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Centering the Barrel in a coaxial

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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Centering the Barrel in a coaxial

Unread postAuthor: LikimysCrotchus5 » Mon Jan 28, 2008 12:07 am

Well the title basically says it.

I have some salvaged parts and i am making a coaxial with it. I finished it today, but there is one question that i have before finishing it. I used pressure rated poly pipe cut in half to center the barrel.

When you center the barrel, do you have to glue the things that are centering the barrel? Like epoxy it to the chamber? Or can i let friction hold it?

Would it those pieces blow out if i didnt secure it to the barrel?

Would i have to epoxy those pieces of poly pipe that are cut in half and centering the barrel to the chamber?

Thanks for the input.
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Unread postAuthor: hi » Mon Jan 28, 2008 12:19 am

i always glue mine...
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Unread postAuthor: LikimysCrotchus5 » Mon Jan 28, 2008 1:00 am

Ok thx i am just wondering because i have never built a coaxial b4 and i just wanted to make sure.

Now i gotta wait an extra day. :roll:
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Unread postAuthor: psycix » Mon Jan 28, 2008 4:42 am

I centered my barrel using pieces of an fitting wich is basically IDchamber->ODbarrel
I took this adapter and I splitted it up into 6 pieces, 3 of em were used to center the barrel, the other 3 were not used (coz air needs to flow past)

It looks like a nuclear sign :D
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Unread postAuthor: LikimysCrotchus5 » Mon Jan 28, 2008 3:26 pm

Is it glued though psycix?

EDIT: Well i tried my new coaxial today and it worked but i had a major leak in the front where my barrel sleeves through the bushing. It always seems that i get a leak whenever i sleeve the barrel through the bushing and this is a major problem for me that must be fixed.

How do you guys ensure that it doesnt leak through the bushing (female part)? Epoxy?

Since i am soo going to make my 4 inch piston, 3 inch porting cannon, i cannot manage to make mistakes and get leaks like this.

The problem may lie in when i am dremeling, or in my case using a drill with a dremel tool to sand away at the bump that blocks my barrel from going through the bushing. I may sometimes drill at the smooth part and it may cause there to be an uneven area that air may leak through.

I may have a solution. That would be to apply epoxy in the female part along with the primer and cement, so that it glues and the epoxy fills in the grooves.

So what do you guys think? Tell me what you do to sleeve a barrel down a bushing.
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Unread postAuthor: MaxuS the 2nd » Mon Jan 28, 2008 5:27 pm

LikimysCrotchus5 wrote:I may sometimes drill at the smooth part and it may cause there to be an uneven area that air may leak through.


That's your problem.
Just be more careful when sanding out the stops.
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Unread postAuthor: psycix » Wed Jan 30, 2008 3:28 pm

Yes, and no:
I glued the pieces of fitting to the barrel, but I didnt glue the center-keepers to the chamber.
Its not needed I think and kinda hard to do.
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Unread postAuthor: Gippeto » Sun Feb 03, 2008 2:12 am

I am planning something similar to what psycix referred to. My question is where to put the stabilizers? At the moment, I am thinking about 1/3 of chamber length away from the piston face.
Closer to the piston would yield better stability, but would it hurt flow? :?

And so, tongue in cheek, I ask you...What is your favorite position? :wink:
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Unread postAuthor: psycix » Sun Feb 03, 2008 6:19 pm

Gippeto wrote:I am planning something similar to what psycix referred to. My question is where to put the stabilizers? At the moment, I am thinking about 1/3 of chamber length away from the piston face.
Closer to the piston would yield better stability, but would it hurt flow? :?

And so, tongue in cheek, I ask you...What is your favorite position? :wink:

True, a stabilizer that is too close to the breech may constrict flow a little.

You should just find out what is the furthest point away from the breech where it still suppurts the barrel enough so it wont decenter.
1/3 may be a good option, but on long barrels it is too far away and on a short barrel it could be more back.

It also depends on the stiffness of your barrel pipe.
A SCH160 barrel wouldnt need much support if its just straight in. The thick walls wont bend much.
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Unread postAuthor: Gippeto » Sun Feb 03, 2008 11:08 pm

Thanks for the response. I'm using a 36" barrel, rigidity isn't too much of an issue, it's steel.

My project:
http://www.spudfiles.com/forums/high-pr ... 12803.html

Ok, can we call that 1 vote for 1/3 chamber length from the piston face?

Anyone else with a thought on this?





Edit: trying to fix link

It's working now.
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Last edited by Gippeto on Sun Feb 03, 2008 11:17 pm, edited 2 times in total.
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Unread postAuthor: LikimysCrotchus5 » Sun Feb 03, 2008 11:14 pm

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Unread postAuthor: psycix » Mon Feb 04, 2008 5:32 am

@ Gippeto:
Yup, 1/3 would be fine.
But dont make the stabilizer too flow constrictive.
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