I has semiauto ;-)

[POLAND_SPUD]

ok I finally finished my semiauto marble QEV gun... I designed the gun over 1 year ago... it took me some time to finish it....

it's quite funny that this is acctually the first gun I posted here


Specs
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barrel - 98 cm of 16mm ID copper pipe {thats proper barrel lenght, that is - (overall barrel and T lenght) - (dead space)}
chamber - about 50-60 ccm (yeah I know it's smallish)
firing valve - 1/2" QEV

air cylinder - 15mm X 50mm stroke double acting; 3/8 male threads on both ends - one of them is joined with a 1/2" - 3/8" male-female adapter which is screwed into the 1/2" T which joins the QEV the barrel and 5 way valve toghether... the other one has a 3/8" elbow screwed on - just to avoid dammaging my cheek when I fire something heavier)

bolt - it used to be a part of some really old equipment/piece of junk I found in the basement... it's just a tube made from brass which has a female threads one one end that perfectly matched those one the air cylinder... surprisingly it even had two grooves for o-rings and a dimeter of 15mm... so to put it short - it's exactly what I needed and it was just lying in basement waiting for me to incorporate it into my gun

pilot valve - 1/4" 5 way solenoid spool valve... it has mechanical overide

ammo - 15mm marbles (acctually 95% of them are between 15.5 - 15.8 mm... the rest casues jams)
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I forgot to add how it works...
first of all it's just a QEV pneumatic with a 5 way valve...
The 5 way valve is for filling/piloting the QEV and piloting/filling double acting cylinder (turned into single acting one with an addition of a spring)

In one postion the 5 way valve directs air to the QEV (filling it) while at the same time venting air from the aircylinder.... in the other position the QEV is being piloted while air is being directed to the air cylinder, which, as a result, retracts....

the copper T houses the bolt.. a homemade hopper with marbles (which is not inluded in pics and the video) is joined to the upper port of the copper T...

it's all very simple and very straight forward...

so far I tested it at up to 300 psi and it works good... seals/o-rings still need some tweaking becasue some air gets past through them which hinders performance..... I realize that the chamber is rather small but I didn't know how many shots I could get with the fridge compressor.... increasing it is just a matter of time


I'll upload more pics and vids tommorow... it's 02:00 AM here... BTW Merry Christmas everyone

for now - two pics that some of you have already seen and a video showing how the bolt operates...
sorry for low quality of the video - my camera doesn't work well in low light conditions so I had to use a mobile phone

[youtube][/youtube]


EDIT
animated schematic added

[PVC Arsenal 17]

I like it! Nice job incorporating the cylinder.

[jonnyboy]

Nice gun I would make a stock for it.Do you have a high pressure source for it?

[sjog]

I aint seen it shoot nothing on that thar fincy viddeeioa.

[POLAND_SPUD]

I aint seen it shoot nothing on that thar fincy viddeeioa.

uhmm I suppose it's becasue I am just dry firing it there and showing how the bolt works... LOL you have to understand that it's 2 AM here and I had very little time for the past few days... more pics&vids tommorow

Nice gun I would make a stock for it.Do you have a high pressure source for it?

yeah I do... I have a fridge compressor... so far I am planning to stick to galvanized fittings... they are not as comfortable but IMO they look cooler.. besides I am going to try different chamber lenghts

Nice job incorporating the cylinder

@PVC Arsenal 17 it was easier than I thought... threaded fittings make life much easier...
what about yours?

[FishBoy]

Very nice, I like the way you used the 5-way valve. However, I would have waited to get some damage pics/vids before you posted. Can't wait to see it fire.

[CasinoVanart]

Noice mate:) I also await firing vids with much anticipation.
Merry Christmas

[jackssmirkingrevenge]

Judging from the video, it seems you made yourself a nice pneumatic finger crusher

Let's see it in action, it promises well and also, have you considered actually using the pilot with the solenoid in order to achieve electronically controlled full auto?:

[POLAND_SPUD]

Judging from the video, it seems you made yourself a nice pneumatic finger crusher

yeah I was fully aware how powerful air cylinders are... that's why air is used only to retract the bolt and spring pushes it forward

have you considered actually using the pilot with the solenoid in order to achieve electronically controlled full auto?:

I knew you'd ask this question of course I have... the 24V soleniod (I have one for 220V as well) works well when powered with three 9V batteries... I am fuly aware this is rather easy but I'll have to start a new topic asking for help because I have no idea what can provide electric signals at adjustable time intervals


now a dammage video... several shots fired at a bucket at circa 110 psi... again sorry for it's quality but it's already getting dark at 3:00 PM

[youtube][/youtube]

EDIT
and one more video showing basically the same setting... gamma increased slightly (it was getting dark)
[youtube][/youtube]

I'd love to show take more dammage pics and vids but again you have to understand that apart from spudguns I have my own life and things that I have to do... besides it's Christmas, it's cold and quiet outside and I don't want to atract attention/annoy my neighbors and get into troubles... be patient... I do plan to post more

[jackssmirkingrevenge]

Now you're talking should be a blast at higher pressures.

As to full auto fire, I share your ineptness in electronics to come up with an elegant solution - I'm sure others here can come up with something using a 555 or similar.

A relatively easy mechanical solution would be a small electric motor driving an eccentric cam that hits an on/off switch to the solenoid, you could then vary rate of fire by altering the voltage going to the motor.

[ALIHISGREAT]

Nice gun, i want MOAR damage!!! though

Merry christmas!

[POLAND_SPUD]

seals fixed & an additional spring added for better resealing... now it works great and it does not leak...hopefully I'll add a video on 28th... I'll still have to find a way to film long range shots (distance > 10 meters )

I am running out of ammo faster than I've thought... so far I've lost 300 marbles (that's 3 packs)

[Sticky_Tape]

Put the cammera in a metal case closer to the target than you are.

[btrettel]

I don't really have any big suggestions other than to make some sort of gigantic marble hopper and let them fly. Full auto's a good goal too.

Your bolt seems good and I think I'll use something like it in a future gun. Marbles sound like a good easy to find piece of ammunition too...

As for filming, if you have two cameras and some way to synchronize them, you could film from near the gun and near the target. This would be very nice.

[POLAND_SPUD]

I thought of that.... but thx for sharing your idea... at lower pressures flying marbles are clearly visible for naked eye but not for my camera... I think I'll do as you said and also use a piece of metal sheet as a target

well I must say I am quite surprised that there are hardly any replies... I thought a semi auto is something interesting... I knew that there were other guns using the same principle of operation before and this one is simple and very easy to copybut hey it's something quite new and original in a way... ok I'll stop complaining (I was expecitng soemthing like 'ohhh poland_spud kudosssss.... you are my god now' or something like that)

EDIT
@brettel
uhmm I don't have two cameras... and I use a 0.5L coke bottle as a hopper so yeah it has large ammo cappacity.... so far the bigest problem that I have is to get a good high volume air reservoir for my fridge compressor... a propane tank should do the job but so far I couldn't find one that'd be in a good shape.. once I find one turning it into a full aout gun is just a matter of time (not that I need a full auto gun - I'd rather stick to semi auto but it's kind of cool)

Ohh marbles are very good as ammo... if you had problems with darts you'd love spherical ammo... they are so easy to use