Coax Question

[ShowNoMercy]

I have a few questions regarding the construction of a coax cannon.
1) Has anyone attempted to utilize more than one barrel inside the chamber?
2) Do I have to use a coupler and a bushing for the ends of the chamber or is there a way to use a bushing straight into the chamber?
3) If I were to build a coax with a 2" chamber, would a 1 " sprinkler valve be overkill?

Thanks

[mopherman]

(1) no, lack of proper fittings has prevented that.
(2) yes, you must use a coupler and bushing. Unless you can find a bushing that fits quite well.
(3) no i dont think it would be overkill. I think it would pilot quite well.

[Hotwired]

(1) It is possible with copper fittings - there are 22mm -> 2/3/4 x 8/10mm fittings
(2) You dont get (pressure rated) Reducing Couplers where you are?
(3) What mopher said

[spudgunnerwryyyyy]

1) dual barrels would require custom epoxy casting.
2) epoxy casting would work great
3) Pilot valve size is not a matter of over kill its more a matter of performance versus cost. But that would work great for that chamber.

[ShowNoMercy]

Has anyone heard of or used Starboard? I have a lot of it at work and I was wondering if anyone had used it in a spudgun before. Its made from recycled plastic and I can get it in 1/4 and 1/2 sheets, similar to plywood. So I am thinking of making a coax piston and bushings for the ends out of it.

[jackssmirkingrevenge]

1) dual barrels would require custom epoxy casting.

Indeed I often though about doing this but always found it better to just use a single large barrel and use a sabot to fire multiple projectiles.

[Lentamentalisk]

@hotwired
I think he is talking about a bushing, the ones that go inside the big pipe, not a reducing coupling, though it does seem more practical to use a reducing coupling, given that there are no bushings that actually fit in the pipe, since they have the same OD as the pipe, so require a coupler like he was talking about.

[Killjoy]

A 3"-2" bushing fits well in 4" pipe, I did that for an unfinshed coax and it worked great.

[frankrede]

I have a few questions regarding the construction of a coax cannon.
1) Has anyone attempted to utilize more than one barrel inside the chamber?
2) Do I have to use a coupler and a bushing for the ends of the chamber or is there a way to use a bushing straight into the chamber?
3) If I were to build a coax with a 2" chamber, would a 1 " sprinkler valve be overkill?

Thanks

I believe #1 has been done, I'm not sure though

[jackssmirkingrevenge]

I believe #1 has been done, I'm not sure though

luckythirteen on spudtech had made a twin-barrelled cloud but I don't remember anything larger.

[ShowNoMercy]

I think I am going to go for two barrels, probably the 1/2 inch CPVC stuff. Since I will be using a piece of plastic instead of bushings I can make however many barrels I want to, however I plan on using a 2inch pipe for the chamber, do you think that with two barrels in it the volume available may not be enough?

[jackssmirkingrevenge]

even if the barrel's o/d was 1 inch, having 2 barrels in a 2 inch chamber would still give you a C:B ratio greater than 1:1 if your barrel was as long as your chamber, so you should be fine.