SpudFiles

Hello, I'm designing a copper gun designed to shoot ball bearings..But I got a couple of questions...

1) Does chamber volume really matter? I mean, PSI is PSI..right? Does large chamber volume only matter if you want to shoot large projectiles or multiple projectiles? i want to make it as small as possible..Obviously just for looks..sort of like chaos's S400 Sniper.. But what is your opinion? I was thinking a chamber volume of around 50 cubic inches..Would that be enough to propel a .5" ball bearing around 450 fps..but a higher one would alwasy be better. I know at least one of you will suggest the GGDT...well I would use it...but my parents won't let me download it quite yet... So would a 50 cubic inch chamber be enough to propel a ball bearing at least 450 fps?

2) What kind of valve should I use?? I saw chaos's custom one..and I really like the look of that one....Anyone know how to build a valve like that?? Is it basically just a piston valve??

So thanks for the information guys....I know number one may seem like a stupid question....But I was just wondering about that..

You could make a piston valve or buy a Quick Exhaust Valve (QEV).

Chamber volume is importantish. If you can get high pressure you don't need such a large chamber.

What kind of pipe were you thinking of for the chamber and for the barrel?

Also, what kind of pressure can you get?

Well if your sacrificing volume, that means you need to increase the PSI and hope for the best with whatever valve you build.

that is an awsome gun!

K well my air compresor can only hold 125 psi..so i may need to use a large chamber..And as for the barrel and chamber material....I don't know yet..whatever my fleet farm has

For smaller launchers, I think chamber volume is less important than PSI (although it should be considered, read on)

Have a look at what I had done with my HVBB launcher back on spudtech.

Here's the pictures as the don't show in the archived thread:

ball barrings dont weigh enough to really matter. if you had a 1'' chamber that was 1 1/2'' long and a 1/2'' barrel that was 3 or 4 feet, you would have plently of power One thing that you may want to consider is that even if the chamber is rediculously big, it will still increase the muzzle volosity a little. so yes it important and at the same time it really isnt. on combustions it is really important to get it right, on pneumatics it really doesnt matter. you can have th C:B be 1:4 and it would be just fine, but a combustion like that would suck really bad.

K thanks jackssmirking revenge and hi..Guys.. I have a really basic and seemingly stupid question here... In this piston design...which has been the most helpful to me..I can't figure out why the equalization hole would be through the center of the piston!

http://www.advancedspuds.com/valve2.htm

Okay sorry for the stupid question.....I've used search, both on this site and on the internet...Okay here goes..

1) So that fitting that is in the lower left- the one that looks like a reducer coupling.that is connected to the chamber...And then the upper part of the T goes to the barrel correct?

2) One more thing- I just plain forgot something..kind of embarrasing...In order for the piston to seal.....the equalization hole would have to be sealed for a little correct?? How would I do that?? Or would it provide sufficient pressure...Just by making the equalization hole small enough?? Or should I make some sort of valve??

K so sorry for all of these stupid questions...I just need this one little more bit of information to really get this concept into my head..

If your piston fits tight enough in the chamber (assuming a barrel sealer where the piston face seals against the breech end of the barrel, not a chamber sealer) you won't need o-rings or an equalisation hole.

i agree with jack, i dont have o rings or equlization holes on mine and they work. also, the equilization hole doesnt have to be in the center, it can be a narrow groove on the side.

it would be impossible to be right in the center because thats where the the bolt for the sealing face goes.

The reason it runs through th centr is because it's a chamber sealer. Look at the animation at the boottom of the page.