Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 56 users online :: 4 registered, 0 hidden and 52 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Cad drawing project (PCP airgun)

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
Sponsored 
  • Author
    Message

Cad drawing project (PCP airgun)

Unread postAuthor: Necrosis » Mon Oct 08, 2007 12:35 pm

I am looking for some help!

Mainly in valve choise.
And how to trigger this stuff.

This thread is also a container of stuff I am going to model.

I got my dad to agree to machine the needed stuff if I could draw a working model.

So off to solidworks I go!

(Sorry for the chaotic nature of this post, I am sure that it will get better)
  • 0

Attachments
barrel.png
It is the barrel.
barrel_cross_section.png
It's the barrel's cross section.
User avatar
Necrosis
2nd Lieutenant
2nd Lieutenant
 
Posts: 239
Joined: Tue Jul 03, 2007 10:03 am
Reputation: 0

Unread postAuthor: benstern » Mon Oct 08, 2007 2:30 pm

uh pneumatics usually don't have enough power to make use of rifling.
  • 0

User avatar
benstern
Donating Member
Donating Member
 
Posts: 909
Joined: Wed Sep 21, 2005 8:24 pm
Reputation: 0

Unread postAuthor: Brian the brain » Mon Oct 08, 2007 2:35 pm

excuse me?!?!?

he did overdo the number of turns on it though....
  • 0

Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
User avatar
Brian the brain
Moderator
Moderator
 
Posts: 3494
Joined: Mon Dec 05, 2005 2:06 am
Location: Holland
Country: Netherlands (nl)
Reputation: 29

Unread postAuthor: origin unknown » Mon Oct 08, 2007 2:46 pm

You are very lucky that your dad can machine things for you. If I were you, I would design something like a 40mm rifled PCP cannon with a CO2 fill system and a piston valve.
  • 0

Ecclesiastes 1:9 - What has been will be again, what has been done will be done again; there is nothing new under the sun.
User avatar
origin unknown
Colonel
Colonel
 
Posts: 533
Joined: Sat Apr 14, 2007 2:38 pm
Location: Searcy, Arkansas (college) and Memphis, TN (hometown)
Reputation: 0

Unread postAuthor: DYI » Mon Oct 08, 2007 3:04 pm

My only comment so far would be that the rifling is really overdone.

This looks like it could be a really interesting project. If you have the capabilities to machine complex parts, I would suggest a piston valve. If not, and you plan on using high pressures (as I hope you do), you could just use a pneumatically actuated or spring loaded ball valve. And don't use CO2, it's just a waste of power, unless you already have a CO2 fill setup.
  • 0

Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Unread postAuthor: benstern » Mon Oct 08, 2007 3:29 pm

I ment that pneumatic can't use rifling on metal of plastic ammo that fits tightly.
  • 0

User avatar
benstern
Donating Member
Donating Member
 
Posts: 909
Joined: Wed Sep 21, 2005 8:24 pm
Reputation: 0

Unread postAuthor: Necrosis » Mon Oct 08, 2007 3:49 pm

The rifling is indeed overdone, The power source will be compressed air, as we can get that for free, in 12 litre 200 bar packages*. :wink:

And yes the rifling is a bit overdone, But it's just a matter of typing let's say, 5 in stead of 20 in the box that says number of turns. :D

*that does not mean I will actually use those 200 bars, I will probably end up at a maximum of 50 bars using a reducer valve.
  • 0

User avatar
Necrosis
2nd Lieutenant
2nd Lieutenant
 
Posts: 239
Joined: Tue Jul 03, 2007 10:03 am
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: DYI » Mon Oct 08, 2007 3:55 pm

Even 50 bar is a respectable pressure, and air will certainly be more impressive than CO2 for that pressure. Just make sure that there isn't anything particularly flammable in the chamber or valve and you should be fine.

In my opinion, if you have the ability to, you might as well use the 200 bar. I've wanted to see a real high pressure cannon here for a while.
  • 0

Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
DYI
Lieutenant General
Lieutenant General
 
Posts: 2861
Joined: Sat Jul 07, 2007 8:18 pm
Location: The People's Republic of Canuckistan
Country: Turks and Caicos Islands (tc)
Reputation: 9

Unread postAuthor: jackssmirkingrevenge » Mon Oct 08, 2007 10:08 pm

Most PCPs use a hammer valve like this antique Girandoni:

Image

Modern designs haven't changed much, though they tend to use helical springs to hammer the valve. This flash demo or a pump-up pneumatic might also be helpfil ;)
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: Necrosis » Tue Oct 09, 2007 7:11 am

Just a quick question, doesn't CO2 turn liquid at 50 bars? or was that some other gas..
  • 0

User avatar
Necrosis
2nd Lieutenant
2nd Lieutenant
 
Posts: 239
Joined: Tue Jul 03, 2007 10:03 am
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Tue Oct 09, 2007 7:55 am

closer to 5 bar actually.
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: Necrosis » Tue Oct 09, 2007 9:08 am

That's what I meant. :oops:
  • 0

User avatar
Necrosis
2nd Lieutenant
2nd Lieutenant
 
Posts: 239
Joined: Tue Jul 03, 2007 10:03 am
Reputation: 0

Unread postAuthor: williamfeldmann » Tue Oct 09, 2007 12:18 pm

Yeah, I wish I could machine parts.

If you really have access to the machines and skilled labor, a piston valve would be one of the first things I'd make. Sure a piston is a piston but with the lathe you can make one hell of a nice fitting and performing piston.

I couldn't find any mention of what size you are making the barrel. What is the ammo of choice? The choice of ammo might make the decision on rifling easier (wadded marbles could user higher turn rate than say a spud or tennis balls.
  • 0

Trying to figure out how to make a SCUBA first stage regulator work for portable charging station. If only that pesky job thing didn't keep eating up all my time...

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." - Albert Einstein
User avatar
williamfeldmann
2nd Lieutenant
2nd Lieutenant
 
Posts: 216
Joined: Sun Sep 09, 2007 6:55 pm
Location: Ames. Iowa, middle of BFE
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Tue Oct 09, 2007 12:36 pm

Code: Select all
I couldn't find any mention of what size you are making the barrel. What is the ammo of choice?


For a small calibre there's a variety of black powder calibres (0.44 etc.) that would be ideal as ammunition would be easy to find and velocity from a long air rifle would be analogous in terms of velocity to a shorter BP pistol for which twist rate data is already available.
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: Necrosis » Tue Oct 09, 2007 1:42 pm

The caliber and ammo are still to be decided.
It's probably going to be a lead projectile, though.
  • 0

User avatar
Necrosis
2nd Lieutenant
2nd Lieutenant
 
Posts: 239
Joined: Tue Jul 03, 2007 10:03 am
Reputation: 0

Next

Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], Yahoo [Bot]

Reputation System ©'