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Blowgun on mini steel 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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Unread postAuthor: pizlo » Sun Mar 16, 2008 6:43 pm

Counterstriker wrote:Another question, I was going to order a shrader valve off of BCARMS because all the shraders around here are the kind that you use a nut to tighten it down. But it says only good up to 150 psi.. I plan on using my mini coaxial to.. 200-300 psi. Btw, the barrel is gonna be 3/8, I have to buy more epoxy to keep in in place in the chamber..


The schrader will be just fine, but epoxying a barrel into a coax WILL NOT! There is no way in hell you'll ever get it strait enough, it needs to be perfect, I'm making a mini steel barrel sealer so I know.
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Unread postAuthor: Counterstriker » Sun Mar 16, 2008 6:46 pm

Then how can I make it straight?
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Unread postAuthor: pizlo » Sun Mar 16, 2008 7:18 pm

A reducer from the chamber to the barrel width. or a bushing, same thing.
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Unread postAuthor: kablooie » Sun Mar 16, 2008 7:31 pm

I am making a mini coaxial almost identical to yours, only breech loading (if it works). What I am wondering is if the steel nipple it looks like your using has a little ridge on the inside that looks like some kind of seam. Will this affect the Piston's sealing/movement?

For epoxying the barrel, I assume you mean into the reducer fitting at the front of the gun, and I don't understand why, if you have the rest of the gun put together, you couldn't just fit the barrel in with the correct barrel supports. This would be after you put the epoxy in and before it dried, so it would dry in the correct position. I have zero experience with epoxy however, and this is just an idea (and my plan, until now).

Edit: I assumed the brakeline was not in the right size for iron fittings, and that you would use the closest possible fitting and then epoxy the barrel into that.
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Unread postAuthor: bigbob12345 » Sun Mar 16, 2008 7:44 pm

potatoflinger wrote:
bigbob12345 wrote:And if it does fail then all that will happen is airr will rush out of it

Not true, if it fails it will also trigger the gun, which could wind up being a big problem :shock:


Well shouldnt your gun be pointed in a safe direction so it wont matter.

And counterstricker:looks good so far.
i love how you take a vid instead of a bunch of pics.
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Unread postAuthor: Counterstriker » Sun Mar 16, 2008 8:10 pm

kablooie wrote:I am making a mini coaxial almost identical to yours, only breech loading (if it works). What I am wondering is if the steel nipple it looks like your using has a little ridge on the inside that looks like some kind of seam. Will this affect the Piston's sealing/movement?

For epoxying the barrel, I assume you mean into the reducer fitting at the front of the gun, and I don't understand why, if you have the rest of the gun put together, you couldn't just fit the barrel in with the correct barrel supports. This would be after you put the epoxy in and before it dried, so it would dry in the correct position. I have zero experience with epoxy however, and this is just an idea (and my plan, until now).

Edit: I assumed the brakeline was not in the right size for iron fittings, and that you would use the closest possible fitting and then epoxy the barrel into that.


I know of that rigged line.. If you cast an epoxy piston inside of a smaller nipple (that has the same line inside) it should just slide in(match the knotch up).. it won't matter too much because you want some air to go around the piston to fill the chamber

~Counterstriker :D
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Last edited by Counterstriker on Sun Mar 16, 2008 8:20 pm, edited 1 time in total.
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Unread postAuthor: Counterstriker » Sun Mar 16, 2008 8:17 pm

pizlo wrote:
Counterstriker wrote:Another question, I was going to order a shrader valve off of BCARMS because all the shraders around here are the kind that you use a nut to tighten it down. But it says only good up to 150 psi.. I plan on using my mini coaxial to.. 200-300 psi. Btw, the barrel is gonna be 3/8, I have to buy more epoxy to keep in in place in the chamber..


The schrader will be just fine, but epoxying a barrel into a coax WILL NOT! There is no way in hell you'll ever get it strait enough, it needs to be perfect, I'm making a mini steel barrel sealer so I know.


The reason I wanted to epoxy it is because I am using galvanized steel, which makes me have to use galvanized steel reducers.. they do sell steel reducers for 3/8" but its threaded and the barrel is copper, So I guess I would need to epoxy it.. And is there any thing I can use to stabalize the barrel inside the chamber?
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Unread postAuthor: kablooie » Sun Mar 16, 2008 8:21 pm

Alright, thanks. Oh, and by smaller I assume you mean shorter, not smaller in diameter. I look forward to seeing the finished product!
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Unread postAuthor: Counterstriker » Sun Mar 16, 2008 8:25 pm

kablooie wrote:Alright, thanks. Oh, and by smaller I assume you mean shorter, not smaller in diameter. I look forward to seeing the finished product!


Yah shorter, Even if its not to snug you can sand it to fit. Thanks! I am eager to see yours also.

P.S. be sure to lube the pipe before you cast the piston.
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Unread postAuthor: Daegurth » Mon Mar 17, 2008 3:50 am

if you're worried about the schrader, take out the core and use a check valve instead. i intend to on my next project (first pneumatic, similar to copperhead prime), it's best to be on the safe side. remember with a piston, if the fill valve goes, it could fire the cannon- depending on how well your piston seals.
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Unread postAuthor: Counterstriker » Mon Mar 17, 2008 10:40 am

Daegurth wrote:if you're worried about the schrader, take out the core and use a check valve instead. i intend to on my next project (first pneumatic, similar to copperhead prime), it's best to be on the safe side. remember with a piston, if the fill valve goes, it could fire the cannon- depending on how well your piston seals.


Thanks but I am gonna stick with the schrader. Sorry I gotta run I am at school..... :roll:
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Unread postAuthor: Counterstriker » Tue Mar 18, 2008 5:39 pm

Well, as you know I decided to go with the 3/4 chamber, But when casting the piston on another (shorter) nipple it got stuck because of the galvanized steel and all its ripples. So my question is. Is PVC 3/4" the same as a galvanized steel 3/4" nipple? I am gonna cast the piston on the pvc cause its smoother. I would rather have it big then small, so atleast I can sand it..

Thanks!
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Unread postAuthor: bigbob12345 » Tue Mar 18, 2008 6:06 pm

The fit is close but not the exact same i think it is smaller but Im not sure.
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Unread postAuthor: Counterstriker » Tue Mar 18, 2008 6:25 pm

bigbob12345 wrote:The fit is close but not the exact same i think it is smaller but Im not sure.


Well I guess I will just use it, then add electrical tape.
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Unread postAuthor: pizlo » Tue Mar 18, 2008 7:45 pm

Counterstriker wrote:
pizlo wrote:
Counterstriker wrote:Another question, I was going to order a shrader valve off of BCARMS because all the shraders around here are the kind that you use a nut to tighten it down. But it says only good up to 150 psi.. I plan on using my mini coaxial to.. 200-300 psi. Btw, the barrel is gonna be 3/8, I have to buy more epoxy to keep in in place in the chamber..


The schrader will be just fine, but epoxying a barrel into a coax WILL NOT! There is no way in hell you'll ever get it strait enough, it needs to be perfect, I'm making a mini steel barrel sealer so I know.


The reason I wanted to epoxy it is because I am using galvanized steel, which makes me have to use galvanized steel reducers.. they do sell steel reducers for 3/8" but its threaded and the barrel is copper, So I guess I would need to epoxy it.. And is there any thing I can use to stabalize the barrel inside the chamber?


Hmm If you want to know what I think you should use a small diameter pipe that is NOT the barrel for the piston to seal on, then epoxy your barrel into that. I'm using A 3/4 iron T and have a 3/4 threaded to female adapter with lathed down half inch pvc going through to the piston face.
I can then put in a 3/4 to 1/2 inch bushing and put in my barrel(s).
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