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 83 users online :: 3 registered, 0 hidden and 80 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

The Hammer Shotgun

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
Sponsored 
  • Author
    Message

Unread postAuthor: jackssmirkingrevenge » Thu Feb 21, 2008 11:13 pm

I don't claim to have any original ideas, flip through
Google<sup>TM</sup> patent search and you'll know what I mean. I think the skill lies in first of all recognising existing concepts that can be applied to spudguns, and secondly having the material know-how to be able to flesh out your designs.
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24411
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 77

Unread postAuthor: Davidvaini » Fri Feb 22, 2008 12:06 am

I've already been a step ahead of JSR.. actually a few steps... I'm talking about baking a cake of course....
  • 0

User avatar
Davidvaini
Major General
Major General
 
Posts: 1315
Joined: Tue May 29, 2007 8:58 pm
Reputation: 0

Unread postAuthor: Ragnarok » Fri Feb 22, 2008 4:29 am

jackssmirkingrevenge wrote:To what extend this idea actually does this remains to be quantified.

One problem that needs to be addressed is the large pilot volume that is required.

Now, here that won't limit opening time badly, but the further a piston moves back, the more energy it takes out of the chamber, which could be a significant reduction in a small chamber volume like this one.
  • 0

Does that thing kinda look like a big cat to you?
User avatar
Ragnarok
Chief of Staff
Chief of Staff
 
Posts: 5366
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 10

Unread postAuthor: Novacastrian » Fri Feb 22, 2008 5:59 am

Here is the only pic that wanted to work of the new piston.
Image
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Fri Feb 22, 2008 6:04 am

The further a piston moves back, the more energy it takes out of the chamber, which could be a significant reduction in a small chamber volume like this one.


That is a factor but it can easily be compensated for in this case by adding an inch or so to the chamber volume, no big deal.

Nova, that's exactly how I had pictured it originally :) can't wait to see it in action :D
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24411
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 77

Unread postAuthor: Novacastrian » Wed Feb 27, 2008 3:18 am

Here i go with the vids, the first shows activation. However i am not sure that the frames portray it well. The pistons travel backwards and forwards very fast, and reseats itself. The other vids are self explanatory.
<a href="http://www.youtube.com/watch?v=J1S6ePYY03c&feature=user#">Piston</a>

<a href="http://www.youtube.com/watch?v=q3Tuu4h8now&feature=user#">Paint can</a>
<a href="http://www.youtube.com/user/TyaxComp">Water Bottle</a>
<a href="http://www.youtube.com/watch?v=h77tX1xs8GM&feature=user#">10mm thick acrylic</a>
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Wed Feb 27, 2008 3:30 am

yay! great stuff :D

So you're saying that the piston travels all the way to the end of the chamber, hits the endcap and bounces back?
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24411
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 77

Sponsored

Sponsor
 


Unread postAuthor: Novacastrian » Wed Feb 27, 2008 3:37 am

jackssmirkingrevenge wrote:So you're saying that the piston travels all the way to the end of the chamber, hits the endcap and bounces back?


That's it, the big or back portion bounces on acetal to acetal, the middle portion bounces metal on polyurethane, about as hard as a rubber band.
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Wed Feb 27, 2008 3:50 am

Interesting, perhaps a larger chamber would leave the pressure on firing higher for longer, dampening the bounce. What pressure were you firing at?
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24411
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 77

Unread postAuthor: Novacastrian » Wed Feb 27, 2008 4:02 am

~100psi, i am confident that the projectile has left the barrel before the piston bounces back, plus as the pressure leaves the pilot and chamber at the same time, i am lead to think that if there where still pressure in the chamber the piston would not bounce back "at all". It is a fairly large pilot for the size of cannon. Nuff talk, i'll have to wait and do a comparative test after i get a chrony :wink:
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Wed Feb 27, 2008 4:06 am

Only 100psi?

*cough*shockpump*choke*itcanprobablytake200psi*splutter*smallerlauncherslovehigherpressure*bark*

Anyone got a throat lozenge? :D
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24411
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 77

Unread postAuthor: Novacastrian » Wed Feb 27, 2008 4:11 am

jackssmirkingrevenge wrote:Only 100psi?

*cough*shockpump*choke*itcanprobablytake200psi*splutter*smallerlauncherslovehigherpressure*bark*

Anyone got a throat lozenge? :D


Fair suck of the sav! One knows that higher pressure yields more power :D I would like to get an efficient design built before i start pumping!! :P
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Unread postAuthor: Gippeto » Wed Feb 27, 2008 2:50 pm

That works slick!

I like it, I like it a lot. :D
  • 0

"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2420
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 16

Unread postAuthor: Novacastrian » Wed Feb 27, 2008 8:27 pm

Gippeto wrote:That works slick!

I like it, I like it a lot. :D


Thanks Gippeto :)
  • 0

America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Novacastrian
Major General
Major General
 
Posts: 1604
Joined: Sat Aug 11, 2007 6:59 pm
Reputation: 0

Previous

Return to Pneumatic Cannon Database

Who is online

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot]

Reputation System ©'