10:06 pm
by wannabie
Mr. crowley

thats what i made my second post about but then i realised what he ment....

I think he ment the size of the equalization hole. Which would make sense

Posted: Sat Sep 01, 2007 10:15 pm
by MrCrowley
wannabie wrote:Mr. crowley

thats what i made my second post about but then i realised what he ment....

I think he ment the size of the equalization hole. Which would make sense
Okay....I wasn't quoting you, I quoted what CC said, nothing to do with you.

Yeah thats what I thought as well, guess we will soon find out.

Posted: Sun Sep 02, 2007 12:15 am
by wannabie
What? i didnt say you were quoting me. I ment thats why i edited my second post becuase i realised what he was saying.

Posted: Sun Sep 02, 2007 12:20 am
by MrCrowley
wannabie wrote:What? i didnt say you were quoting me. I ment thats why i edited my second post becuase i realised what he was saying.
Oh right, well I didn't need to know that, I don't think anyone did.

Posted: Sun Sep 02, 2007 7:13 am
by dongfang
Hey,

I made that mistake on (the first try at) my first piston valve, too. My mistake was in assuming that the valve seat (barrel end, in your case) had to be cut off at a right angle. I did that, and just glued it in - and the thing didn´t seal.

I made the next valve right by gluing some sandpaper on the from of the piston with water soluble glue, and then used the piston as a tool to grind the seat in shape (all at their places in the tee). For a different valve, I used carbon paper to see where seat and piston touched first - and carefully filed down until they contacted around the whole circumference....

If it´s really just your barrel pipe sticking down there, maybe you can salvage the rest. Like, cut it off, and file away at it like crazy. A large coarse file is better than a Dremel....

Regards
Soren