need spudgun help!

[Maverick]

Hi, I’m a brand new member to this site, and am really into potato guns and need some help from some you all. I have built many combustion type guns and always thought they were a lot of fun, until I heard about pneumatic guns. Now, I’m going to build one, but I need some help doing that. I have attached a link which shows my plan for the gun, but I will also walk you through my plans:

I’ll start out with a 2 ½ or 3 foot length of Sch80 (3 inch diameter) of PVC for the chamber. One end will be sealed with a 3 inch Sch80 end plug, and the other will have a 3 – 1 ½ inch reducer. From there, I’ll attach a 2 inch length of 1 ½ inch diameter Sch40 PVC, and then attach another reducer (1 ½ - ½) to the end of that. I’ll then take a 2 inch length of ½ inch diameter PVC and solvent weld the reducer and pipe together. From the end of that, I’ll solvent weld a threaded ½ inch PVC male adapter. Then I’ll take a threaded ½ inch brass ball valve and screw onto the PVC adapter. I will use another male adapter to screw into the opposite end of the valve, and then solvent weld my barrel (1/2 inch PVC or copper pipe) to the adapter.

Some of you may think that this is a dumb plan, and have much better ideas… if you do, please tell me what I should do differently! Any simpler way to make this thing would be great! Also, I have a few questions: Is there a special type of glue that exists that will strongly bond copper pipe and PVC? My other question is about the valves… what’s the best one to use? I have seen some people that have modified a sprinkler valve, but I went with a ball valve because it costs less and its simpler. Which should I use?

Any and all comments are more than welcome. Please reply and tell your ideas and thoughts. Thanks!

Here is a picture: http://img404.imageshack.us/img404/4007 ... gunwa1.jpg

[keep_it_real]

Put the schrader valve through the fitting and the pipe so its stronger. The CB (Chamber Barrel) ratio looks way off. Either make the barrel bigger or longer or the chamber smaller. If you can switch the ball valve out for a sprinkler valve and you'll be 10 times happier. Modding a sprinkler valve is really easy. There is a tutorial in the how-to section. Search for it.

[iPaintball]

You sould definately go with a modded sprinkler valve. You will achieve a much higher muzzle velocity and increased range like you wouldn't believe! Also, you might want to change it to an over/under design so it's more compact.

[sgort87]

I don't see why you need sch 80.

[super spuder]

use a piston valve, they are even better than sprinkler valves, and yea as sgort87 says you will probly not need sch 80 piping depending if you are going to be running allot of pressure (sch80 will hold over 200psi) i think

[goathunter]

The proportions of the barrel to chamber are all off.Use 2" pipe instead of 3",at that you a have a huge air chamber.Look in the Wiki section and learn about the basics.Good luck.