Help with Gun.

[jmeyer1022]

I've been a fan of combustion launchers but I'm getting tired of buying propane and other propellants. Seeing as I already have a 135 Max PSI air compressor I figure I'd switch to pneumatic.

I'm Def going to go for a 2" sleeved barrel for golfballs. From what I've been reading a piston is a must for max potential. I'm just a bit confused with the build of it. I completely understand the idea of it problem I'm have is
How would You get a 2 inch barrel that far the chamber without it being all over or not properly sealed. Yes I've read diagrams and how to most get skimpy on detail. I'm use to Combustion launchers so please treat me as If I'm a newbie to these.

So far I'm looking at
http://www.instructables.com/id/Golfbal ... That-Shoo/

Except I'm not looking into the breech loader and I plant to sleeve the barrel since 1.5" PN12 is hard to come by.

Please let me know any info you need or ideas for a launcher of this sort.
I'm asking for harassment but please keep it to a minimum.

[MrCrowley]

BTW, I wrote that Instructable.

Can you rephrase your question?

How would You get a 2 inch barrel that far the chamber without it being all over or not properly sealed

I don't quite understand what you're getting at.

Oh and PN12 is an Australian/NZ plumbing pressure rating system. For the American equivilant, read this:
http://www.spudfiles.com/spud_wiki/inde ... _Rated_PVC

[starman]

I've been a fan of combustion launchers but I'm getting tired of buying propane and other propellants. Seeing as I already have a 135 Max PSI air compressor I figure I'd switch to pneumatic.

You're tired of buying $2.50 propane canisters of which if one is properly installed, can be expected to fuel the practical life of the launcher??? Your reasoning makes no sense whatsoever.

You've got a nice compressor and you want to build a big bore pneumatic. OK, now you'll be stuck shooting it at your house or lugging the compressor everywhere you shoot....and that will be where there's AC power available.

Not trying to dissuade you from building your pneumatic...just letting you know the realities of it. You can always incorporate a CO2 system to launch with instead of compressed air. Otherwise combustion is a better choice for portable big bore guns.

[MrCrowley]

Not trying to dissuade you from building your pneumatic...just letting you know the realities of it. You can always incorporate a CO2 system to launch with instead of compressed air. Otherwise combustion is a better choice for portable big bore guns.

I feel like you're a salesman trying to steal my customer

starman speaks the truth, but you may as well give pneumatics a go. They're a heap of fun.

[starman]

I feel like you're a salesman trying to steal my customer

Now would I do a thing like that.... 8) never.....

BTW Jmeyer, welcome to Spudfiles. As you might have picked up, Crowley leans pneumatic, I lean combustion...we both appreciate the inherent values of each platform.

[jackssmirkingrevenge]

Otherwise combustion is a better choice for portable big bore guns.

Fair enough, but if it's sheer, brute POWER you want...

[D_Hall]

Otherwise combustion is a better choice for portable big bore guns.

Fair enough, but if it's sheer, brute POWER you want...

...then you go with a powder gun.



Oh, wait... We're not supposed to talk about those. Let me restate...

If it's sheer, brute power you want....

...then you go with a hybrid.

8)

[starman]

Crowley, the salesmen have all gathered on Jmeyer's front lawn this morning...care to join us for tea?...

[jmeyer1022]

The canister does last a fairly long time but I use them for things other than launching So I guess I'll still be buying them. I guess what I'm looking for is a huge power at home, Yes I know limited room I got about an Acre of land and then a huge woods beyond me. My neighbor just loves it, often comes over and is just amazed by it.


MrCrowley I'm going to pick up the parts for the piston housing. I can't stand reading directions I'm hands on I got the idea for the most part if I run across any trouble I'll come to you. Thanks

I Had to edit after I saw the salesman on my lawn, gave me a solid laugh.. Also I live in New England region. It can get pretty cold, Propane def loses performance with even a slight change in weather aka 50 degrees Fahrenheit. I know the PSI rating drops based off temperature but will I still be able to shoot stuff at a lower PSI in the cold.

[jimmy101]

It can get pretty cold, Propane def loses performance with even a slight change in weather aka 50 degrees Fahrenheit. I know the PSI rating drops based off temperature but will I still be able to shoot stuff at a lower PSI in the cold.

A propane fueled combustion shouldn't loose any power in cold weather. Do you have a chamber fan? WIthout a fan, fuel mixing is noticably slower in cold weather than it is on a nice hot summer day. Poorly mixed fuel / air can cut the gun's performance by a huge amount, i.e., 90%.

Or, are you refering to using the propane in a pneumatic? If so, cold weather has a pretty large affect on the pressure in a propane tank. At 90F the propane tank is at about 150 PSIG. At 50F its only about 80 PSIG. (From the SpudWiki propane page.)

Back to jmeyer1022's original question, which nobody has really anwered yet.

I'm not a pneumo expert, but I believe the barrel is gotten into the chamber by Dremeling out the stop in the fitting so the barrel can slide through it. I believe some builders then add spacers between the barrel and the inside chamber wall to keep things properly centered and aligned.

[jmeyer1022]

I'm using a direct input of Berzomatic propane I was using a chamber fan until it stopped working after a few launches having trouble finding another one of size/support I had

[Gippeto]

That's the ticket. Dremel, file or turn the lip out.

For the record, I've only three pistons under my belt (only two of which used these "techniques"), and don't consider myself an expert, but principles are always principles.

Start square, stay square, and finish square.

A wrap of masking tape around the barrel, having the edges meet exactly, while the tape is flat and smooth, will aid in cutting the barrel square if you don't have the right tools to do it another way.

I also "fix" my piston in place (where I want it), and use it as a stop for the barrel. This also helps ensure that the piston will seat squarely on the barrel.

I then place peel and stick sandpaper on the piston and use it as a tool to sand the barrel face. Black marker on the barrel face shows any imperfections.

Using this series of "techniques", I've never had a problem getting a piston to seal the barrel. I use one layer of 1/16" neoprene gasket or diaphragm (fabric reinforced) material.

[jmeyer1022]

How much power does the piston add? I'm looking for power but nothing to insane if you get my drift. Crowley's cannon says 450 yards that's unreal
I'm looking for something between 225-300 yards is a piston a must for this? I plan on running at about 90-125 PSI

[MrCrowley]

300 yards probably could be done with a long (5' maybe) barrel, a decent sized chamber and a 1" sprinkler valve at 125pi. I'll run some figures in GGDT later, i've got school now.

[Gippeto]

Really, I can't say. I'm a cheap bastard, and won't fork out the $25 to buy a sprinkler.

But, I can build a piston valve for less, so why bother with them?

The general consensus on ball valves seems to be that they have poor performance in comparison to either.

I will recommend the piston valve anyway. If it performs better than you want, you can always shorten the barrel, reduce the chamber size, or simply use less pressure.