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My bovine safe 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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My bovine safe pneumatic

Unread postAuthor: notarobot » Tue Jan 02, 2018 10:39 pm

I came across this site a year ago and was intrigued with what I saw. Reading the posts took quite a while, but I kept at it. There is just so much information here. I particularly like the search on this site. One can search within a search result, a very useful tool. I eventually made the time to get to work on a simple and safe shooter for use on a farm I have access to. The picture shows my results to date. All are muzzle loaders using 100 psi air. All PVC is regular schedule 40. They are not prettyfied as this first batch are strictly experimental.

The first trial unit is the modified sprinkler valve model in the center of the picture. Barrel is 24" of 3/4 pvc. Ammo is empty 12 gauge shells with the rim ground off. They go outta sight straight up. I have never recovered one fired horizontally unless it hit something. The sprinkler conversion article on the D-Hall site was very helpful.

I soon made the second one at the bottom with a 3" barrel. Sort of a pistol model. The 12 gauge empties are simply stuck the short muzzle backwards. They are a lot of fun to shoot and go about 150'.

The third one (top) is a 5UPH4 QEV. This one is made to shoot gum balls, so it has a 24" of 1/2" pvc barrel. And it does: 427 fps @100 psi. I got the gum ball idea from the huge ammo thread and the QEV layout from the mpmrla (M Simon) posts. It will also send enpty .410 shells into the field where they also are never found. Grainger stocks the QEV's and it took a whole 3 days from order to delivery right before Christmas.

The things I learned building these as well as a few hours with GGDT are only prelude to the next step: a breech loader. I have a design for the mechanism, just waiting for the temps to rise some so I can get back into the shop.
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Re: My bovine safe pneumatic

Unread postAuthor: jackssmirkingrevenge » Wed Jan 03, 2018 6:41 am

Welcome to the forum, fellow human!

Very nice use of standard parts, well done!

Have you considered pouring something heavy into the spent shells to give them a bit more punch? Plenty of options come to mind, for example a binder like epoxy, plaster or wax in conjunction with lead shot, steel nuts or similar metal components.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: My bovine safe pneumatic

Unread postAuthor: jrrdw » Wed Jan 03, 2018 7:02 am

I'm surprised the shells with the rims ground off don't come apart, that's mighty thin brass you are destabilizing.
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Re: My bovine safe pneumatic

Unread postAuthor: notarobot » Wed Jan 03, 2018 12:05 pm

jsr:
Thanks for the compliment.
Well, I did consider putting a 1/4" lag screw through the primer hole from the inside...
I guess I am still in the "wow I'm still impressed it does anything" stage.
When I fired the first shell through the 24" barrel and it gouged the plywood backer and ricocheted all over the garage, I realized this thing had a lot more potential than I had expected.

jrrdw:
There are two kinds of shells: molded one piece and the tube and plug style.
The molded ones are the only ones that work.
Removing the metal rim and base part does leave a hole where the primer was.
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Re: My bovine safe pneumatic

Unread postAuthor: jackssmirkingrevenge » Wed Jan 03, 2018 12:34 pm

I guess I am still in the "wow I'm still impressed it does anything" stage.


We've all been there :) be careful though, this also tends to be "Wait a minute, I don't remember than hole in the garage door..." stage :D
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: My bovine safe pneumatic

Unread postAuthor: farcticox1 » Wed Jan 03, 2018 4:05 pm

We've all been there :) be careful though, this also tends to be "Wait a minute, I don't remember than hole in the garage door..." stage :D


That can happen :shock:
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Re: My bovine safe pneumatic

Unread postAuthor: Pvc primer » Sun Jan 07, 2018 2:42 pm

Awesome! 8) have you considered putting nerf bullets in the 1/2 inch barrel just for fun? If so how many fps?
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Re: My bovine safe pneumatic

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Re: My bovine safe pneumatic

Unread postAuthor: notarobot » Thu Jan 11, 2018 2:01 am

No holes in the garage door yet.
But I guess there are two kinds of spudders:
Those who have and those who will...

I hate shooting the gumball gun indoors. They explode and make a mess. They sure do clip along though.

I am converting over to a breech loader made of metal. More pressure and more power. Yeah, I know that didn't take long, but GGDT is a bad influence.

I could try a nerf projectile next trip to the farm.
I'll report results when that happens.
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Re: My bovine safe pneumatic

Unread postAuthor: jackssmirkingrevenge » Thu Jan 11, 2018 7:54 pm

notarobot wrote:Yeah, I know that didn't take long, but GGDT is a bad influence.


Isn't it though?

*tweaks small parameter*

[calculate]

oooh, twice the muzzle energy! What happens if I add more pressure...


... and so it goes :D
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: My bovine safe pneumatic

Unread postAuthor: notarobot » Fri Jan 12, 2018 2:49 am

No question about it. That one piece of software is a gem. And something of an enabler.

Here is a pic of the start of my next build. It will be a 1/2" barrel forward opening breech loader. I fully expect someone to point out a dozen or so similar builds, and won't be upset at that. I'm always open to suggestions.

I am trying to minimize mods to the parts, mainly because I know my limits and it is crazy cold in my shop.
I pigheadedly stuck with using pipe for material because it appears to be scalable up and down and most importantly, the ammo I have fits in it. Gum balls.

The picture shows the brass 1/2" Tee getting faced off for a good seal and threads removed from one end to allow the loading port to slide open. Doesn't look like it, but that tee is spinning at about 500 rpm. I love that camera for pictures like this. It is an Olympus SP-350.

EDIT:
I added another progress pic.
The brass model is coming along. I found a piece of black tube which was a pipe dimensioned tool. The inside is relatively smooth, so I decided to continue with an iron version first. The pieces are a lot cheaper as well, so screw ups are not that costly. Next I cut out the link locking parts and make a few rubber gaskets.

Also: Thanks to jsr for the reputation point bump.
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Re: My bovine safe pneumatic

Unread postAuthor: Spudinator » Fri Jan 19, 2018 6:21 pm

Glad to see a new spudder join the game, and good job on your first of many launchers. The lathe is going to remove a number of headaches and open up a lot of opportunities, you've got a leg up on many spudders with that.
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"This is so fun it should be illegal... Oh wait..."
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Re: My bovine safe pneumatic

Unread postAuthor: notarobot » Tue Jan 23, 2018 1:06 am

Thanks for the comment Spudinator. I wish I was better at lathing stuff. I don't use it to anywhere near it's potential.

A slight deviation from the more elaborate build, I had an idea that needed checking out.

The first pic shows the new pistol length barrel made from 1/2" brass nipples sleeved in 8" of 3/4" rigid copper "M" size. The use of short "modules" helps with the "keeping the ball from rolling forward or back" problem. The sliding loading port seal is a no-stop copper sleeve. I actually made one from a sharkbite push on connector, but that is a discussion for another day.
I also had to turn the brass pipe down to fit: the old brass was .845" od and the new was .832". The 3/4 copper is .810" inside.

The second pic shows all the parts ready for assembly. The "roll back preventer" is a stainless pin located behind the load port. The "roll forward" preventer is a rubber washer made to exacting specs to lodge between the two inner barrel pieces and obstruct the passage of the ammo until the pressure rises a couple of psi above 1 bar. A sharkbite end cap with a big hole bored in the end holds the inside parts inside the barrel sleeve.

The third pic shows the weapon ready for battle, complete with ammo.
Two test shots tonight registered 288 and 286 fps on the chronograph.
The others did not register anything because I had not read the instructions....

A several notes are in order:
With the price of brass tube over a dollar per inch, it looks like I may have to find another ammo if I want to continue to use long barrels.
I still want to stay away from custom made parts, even though I kinda bent that want all out of shape by modifying the pipe on my lathe. It actually rises from keeping the hardware stores as my suppliers. Nothing I have built so far cannot be done by someone with a file, drill, patience and a good hardware store. Well, except for that QEV from Grainger.
The quick connect behind the blowgun is followed by a small ball valve. I use that as an orifice to slow down the refill of the chamber after a shot by closing it almost completely. As a result, it takes several seconds to bring the chamber up to full pressure.
I know the air chamber is way too big. I need to make a smaller one for this setup.
If I keep this setup, I will replace the back end sharkbite conglomeration with a mip to 3/4 copper adapter.
And lastly, I need to build a proper stock.
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Re: My bovine safe pneumatic

Unread postAuthor: farcticox1 » Tue Jan 23, 2018 5:28 am

I like the look of it, looks familiar :?:
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Re: My bovine safe pneumatic

Unread postAuthor: notarobot » Tue Jan 23, 2018 1:35 pm

Yeah, sometimes the parts dictate the layout.

BTW, love that chamber to barrel ratio.
What is that silver cylinder between the chamber and the QEV?
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Re: My bovine safe pneumatic

Unread postAuthor: jackssmirkingrevenge » Wed Jan 24, 2018 8:10 am

Looking good! Consider a metal chamber with smaller volume for more pressure and power.

consider this little GGDT exercise I had done with a virtual 0.177" BB launcher - in each case, the amount of air is the same, but at each step I half the volume and double the pressure.

20 inch chamber at 50 psi - 406 feet per second

10 inch chamber at 100 psi - 537 feet per second

5 inch chamber at 200 psi - 684 feet per second

2.5 inch chamber at 400 psi - 830 feet per second

1.25 inch chamber at 800 psi - 958 feet per second

0.625 inch chamber at 1600 psi - 1006 feet per second

While this is just a model you can see that higher pressure leads to more acceleration, which means that you can get more performance for the same air use.
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