SpudFiles

Here's my objective... to be able to fire, let's say a golf ball 1800 ft., but also be able to fire a tennis ball at only 40 mph. From one extreme to another. I would like to fire a golf ball, or projectile 1800 or so feet across the river for 'cool' points with the kids, but also be able to use this to 'throw' tennis balls/tee balls to my son for batting practice, who is 5 years old without knocking him completely out.

My plan... to use both chambers (600+ cu.in.) along with a 10 ft. 1.5 in barrel for my distance goal, but to use only one chamber (hence the ball valve on the end of chambers), one valve (sprinkler/piston) for launching tee balls for batting practice.

I've run numbers through GGDT and I'm real close to meeting both goals. I'm debating on using two 1" sprinkler valves as opposed to two 2" piston valves because I'm not sure if I can get the same consistency with the piston valves as in firing at the same time, firing at low pressures, etc... (I'm trying to build this with my 5 yr. old's safety in mind). I've built pistons before with success, they scare me just from the power alone. I've also built pneumatics with sprinkler valves. They are reliable, easier to make 'remote' (if not modded), just not as strong.

And in the design, I know the chambers are a little overkill from what I've found out in GGDT. One chamber can get me within a 100 feet of my distance goal. It seems balanced out having two chambers that will actually support sitting upright without having to hold. I could make them shorter to keep from wasting air that's left over, but why not, I've already got two 24 in. sections.

Specs...
Chamber: 2 x 4" dia. 24 in. long
Valves: 2 x Orbit 1" sprinkler valves OR two 2" piston valves
At this time no mods to sprinkler valves, to be able to wire up a remote)
Barrels: 1.5" x 10 ft. 2.5" x 24"
Pressures: Min. 15psi - Max. 150psi

Nothing has been glued yet. Nothing as far as a pilot has been put together for this, although I do have that figured out.

I'm looking for any ideas or suggestions before I glue everything together. Any changes to consider, which valves to use, etc...

Here's a couple of pics



And NOTE the 2" section of pipe toward the left side of pic... I'm a firm believer that shrapnel hurts. And you can ruin a $40 miter saw blade if you're not careful.

That definitly looks good! It should work out just fine Hope your kid likes it

wow big gun lol that things huge why not put some sort of regulater on it or something along those lines you could use a ball valve as you regualator half way for tenis ball full open for golf balls just a thought

i've got an irritol valve that has a limiting screw that limits how far the diaphragm opens and i use it a lot actually to power down my shots quite often if i need it. i think that this might be something that you could use.

http://www.irritrol.com/valves/valves.html

This is the link to irritol, I have a 200B series inch and a half and it is really a great valve and very easy to mod.

That looks good!

To make the sprinklers perform better, the tee wich joins the two sprinklers to the barrel should be sized up to barrel size.
Because even if you have 2x 1" sprinklers now everything still needs to go through ONE 1" pipe before it scales up.
Now it isnt THAT important since the sprinkler mode is less powerfull then the pistons, but it still is a thing to remember.

I hope that if you join the pistons together (the POWERFUL version) it will be done with a barrel-size joining tee, else it would be a true waste of power.

BigGrib... (LOL... in hopes my wife doesn't realize just how much I've already spent in PVC alone in the past month) It would be great to have one of Irritrol's valves, but the way I am, I couldn't buy a 1", or 1.5" valve at their good prices, I would have to buy the 2" valve just because its bigger, not because it might be necessary, but because its BIGGER. I follow the 'big is better' side of life. I've dropped a $100 already in this 'undecided' design, hence the reason for posting. I'm trying to nail down this thing. I craving the smell of glue..lol Its time to put it together.

psycix...

I hope that if you join the pistons together (the POWERFUL version) it will be done with a barrel-size joining tee, else it would be a true waste of power.

Most definitely, I will continue with two inch from the pistons. I have to put my hands on everything to 'see' it. If I decide to go with the pistons, its just another trip to Lowe's and $10 more. The 5 year old has seen this thing laying there in my shop already. He's chompin' at the bit to see it work.

fireman565 wrote:He's chompin' at the bit to see it work.

Hes not the only one waiting too see it working, we are too!

lol it looks good

I say make one 4" piston, and make a cheap $30 or $40 gun for your son later.

maybe you should try making on of the chambers smaller like 1" or 1.5" and put a 4" pipe over it so it is symmetrical. then you could use the big chamber or both of the chambers for your distance and your small chamer alone for your sons practice.

just an idea

MrCrowley wrote:I say make one 4" piston, and make a cheap $30 or $40 gun for your son later.

I tend to agree, A co-axial piston launcher with a full length chamber and golfball barrel would be ideal for distance - as to tennis ball launching, how about making a muzzle attachment similar to this' The flow restriction and short barrel will give you limited performance at low pressure good enough for your purposes.

this is referring to my post right above jsr's

<a href="http://s251.photobucket.com/albums/gg31 ... eridea.jpg" target="_blank"><img src="http://i251.photobucket.com/albums/gg31 ... eridea.jpg" border="0" alt="chamber idea"></a>

should make more sense now (ms paint is annoying!)