Second Pneumatic Potato Gun

[Potato Demon]

Hello SpudFiles, I have made a second pneumatic spud gun. I just finished it a few hours ago and I need to let the cement dry for a full 24 hours before I shoot. Here are the specs: Modified sprinkler valve trigger, 2’ x 4” air tank, operates at 80 to 100 psi, unsuppressed the barrel is 2 feet long (in the picture the suppressor is on), all parts are either galvanized steel pipe, solid core schedule 40 pvc, or solid core schedule 40 abs (except part of the suppressor). I chose abs because it didn’t fail on my first pneumatic which operates at the same pressure. I’m not sure if the suppressor makes pneumatics quieter or not but it will probably make it more accurate. Oh and the barrel comes off if I get rid of that chunk of wood. I am hoping that I did a good job on that valve!

[hectmarr]

Looks great. When it is operational, it would be nice a little video to watch it shoot. regards

[Potato Demon]

Thanks, I just need to make it airtight and then I will be sure to record a video of it shooting. I did have some issues with it and I changed it slightly from the picture and I am roughly 90 percent finished. The whole thing cost about 50 or 60 dollars Canadian. I need to add a pressure gauge because the one on my bike pump broke... Thank goodness for thread tape!
Update: I ran into some problems with air leaking and stability so I dug out some jb weld and epoxy and connected some parts a bit better (NEVER USE HOT GLUE!) I did however leave some hot glue on the valve because it didn’t seem to be a problem there. I am hoping that it sets properly without me watching it tonight...

[Potato Demon]

I have run into a problem, the air is leaking I have mostly fixed but I will cover the entire area that is leaking (the 1.5” pipes on the air tank) in some of that putty stuff jb weld sells.

[jackssmirkingrevenge]

Note that the weak point is the shoulder that connects the barrel to the chamber, at the moment of firing the recoil puts a lot of stress on this part, so it's a good idea to put a strap at the point where your wooden spacer is.

Also, you will get better performance if you put your valve directly at the breech like this:

[Potato Demon]

Good idea! I will be sure to work on strengthening the back. The only problem is that everything is stuck together with jb weld now...

[wdr0]

i would guess your leaks come from pvc glued to abs. Most plumbing codes do not allow it even for non pressure drainage as it is not a secure joint. PVC and ABS will not properly solvent weld together. You will need to use all pvc or all abs with the glued joints.

[Potato Demon]

Actually it is not leaking there, it is leaking on the pvc to pvc part. I guess the threads are damaged or something. Oh well I guess it shouldn’t be too hard to fix. Actually if you use primer on the pvc and transition cement on the abs it will hold together; I know this because I did it on my first pneumatic.