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First post and pneumatic!

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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First post and pneumatic!

Unread postAuthor: Tep » Fri Aug 15, 2014 11:25 am

Hi guys,

First post on the files; I've lurked for a few weeks since google lead me here but ready to make a post and share my creation with you all.

My goal was to make a workable cannon that could be made almost entirely from stock off the shelf parts. Also minimum tools and quick to assemble. (I have a decent amount of tools - no lathe / mill sadly, but working on it - but wanted something simple to start). My other prerequisites were an easy break trigger that didn't overly affect firing and shock pump filling / pressures.

The end result is a multi pump (20 strokes of shock pump :/ ) single that fires 8mm steel balls fairly straight and hard.

No damage pics At the moment, but it will put a ball through about +15 layers of standard 5mm cardboard from 5m. (At 250psi).

The DCV is held on with zip ties until I figure out a better method.

I don't think anything on the gun is especially innovative, it's a commercial qev piloted by a large hammer valve, the hammer is driven by the chamber so pressures rise equally. The valve surface area is smaller than the hammer surface area therefore it always opens regardless of pressure change. At the moment they are two separate things ( hammer and valve ) I couldn't find a long enough bolt to make them one piece but that's the plan once I get to the shops. Either way it works pretty well right now.

The shroud acts as a very effective silencer but has a fairly random design, there is no porting in the end of the barrel there is just a gap between the end of the barrel ant the most distal baffle.

The bolt is non spring loaded blow forward.

There is no detente but a small magnet embedded in the epoxy near the breach holds balls in place.

image-7.jpeg
Overall length ~600


image-4.jpeg
The workings


image-6.jpeg
Pilot valve / hammer


image-5.jpeg
Blow forward bolt (no spring return = shake to open)


image-8.jpeg
Hammer - o ring floats between washers.


More pics if people are interested.
No video at the moment.

P.s. I've never posted on a forum before so still getting used to the interface.
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Re: First post and pneumatic!

Unread postAuthor: jackssmirkingrevenge » Fri Aug 15, 2014 1:27 pm

Very nice for a first effort, standard parts but out-of-the-box thinking :D

no lathe / mill sadly, but working on it


Invest in them sooner rather than later, you won't regret it!
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Re: First post and pneumatic!

Unread postAuthor: Tep » Fri Aug 15, 2014 7:37 pm

Very nice for a first effort, standard parts but out-of-the-box thinking :D


Thank you very much!

I guess it's not really a first effort as I made a few (more traditional "spray and pray") spud guns back in the day when I lived in the country.

Invest in them sooner rather than later, you won't regret it!


Moving house to a proper place with a shed this week so more space available, just not sure how I will explain the need for it to my fiancee... I'm pretty sure that "It's for building guns" isn't going to cut it.

Image

It's on the cards though.

I finished a .177 barrel last night I think the chamber is too big for it but it has poke!

Put a standard air rifle pellet through my cardboard target into the side of my desk (skewer was shoved through make the hole more obvious).

It's a stainless steel tube that I found in the hobby shop sleeved in a few layers of larger pipe and set in epoxy. (I was originally making the shroud the size of the inner tube you can see in the photo but it was flimsy still so I chucked on the PVC. I load it through the back, have to unscrew each time, but it works for now.

photo 1.JPG
~400mm

photo 2.JPG
Rear sights are just random scrap I had lying around

photo 3.JPG
zip tie

photo 4.JPG
First shot went through this (.177 lead pellet) (Skewer was used to mark the hole after)

photo 5.JPG
About 10cm of penetration - plus the hole in my desk


Don't know why some of these are upside down... they are right on my computer
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Re: First post and pneumatic!

Unread postAuthor: jackssmirkingrevenge » Sat Aug 16, 2014 8:01 am

Tep wrote:Moving house to a proper place with a shed this week so more space available, just not sure how I will explain the need for it to my fiancee... I'm pretty sure that "It's for building guns" isn't going to cut it.


You're a man who obviously has his head fair well mounted between his shoulders, why should you need to justify anything to anyone? Take Reg Hunter's advice, do what you want to do - and start doing it before your fiancee becomes your wife if you want to avoid problems down the line ;)

*Ahem* I digress, guess you didn't come here for relationship advice.

I finished a .177 barrel last night I think the chamber is too big for it but it has poke!


It's never too big! Unless of course you want it to be quiet, but you seem to have caught the "shroud" bug ;)

Put a standard air rifle pellet through my cardboard target into the side of my desk


Welcome to spudfiles :)

For smaller calibres, remember that it's always better to up pressure than chamber size. You might want to find yourself a fridge compressor that will allow 500-600 psi to be reached with ease.
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Re: First post and pneumatic!

Unread postAuthor: Tep » Sat Aug 16, 2014 8:45 pm

Ha ha you haven't met my fiancée she'll shred you like a soft cheese...

I'm not sure what these brass fittings are rated to but I'm pretty sure I don't want to take them much past 500.

Fridge compressor will have to wait until my new lathe is installed. :( weeks away :(

Until then I'm going to work on a mechanical (spring) hammer for this thing rather than the pneumatic one, I think with a bigger chamber I might be able to get 2 or three shots before refill.

Has anyone made a rotary (revolver type) hammer / trigger mechanism that screws on to a brass fitting?? As opposed to an inline hammer like a rifle would have. Not sure if that is explained well but I think you will get the gist of it. I want to keep everything modular so it can be unscrewed and put together differently.

Edit: Struggling enormously with the hammer system... will get there eventually.
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Re: First post and pneumatic!

Unread postAuthor: Brian the brain » Mon Oct 06, 2014 2:21 pm

Nice work and welcome to the forum!


Sorry for the late reply..
I've made quite a few rotating hammers..


Image
The same cut short and restyled:

Image

Some older ones with the fittings held in wood.
The hammer mechanism held in wood aswell:


Image
Image

What materials do you have to work with...and what tools?
A basic single action hammer mechanism is pretty easy to make.
Think of a pizza with a quarter cut out rotating on a centre axle.
The cut-out is where it is blocked by a pin that cab rotate out of the way.

But then hammer weight and spring force come in..to decide on power, consistency and shot count...
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Re: First post and pneumatic!

Unread postAuthor: Tep » Fri Oct 17, 2014 7:48 am

Hi Brian,

Thanks for the reply and pics!

I've got all the normal hand tools - saws, router, sanders, bench grinder / drum sander etc. just no lathe / mill / drill press. Can work wood and have access to foam and formable 2 - 5mm plastics.

I'm still majorly stalled on this as I had to go away for work for over a month after moving house. I also spent all of my play money on a new supermotard and haven't been able to find any decent second hand lathes.

I've updated the hammer-valve pilot to be a modified Schrader valve that seals with almost no dead space against the piston space on the QEV - I'll post some pictures when I get a chance.

The Schrader actually works amazingly well and is super easy to actuate (I can make it cycle just by flicking it with my finger even at 600psi - fridge compressor is online!)

Just need to find the time to actually put together a proper grip / trigger / hammer. I'll take that concept of the simple pizza cutout idea and see what I can do. I've got something in mind, but still have to refine the plan.

I'll try to get some posts up sooner this time!
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Re: First post and pneumatic!

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Re: First post and pneumatic!

Unread postAuthor: Brian the brain » Sat Oct 18, 2014 1:19 pm

Something like this..?
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Re: First post and pneumatic!

Unread postAuthor: Tep » Thu Oct 23, 2014 9:30 am

Ha Ha
Right!

I guess I'll more or less copy that exactly but will have to work out putting it into an ergonomic frame that fits my mental image and screws on to the QEV easily enough. I may make a mould and cast something out of resin, not sure yet.
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update - at last

Unread postAuthor: Tep » Fri Nov 28, 2014 4:24 am

Finally after long long hours of fiddling around with hammers triggers and 50000 other things I gave up on the double action revolver style trigger and made an inline zip gun style trigger that is absolutely spot on!

The pilot valve is a Schrader valve with a bit of the collar cut off to expose the centre pin. The hammer is a ~10cm piece of steel rod with a spring behind it. The (sort of) trigger is just a bolt in the rod with a bit of brass tube around it that allows the "trigger" to be pulled back against the spring and "flip" off your finger giving a quick break / acceleration of the hammer.

It gets about 10 shots per fill before it starts to noticeably lose power. I can charge it with a track pump to 200psi or fridge compressor to about 400 (more if I wasn't scared it would blow up - I tested it filled to 450psi under a bunch of sand bags 10 times before I trusted it to 400).

At 200psi it hits hard enough to punch through 18 layers of cardboard from close range with a 9mm ball bearing for at least 10 shots. I have some 9mm plastic beads that go really fast (no chronograph so wont even make a guess about velocity but I can't see them in flight).

I think I will swap out the galvanised tube to a sodastream bottle with a regulator so I can take it to higher pressures in the tank and take multi shots at about 150psi. I my fridge compressor will get up to about 750 so should get a good number of shots off with that setup.

side view 1.jpg


pressure .jpg
pressure gauge is a bit optimistic at 3000psi


trigger 1.jpg
"trigger" --- not really its a zip gun design


close up.jpg
the workings


breach 1.jpg
the breach is not spring loaded it just blows forward and you shake it vertically to reopen it



I can do an exploded view of everything if people are interested... but it's all pretty much self explanatory.

Tep

p.s. For some reason the QEV performance deteriorates significantly after about 500psi anyway, I can't work out why if anyone has any insights then please share. (I know that is fairly scary to put 600 psi through one of these Chinese QEV - what can I say...)
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Re: First post and pneumatic!

Unread postAuthor: mark.f » Fri Nov 28, 2014 10:47 am

Looks good!
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