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C41p50 - First Build, Strict Conditions

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.
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Unread postAuthor: POLAND_SPUD » Mon Oct 01, 2012 11:05 pm

could you maybe be a bit more descriptive
lol and you less descriptive ?

just put a reg -> ball valve as safety -> 3 way valve -> piston/toolie valve



anyway I'd be more worried about the whole idea of using this gun >>> either to dangerous to be used in PB or airsoft or so wimpy & inaccurate it almost doesn't make sense to use
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Unread postAuthor: thatguydionysus » Tue Oct 02, 2012 11:01 am

Okay, the problem with that design is that I would have to manually turn the safety back on after charging before firing. Something I prefer would be automated. Like it is in the current design. (current design allows me to keep my hands on the grips until reloading, the safety is controlled via pilot and is used really only to turn off the safety)

Otherwise What I expect to happen is when I open the pilot, the piston won't be able to push back against the supply force and I'll have effectively created a very large air nozzle.

Or

When I open the pilot I have to hold it open to allow enough pressure to be continually released for the piston to open fully. this is undesirable waste of tank air, and/or, firing time.

I came across something called a Piloted Check Valve. but I can't find anywhere that sells them at 1/2" size. heck even at the 3/8". that would, at the very least reduce some of the hand crafting I'll need to do. (the safety valve is a modified Tee Piston valve.

On a side note, I've been trying to find a compact 1/2" air regulator. anyone know where I can find one?
(yes I did check the helpful links page and the sites, but most of the regulators I found are fairly large, I'm looking for something small and simple, as far as regulators go at least Xp)
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Unread postAuthor: POLAND_SPUD » Tue Oct 02, 2012 12:00 pm

uhmm just get a toggle 3 way valve... after you press the lever you have to reset it manually to fill again - that's safe enogh IMHO

plus you should pressurise the gun after loading so that makes even more sense
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Unread postAuthor: thatguydionysus » Tue Oct 02, 2012 8:57 pm

can't load if you pressureize first. pressure in the charing chamber would prevent you from pulling the bolt back.

already using a three way as the master safety. the on/off serves as the intermediate and is automatically actuated. the pressure in the chamber causes it to close when supply pressure =pressure in the tank.

and I have a continuous air supply, it isn't ever disconnected...

And really there is no point to building this gun than just because. do I need a better reason?
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Unread postAuthor: POLAND_SPUD » Wed Oct 03, 2012 9:22 am

And really there is no point to building this gun than just because. do I need a better reason?
well I prefer to focus on the whole idea first, feasiblitity etc. and only then I concentrate on details
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Unread postAuthor: thatguydionysus » Wed Oct 03, 2012 10:39 am

Okay, well if you need a better reason, I would say its a proof of concept.

The whole idea is to create a launcher that fires a larger than average projectile, and can do so multiple times without the hassle of turning the whole system on and off.

And as far as feasibility, it can be done. I've already established a means of doing so. I am simply exploring the likely possibility of a better means of achieving the same thing.

I expect through a valve system I may not have considered or even known of.
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Unread postAuthor: POLAND_SPUD » Wed Oct 03, 2012 11:48 am

this is as simple as it can be
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Unread postAuthor: thatguydionysus » Fri Oct 05, 2012 10:46 am

So, there aren't any valves that would simplify the existing system?
Or better yet, make it more compressed >,< it seems like there are several sections that could use a machete XD
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Unread postAuthor: GonzoInferno » Tue Nov 06, 2012 6:58 pm

@thatguydionysus - Like you I am building a launcher with similar parameters. I'm trying to find existing components at sensible cost. I have been trying to navigate the forums here, educating myself with what is proven design. I am a machinist, but would rather save my sanity cards and keep from designing and manufacturing an item only to later find it already exists for 15 bucks. I don't want to re-invent the wheel but yet want something new to the arena. I'm not referring to having and eating cake now. Remember that our best resource is folks like POLAND_SPUD, JSR, and BTB.
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hyup

Unread postAuthor: thatguydionysus » Wed Nov 14, 2012 11:28 am

made an updated hyup
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okay so...

Unread postAuthor: thatguydionysus » Wed Nov 14, 2012 8:57 pm

I'm looking for a valve that has 3 ports.
In, Out, and Pilot.

flow from in flows through out. when pressure is applied to pilot => ~In flow pressure, (preferably a few psi less than inflow required) the flow in will be choked. even if the pressure downstream is atm.

In order to allow flow to resume, pilot must be vented.

So...anyone know if such a valve exists?
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Unread postAuthor: jackssmirkingrevenge » Thu Nov 15, 2012 2:07 am

Sounds like a QEV would fullfill that role if I understood you correctly, care to draw a diagram so perhaps we can see what you would like to achieve better?
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Unread postAuthor: GonzoInferno » Thu Nov 15, 2012 9:09 am

thatguydionysus - Are you using this valve for fill, main valve for chamber flow, or trigger?
POLAND_SPUD wrote a piece with references you may find usefull. Search "directional control valves".
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none of the above?

Unread postAuthor: thatguydionysus » Thu Nov 15, 2012 10:23 pm

in the last picture it would be in the place of the tee section labeled "on-off".

and it's not for any of those purposes really. its there so that with a continuos supply of air, of the desired firing pressure, the valve will close when the pressure in the chamber is, approximiatly, that of the supply pressure.

and im not sure if a qev would work. from what I have seen qevs close the barrel and allow air to flow from the pilot into the chamber.

if placed in my system that would be a problem given that it would indeed seal off the supply from the chamber. but when the chamber is vented the pressure behind the pilot would immediatly flow into the chamber allowing the valve to re-open which is undesireable.

a qev could work if the pilot required less pressure close than the supply pressure. and it did not leak to the chamber.

or am I missing something?
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Unread postAuthor: GonzoInferno » Fri Nov 16, 2012 6:10 pm

thatguydionysus - I went back and re-read the posts. Aparently I misunderstood your objectives. The semi-auto part of your build is for semi-auto charging and not semi-auto loading. Is that correct?
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