Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
Hello all! I've been chipping away at these cannons for a while and they're finally operational. I decided to stay away from pvc for my first cannons due to all the stories I hear about them failing, especially with pistons, plus all threaded fittings means it's much much easier to make modifications. Although they are both functional I still want to make changes and touch ups before a showcase post. I pretty much built them at the same time, as they are virtually the same design (piston valves) just different sizes. All critique welcome!
This is the 1.5" cannon. Barrel is not screwed in in the photo (1.5" sdr21 sleeved in sch80 pvc). First dry fire at only 50 psi was surprisingly loud, and it sounds really efficient. I plan on reducing the chamber size and adding barrel support.
GB cannon
Piston needs a minor fix as it seems I've got metal on metal near the sealing face so there's a tiny leak from that.
Piston for the 1.5" cannon
The filling and pilot station works well, although I would like to make it a bit more aesthetically pleasing. Some elbows might help for it to be more "in-line" but any recommendations would be great. Uses a standard modded sprinkler valve as a pilot.
Pilot/filling area
Here's the smaller cannon. It's got a .5" copper barrel, great for marbles, batteries and homemade darts. Will probably be ordering some ball bearings as well.
.5" cannon
The qev is probably overkill for the pilot, but with the length of hose I have I figured I'd be losing efficiency with just a blow gun pilot.
Filling/pilot/piston housing
As for changes to the .5" one I'd like to make a body for it, or at least somewhat of a clean looking housing. I also plan on making a breach for it but I have struggled to find many good breaches for .5" copper barrels.
Got some dry fire videos of both. Nice to see a little bit of kick in both the cannons. Would love to do some damage videos asap but probably can't for a while - I'm in a pretty dense city atm
Last edited by Trauts on Sun Mar 02, 2014 12:34 pm, edited 1 time in total.
It seems like the sprinkler valve top is leaking as I get past 50psi, a result of a weak top and cheap epoxy. I'm thinking one of two options...
1-lather on the rest of the epoxy I have over the top of the valve
Probably worth trying even if it is a waste of epoxy
2-move the qev from the smaller cannon to the bigger one
I have a 2"x1/4" reducing bushing kicking around so I could keep the pilot volume for the qev pretty small, but would I be losing too much efficiency in doing so?
Eliminating the sprinkler valve would up the max pressure for the set-up, but I'm mostly wondering if my qev solution will work, and at the same time I'd probably have to totally change the smaller cannon to be blow gun operated.
