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main valve + loading mech. as one unit

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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main valve + loading mech. as one unit

Unread postAuthor: POLAND_SPUD » Sat Feb 13, 2010 5:44 pm

The idea is to combine both the main valve and loading mech into one block of aluminium.

The end product would be a relatively small aluminium cylinder more less the size of the machined T on the semiauto MKIII (probably not larger than (60mm diam X 110 length for 10.4mm calibre). There would be a couple of ports in it: for the barrel, mag, 3 way valve (used as a trigger), HPA source of air and one for chamber extension (optional).


IMO this thing would be a huge step forward in terms of compactness, simplicity and power (since the idea is to optimise it to use ~800 psi or more)

I've been trying to come up with a design that could be easily (cheaply) machined. SOmething that could be created from a bar of alu and would require to cut only to drill a couple of holes and ports in it and to lathe the bolt. So far this seems to be most promising....

it's based on this Image

but I modified it so that I could be controlled with a 3 way NO valve fed with regged down air

The only problem is to optimise it so it would be cheap to machine. There are a couple more problems with it, such as o-rings...

NOTE not everything is included in these models. Some lack o-ring grooves or some parts are not precisely postioned - I still have to improve them
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Unread postAuthor: deathbyDWV » Sat Feb 13, 2010 7:42 pm

I recently had an idea like this but had it hand actuated. I really liked the idea but all I have to construct it would be PVC... I thought that would break apart fairly quickly. I'd like to see it work.
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Unread postAuthor: Patto » Sat Feb 13, 2010 8:36 pm

looks good man best of luck :salute:
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Unread postAuthor: jrrdw » Sun Feb 14, 2010 6:54 am

The o-rings would need constant lubrication or they would break up, they are a stationary type of seal. You might think about lengthening the cylinder the bolt slides in, it looks to me like you might have a problem with air escaping through the bolt before the piston can make the seal.

That would also give the bolt better stability to line up with the piston. Other then those two things it looks like a workable idea. Nice design, I like it!
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Unread postAuthor: POLAND_SPUD » Sun Feb 14, 2010 9:50 am

you might have a problem with air escaping through the bolt before the piston can make the seal
yeah I still have to improve it and make sure that all the dimensions are right

The o-rings would need constant lubrication or they would break up
I think that paintball valves work well without lubricated air.. I guess I could lubricate them from time to time


also someone suggested dividing the housing into two parts and joining them via bolts...
supposedly it could cut costs but I'd like to know what is you opinion?
I am leaning towards this option as it would make creating the stationary oring seal between the LP side and the T much easier

(ohh in fact there already have to be two parts - as you can guess this valve would have to be serviced somehow so the bottom would have to be screwed in
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Unread postAuthor: jrrdw » Sun Feb 14, 2010 10:25 am

Saw off the back 3rd so the piston has a strong anchor, using 4 to 6 machine screw's/bolt's with machine thread to hold it on. That would make the ports easier to machine.

I would do the bigger part 1st making the smaller part of the port easier to center. Dewalt makes drill bits with built on pilots, the perfect center marker. They are costly. I paid all most 6 dollars for a 1/4 inch bit but it made the work easy and quick justifying the cost, it made it's money back 3 holes drilled!

You could lube the o-rings with what ever kind of packing greese. The front o-rings are not under the kind of condictions where the lube would be blowed out like the rear o-rings near the bolt.
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Unread postAuthor: POLAND_SPUD » Sun Feb 14, 2010 11:24 am

ohh BTW I am not planning to machine it myslef... either I'll ask psycis if he could machine it for me or I'll contact local machine shops, which I suppose are quite cheap...

I am aiming at 50- 75$ for the prototype as that's what I can spend onmachinining it ATM....
in fact I've been thinking about selling them if the prototype works the way it should and if anyone would be interested... large orders are normally much cheaper

but I am afraid that shipping might be a bit pricey so I might as well consider this as a kind of community / open source project (meaning -> the CAD file of it will be available to everyone so that anyone could have them machined on their own)


I'll try to come up with a much better model soon
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Unread postAuthor: jackssmirkingrevenge » Sun Feb 14, 2010 2:34 pm

I think one of the disadvantages is that it's too calibre specific, why not go for more common calibres like 6mm for airsoft/pellets and 3/4" for marbles?
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Unread postAuthor: jrrdw » Sun Feb 14, 2010 5:32 pm

jackssmirkingrevenge wrote:I think one of the disadvantages is that it's too calibre specific, why not go for more common calibres like 6mm for airsoft/pellets and 3/4" for marbles?


That's a good idea. A insert could be used for the smaller barrel, then take it out for the bigger barrel. Like a screw in choke/s for shot guns. The barrel ends could be flaired and the insert slid over the barrel then screwed in place, like a brake line and flare nut...
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Unread postAuthor: POLAND_SPUD » Mon Feb 15, 2010 12:43 am

that it's too calibre specific
well I am not sure about it yet. But that's probably the calibre I'd choose because I can get a lot of 10,319mm / 13/32” (4,4340g each) steel ball bearings more less for the price of 8.731mm / 11/32” (~2.66g).

I've modelled the two calibres in Chirgun pro and GGDT and they both achieve more less the same MV but 10,319mm achieves almost twice the ME of 8.731mm and has better external ballistics.

Price of both the valve and ammo increase exponentially as the dimensions increase so I assumed that larger calibres might not be as practical

A insert could be used for the smaller barrel

yeah I guess this seems like a good idea. It increases complexity a bit but not much

also since the T could be a separate part it would be possible to design it in a way it could accept cartridges (non spherical ammo) provided that the bolt travel is greater then the chosen calibre
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 15, 2010 12:52 am

POLAND_SPUD wrote:Price of both the valve and ammo increase exponentially as the dimensions increase so I assumed that larger calibres might not be as practical


For this reason perhaps it's a good idea to start small with an airsoft or 0.177" version, even in commercial terms I think this would be the most popular.
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Unread postAuthor: POLAND_SPUD » Mon Feb 15, 2010 1:02 am

I see your point.
while .177" is probably too weak and small, 6mm would be much cheaper in terms of price and ammo and could be used for airsoft

anyway I'll probably stay with 10.319mm, but design seems easily scalable so feel free to post your own models here
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 15, 2010 1:13 am

It's a question of pressure really. If people are using regulated paintball bottles or fridge compressors then 0.177" projects will definitely be viable. At "shop" pressures however you need to go up in calibre for moar power, though I'm very sure that for airsoft purposes this design at "only" 100 psi will deliver a world of pain :)

Another good selling point would be if you got it to go auto with a pop-off pilot, can this be incorporated?
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Unread postAuthor: POLAND_SPUD » Mon Feb 15, 2010 2:51 am

can this be incorporated
This is meant to be a part very similar the QEV in a way that you could machine it yourself or have it machined and then build you own gun 'around' that part.

So while there is no reason to include it here in this thread, I thinkit can be done. Pop-off should work provided that they stay open for enough time to let the valve open. The timer/full auto valve that I suggested a few months ago could also work.

On .177, 6mm, or similar calibre gun you'd probably have enough space put there a small solenoid valve together with a PLC board. With such a setup you could adjust things such as ROF or dwell time more less in the way it's done on pb guns
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 15, 2010 3:22 am

The one thing I don't like about this design is the reliance on o-ring seals, most of which are exposed to friction and therefore wear. In this regard, and ordinary QEV + blow forward valve would be more reliable, but this offers a neater and more efficient setup. The fact that you need two air sources is also a little awkward, this is from a personal perspective of trying to keep everything as simple as possible.
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