Spool Valves

[Hubb]

For the Nerf Gun Challenge, I plan on introducing a current blaster to the pneumatics side. In order for me to do this, I have designed a spool valve to replace the spring and plunger. It is the easiest way to turn the blaster into a semi-auto blaster.

For those of you who don't know, a spool valve is the type of valve used today in Automags, which just happen to be one of the most reliable and most durable paintball markers to date.


A modified version of this valve can be found in clide's GB Semi:


Besides the QDV (which is technically a spool valve), Clide's GB Semi is the only type of launcher I've ever seen utilize this valve type. And, as I have stated, I have designed one that is more like the Automag valve, and is actually a bit less complicated than the GB Semi.

The reason I am posting this is because it may not be done in time for the contest and figured some of you guys may want to take the idea nad run with it.

Later today, I will post my current design so you guys can see just how simple this semi-auto valve really is.

[POLAND_SPUD]

Besides the QDV (which is technically a spool valve), Clide's GB Semi is the only type of launcher I've ever seen utilize this valve type

quite a lot of people have been using spool valves so it's not that there is something new about them.

I think what you are referring to in this thread is the blow-forward bolt


Though I have to say that the valve used by clide (again the one at the bottom of the pic posted) is pretty cool. I guess it could be built from a threaded rod + a couple of washers and nuts

[Hubb]

Yeah, the blow forward spool valve.

Although the QDV (which is essentially a blowback spool valve) is very similar to the blowforward spool valve, they are built for completely differnt purposes. The QDV is built for power while the blowforward bolt is built for fast action. Now if the two could be combined somehow...

Personally, I'd like to see more of any type of spool valve. Everyone's so infatuated with a piston valve (which is trumped by the QDV in nearly all aspects - flow, opening time, power, etc) that they do not pay attention to other choices that will yield better results.

And, for the record, I do believe JSR has ventured into these types of valves with his little auto / semiauto bb shooters.

[POLAND_SPUD]

you must have seen this
It combines both the blowforward bolt and the spool valve into one..

Though I don't think it makes much sense to choose this design unless you can machine it. It's useful if you want to minimize size and use high pressures with it


In my opinion it would be a better idea to use the design that PVC_arsenal, btrettel and I used...
I am sure you can find some dirt cheap 3 way valves and air cylinders on ebay... once you have all the parts you just have to join them together and that's it basically... you've got a working semiauto

[Hubb]

Yeah, I've seen plenty of designs, but not many builds. In the one I'm designing, there are no machined parts. I'm sure that the intimidation of such a valve is the main reason that they are not constructed more, but it only requires a bit of thinking outside the box to make it work.

[POLAND_SPUD]

I guess that in the end it all comes down to simplicity and ease of building...

you know, if all you have to do is to buy a couple of parts with threaded ports, join them and in the end the gun works and has great performance... so who would really bother do to it in a different way ?

I don't think you can even blame people for doing this - it's natural and the way things should be done... there is no need to choose more complicated design over a simple one unless the former is much better than the latter

and just to make myslef clear how simple and small these things can be....
(I don't think you can build anything smaller than this)