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I need some plans....!

Posted: Wed Oct 08, 2008 7:22 am
by elad311
I got a new schrader valve and a pump, so I thought: :idea:
'Maybe I'll build a Pneumatic launcher'
But I don't know how, I need plans for one that is
simple, cheap, powerful and easy to make! :)

O, and, If anyone have plans for a good pump, I need it
too, because my pump not SO good. :?

Anyone?

Posted: Wed Oct 08, 2008 7:46 am
by Ragnarok
Sorry, for liability and safety reasons, we don't hand out plans, else idiots can build them all too easily, and then use them irresponsibly.

There is more than enough information around the site for you to work it out though. We find that people that have worked it out and understand their launchers are much more likely to be sensible, safe and careful with them - not to mention more satisfied with their work.

Might I suggest that your first port of call is the SpudWiki, which is packed with information. You can find the link along the top of the page towards the right.

Posted: Wed Oct 08, 2008 10:15 am
by jrrdw
Ragnarok wrote:Sorry, for liability and safety reasons, we don't hand out plans, else idiots can build them all too easily, and then use them irresponsibly.

There is more than enough information around the site for you to work it out though. We find that people that have worked it out and understand their launchers are much more likely to be sensible, safe and careful with them - not to mention more satisfied with their work.

Might I suggest that your first port of call is the SpudWiki, which is packed with information. You can find the link along the top of the page towards the right.
Ditto!

Thanks Ragnarok, now the mods don't have to type it out, or anybody else.

Search the showcase sections, there you can find plenty of study meterails to work from.

Welcome to Spudfiles..... :D

Posted: Wed Oct 08, 2008 4:27 pm
by FishBoy
while you're searching, I would suggest searching pressure rated parts in the wiki, and modded sprinkler valves

Posted: Wed Oct 08, 2008 6:47 pm
by Hydra
Some of my designs are based off a couple of guns in the pnuematic showcase.
GO look in the showcase, draw some designs and add a couple of tweaks (ie, Add a stock etc)

Posted: Wed Oct 08, 2008 11:26 pm
by MrCrowley
Step 1: Read up on the operation and principles of pneumatic cannons from the Spudwiki:
http://www.spudfiles.com/spud_wiki/index.php/Main_Page

2) Search through the Pneumatic Cannon Showcase section, find a design you like and either hand draw or use MSPaint to come up with a design of your own taking into account what valve you will use, main projectile and pressure. Then you can decide what chamber and barrel size you'll need.

I.E, if you want a decent one shot paintball cannon with an operating pressure of 60-120psi, you'll probably use a 1" sprinkler valve pneumatically modded, a 3/4" PVC barrel and a foot long 2" chamber.

3) Read this and make sure you understand it, print if required:
http://www.spudfiles.com/spud_wiki/inde ... sure_rated

4) Go to Home Depot (if you are in America) and buy the required materials, lay the parts out on the floor in shape of your cannon at the shop to make sure you have everything and all the right parts.

5) Find out how to use PVC primer and solvent properly if you do not already know.

6) Take your time constructing the cannon and don't take any shortcuts.


This could take anywhere between a week and a month or two to complete.

Posted: Thu Oct 09, 2008 8:22 am
by elad311
Tnx, MrCrowley, but I only found the glue 'AkFix',
can I use a hot glue gun the gkue the parts?

Posted: Thu Oct 09, 2008 8:32 am
by grumpy
elad311 wrote:Tnx, MrCrowley, but I only found the glue 'AkFix',
can I use a hot glue gun the gkue the parts?
first please type words so we can understand, and if you are asking if you can use hot glue, the ansewer is no it will not hold pressure. i,m sure you don't want you launcher flying apart when you put pressure in it.

Posted: Thu Oct 09, 2008 9:06 am
by Hotwired
That's not strictly true.

One of my first spudguns (didn't fire potato but thats irrelevant) used a chamber and a water hose pistol valve held together by hot melt glue.

It was not however a secure join despite both parts overlapping and being slathered with the stuff. Eventually the 100psi I was putting in would either from the start or after a few pressurisations, force its way out causing ballooning or leaks where it had forced the rubbery glue off the surface it was on to make a gap to escape though.

It just will not hold pressure properly as it's not strong and adhesive enough to deal with the force.

Posted: Thu Oct 09, 2008 9:44 am
by grumpy
either way i would not use hot glue and would not recomend anyone else use it either.

Posted: Thu Oct 09, 2008 10:59 am
by elad311
Well, Those are my plans for my first pneumatic cannon:

Image

Well, do you think It's good, Will it be powerful?

Posted: Thu Oct 09, 2008 11:37 am
by jimmy101
The basic layout is OK. The chamber is 2" diameter by one foot long? The barrel is 3/4" D by 27.6" (70cm) L. The C:B ratio is 3.1:1, so the chamber length could be cut in half with only minor affect on the gun's performance.

GGDT says that for a 15g round, assuming a 50mS valve opening time, the muzzle velocity would be about 270 FPS. The actual valve opening time will have a large affect on the gun's performance. (You'll get ~340 FPS if the valve opens in 20mS.) Ball valves and un-modified sprinkler valves open pretty slowly which is why the predicted performance isn't all that spectacular.

I would move the pressure gauge to the fitting between the chamber and valve. It'll be safer there and less likely to get banged up as you handle the gun. And, the double thickness (pipe and fitting) will make for a stronger connection that is less likely to leak. I would also put the fill fitting near the gauge.