SpudFiles

OK, so I already have a perdy sweet combustion cannon..my "salad shooter", and then I stumbled onto this fine little site and did a little reading and got inspired to build a pneumatic. I went with copper and brass construction.....
How bout you all just look at the silly little paint drawing "not in scale" and let me have it.....

the ammo used on the can was one shot of a foam ear plug..shown in the photo... this monstrosity kinda scares me a lil..
this shot was at about 110psi. I'm sure this gun is well capable of much higher pressures. except for the piston possibly..wich is on its first rebuild already, what do ya think?

Wow that looks great. Damn those copper guns are shiny...

aq

One of the better first pneumatics I've seen, well done It seems a shame to stick to 110 psi though, it can probably take 250 psi easily.

What's your piston made out of? If it's not a 100% fit in the tube it travels in then there's no need for equalisation holes, though it was a good idea to use the zerk as a non-return valve

ya I was perty proud of the zerk idea..accually I modded the zerk by grinding a tiny bit of the end of the threaded side and pulling out the spring. Then carefully not to loose the tiny little ball I put it in a vice and Tig welded the back in a couple spots to keep the ball from coming out. Before the zerk, my blow gun wouldn't even trigger it, I had to use the ball valve. The piston is accually a prime "junk drawer" find. Its a hard rubber thing that is designed to go into an empty car lighter plug in. I lathed it to perfection on a dremel sanding drum mandrel, and filled it with clear epoxy. Is this thing legal by the way??? I hope so...hehe
a few more things to do to it.....not really done yet. still need to put the bolt action sleeve on it, a screw together grip that will cover the blow gun and attach it to the chamber, and some sort of an attachment for the fore grip to the barrel for a little better rigidity. still thinking of more mods...but so far....it works..so YAY, thanx for your compliment by the way

Is this thing legal by the way?

Depends where you live, it's fine in the US for example but in the UK legality would be questionable at best.

Regarding the piston, not that it only has to move back 0.125" for maximum performance, so if you fill in the extra space you'll cut down on your pilot volume and increase efficiency.

wow that looks pretty kool. Im amazed on how people can build pistons sooo much better then me, (sigh)

That truly is beast, especially for your first gun. I like how it can be held like a real gun, and I like the fact that you didn't ask a bunch of dumbassd questions before you built. I'm assuming you've soldered before?
you defiantly get a cookie or 2.

lol ^, the pope rocks

Really?!, it only has to move an 1/8 of an inch? Wow, right now I bet it travels a good inch or so. beating the S#*t out of my piston pointlessly.
I see what you mean about pilot volume. The less volume there is behind the piston the less "air spring" there will be when the pilot is exausted, probably pulling back on the piston more sharply. I will have to mold some of my putty epoxy into a removable piece with a port through the center to fill the space up, then cut a new bumper, and get that piston travel dealt with. The thing already suprises me with its power, I wonder how much crazier it will get when it is all tuned up.

lockmanslammin wrote:Really?!, it only has to move an 1/8 of an inch?

For maximum efficiency, the piston only has to move back 1/4 of the barrel diameter, we call this the d/4 rule - the math is worked out here if you're interested.

It's good to see you appreciate the value of efficiency

jackssmirkingrevenge wrote:It's good to see you appreciate the value of efficiency

I would normally recommend more than the d/4 rule, because of potential piston bounce, and just to be sure really.

Barrel sealers need a bit more distance again because flow can only come from below (above/theside/whereever).

how long is your barrel? I would like to see a cool breech load on that, it would totally make that launcher bad ass

Ragnarok wrote:I would normally recommend more than the d/4 rule, because of potential piston bounce, and just to be sure really.

Hence the rule being qualified

Barrel sealers need a bit more distance again because flow can only come from below (above/theside/whereever).

But in this case, the piston doesn't sit in the tee itself.