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First Gun Build

Posted: Sun Jan 31, 2010 8:32 pm
by the_shadows
I'm a complete beginner and this is my first build. I haven't gotten a chance to test it yet. It's a 3/4" pvc pipe for my barrel, 2ft. 2" pvc for the tank and a 3/4" Watermaster sprinkler valve. Any ideas on psi to put into my tank?

Any comments and suggestions are more than welcomed.

Posted: Sun Jan 31, 2010 8:44 pm
by maverik94
Any ideas on psi to put into my tank?
That chamber doesn't look pressure rated.... is that sch 80 conduit? Because if so, it will burst with and serious pressure.

Posted: Sun Jan 31, 2010 8:48 pm
by the_shadows
It's a sch 40.

Posted: Sun Jan 31, 2010 8:50 pm
by deathbyDWV
Other than the pressure problem as mentioned above...

You could use alot longer of a barrel. Maybe 3 feet. Or if not a longer barrel then you could cut down the chamber to about one foot or less. You could cut it down alot and stilll get the same preformance.

Also some beginner advice... Schedule 40 isn't a pressure rating. That is just a wall thickness rating. You could make a whole new chamber for under ten bucks.

Posted: Sun Jan 31, 2010 8:56 pm
by Lockednloaded
your blow gun is backwards, and you ould use a much longer barrel. But I can tell you really did your research (if your chamber is pressure rated) most first cannons are DWV and ball valves, nothing against those kinds of cannons, but with a little more research, anyone can build a great cannon

Posted: Sun Jan 31, 2010 8:59 pm
by deathbyDWV
Lockednloaded wrote:your blow gun is backwards
It will still work that way but will slightly decrease preformance.

Posted: Sun Jan 31, 2010 9:02 pm
by Lockednloaded
It will still work that way but will slightly decrease preformance.
And blowguns usually leak when backwards, I've had one pilot the sprinkler valve unexpectedly before, they aren't meant to take pressure from that side.

Posted: Sun Jan 31, 2010 9:06 pm
by the_shadows
I should be able to get at least 100psi in the tank don't you think? I'm not intending for this gun to be very high powered, just a start or basis for future reference.

With the blowgun I thought I had it backwards but should still do the job wont it?

Posted: Sun Jan 31, 2010 9:07 pm
by deathbyDWV
It must just be the brand... I had one on an old bbmg up to 100psi and it didn't leak...

Posted: Sun Jan 31, 2010 9:51 pm
by spudtyrrant
I plugged the #'s into ggdt and if you increase your barrel length to 48 inches you will more than double performance, even tho this is just a practice gun i would still advise it

Posted: Sun Jan 31, 2010 11:59 pm
by MrCrowley
Your chamber should be as long as your barrel is at the moment and your barrel should be at least as long as your chamber is at the moment. Apart from that, nice build, swap around the blowgun, get a longer barrel and have fun :)

Posted: Mon Feb 01, 2010 12:14 am
by the_shadows
spudtyrrant wrote:I plugged the #'s into ggdt and if you increase your barrel length to 48 inches you will more than double performance, even tho this is just a practice gun i would still advise it
Thanks, I'll remember that when I cut my new barrel.

Posted: Tue Feb 02, 2010 12:08 pm
by the_shadows
What does it mean if my tank won't hold over 40psi when the day before I had up to 60psi?? It holds 40psi without any problem but anymore and wont increase. I can't hear any leaks but thinking there might be one where have blowgun attached.

Posted: Tue Feb 02, 2010 12:11 pm
by MrCrowley
the_shadows wrote:What does it mean if my tank won't hold over 40psi when the day before I had up to 60psi?? It holds 40psi without any problem but anymore and wont increase. I can't hear any leaks but thinking there might be one where have blowgun attached.
Submerge it in a bath and you'll find the leaks. Personally I use an empty spray bottle and fill it with soapy water, works great. Spraying on just plain water wont work as wlel.

Posted: Tue Feb 02, 2010 12:12 pm
by Gun Freak
It must be your comporessor. That wouldn't have anything to do with your gun or a leak if you can't hear it.