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 75 users online :: 4 registered, 0 hidden and 71 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

3/4" Copper Full/Semi-auto

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

3/4" Copper Full/Semi-auto

Unread postAuthor: skyjive » Mon Dec 22, 2008 10:56 am

This is my second attempt at an automatic design, the first was cylinder-actuated (its posted here somewhere) and was basically a failure due to a glacial ROF. This design uses a blow-forward bolt instead. Lets start things off with a firing video, five shots at about 70 psi into an old trashcan filled with old sheet to absorb impacts. Once the covering paper is destroyed its kinda hard to see the follow-up shots. This video is with the semi-auto/blowgun attachment in place:

[youtube]http://www.youtube.com/watch?v=aSzRm33BU9g[/youtube]

The gun has 60" of 3/4" type L chamber and 51" of 3/4" type M barrel. The firing valve is a McMaster 3/" QEV. The gun can be filled through either a Quick-Disconnect setup or a shrader valve for use with CO2 canisters or bike pumps (the former for rapid fire, the latter so I can test it without using up gas). The QEV can be piloted either by a blowgun or a 70 psi pop-off valve, allowing semi or full auto firing characteristics. The rate of fire at full auto is about 1.5 rps, slower with semi because the blowgun drops the pressure lower after firing, requiring longer refill time. The magazine is made of wood and can hold about 15 rounds. The ammo in the video is simply dowel sections wrapped in duct tape, but also usable in this gun are steel-tipped darts (not suitable for firing in my basement into a target 3 feet away!). Why not go outside, you ask?
Image

Some pics:

Image
(almost) the entire gun

Image
Looking down the barrel. The magazine is offset to one side to allow a clear(ish) line of sight and for better support.

Image
The blow forward bolt housing and feed tray (shown without magazine obviously)

Image
Bolt open

Image
Bolt closed

Image
From top: a ruler for scale, a 3/4" steel-tip dart, a shell from the original shell-ejecting design (couldn't make it happen, unfortunately), the blow-forward bolt housing, and the bolt itself.

And finally a video of a couple dry fires to show the bolt operating (yes it can shoot faster):

[youtube]http://www.youtube.com/watch?v=w1NME5XnuCY[/youtube]
  • 0

User avatar
skyjive
Master Sergeant
Master Sergeant
 
Posts: 163
Joined: Mon May 26, 2008 3:52 pm
Reputation: 0

Unread postAuthor: starman » Mon Dec 22, 2008 11:14 am

It won't win any beauty contests but I like your ingenuity on the thing.

Where are you located, getting that much snow?
  • 0

User avatar
starman
Donating Moderator
Donating Moderator
 
Posts: 3041
Joined: Wed Dec 12, 2007 12:45 am
Location: Simpsonville, SC
Reputation: 0

Unread postAuthor: ALIHISGREAT » Mon Dec 22, 2008 11:33 am

the chamber shape is unique! :D

but kudos for the 'semi-auto' :thumbleft:
  • 0

<a href="http://www.bungie.net/stats/halo3/default.aspx?player=ALI H IS GREAT"><img src="http://www.bungie.net/card/halo3/ALI H IS GREAT.ashx"></a>
Image
User avatar
ALIHISGREAT
Major General
Major General
 
Posts: 1779
Joined: Sat Aug 25, 2007 6:47 pm
Location: UK
Reputation: 0

Unread postAuthor: SP00K » Mon Dec 22, 2008 3:38 pm

Dang!!













You've got a lot of snow.
  • 0

We are all worms, but I do believe I am a glow worm.

~Winston Churchill~
User avatar
SP00K
2nd Lieutenant
2nd Lieutenant
 
Posts: 212
Joined: Wed Dec 03, 2008 4:20 pm
Location: Ohiya
Reputation: 0

Unread postAuthor: raptorforce » Mon Dec 22, 2008 5:43 pm

how does it work what makes the barrel move forward. i would have made mine but home depot was like "o no we have springs there over there but they werent there so i spent 15 minutes looking for something that wasnt there" very cool design maybe ill have mine working soon
  • 0


raptorforce
Sergeant First Class
Sergeant First Class
 
Posts: 137
Joined: Wed Nov 26, 2008 2:18 am
Reputation: 0

Unread postAuthor: Sticky_Tape » Mon Dec 22, 2008 5:45 pm

The air pressure pushes the BOLT forward.
  • 0

You can tell how awesome a cannon is by the pressure used.
http://www.spudfiles.com/forums/high-pr ... 12803.html
xnt rnm ne z ahtbg
User avatar
Sticky_Tape
Brigadier General
Brigadier General
 
Posts: 1175
Joined: Thu Jan 31, 2008 6:35 pm
Location: Sydney, Nova Scotia, Canada.
Reputation: 0

Unread postAuthor: raptorforce » Mon Dec 22, 2008 6:50 pm

Sticky_Tape wrote:The air pressure pushes the BOLT forward.

and this would be done by?
  • 0


raptorforce
Sergeant First Class
Sergeant First Class
 
Posts: 137
Joined: Wed Nov 26, 2008 2:18 am
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: Floyd » Mon Dec 22, 2008 7:32 pm

raptorforce wrote:
Sticky_Tape wrote:The air pressure pushes the BOLT forward.

and this would be done by?


http://www.spudfiles.com/forums/6mm-sem ... 10075.html

That link shows a variation of what is being done here.

@Skyjive
Looks great! How long was build/design time? A little polishing would make it better. Maybe get a smaller magazine. I'm liking the shape of the chamber. How is it to hold?
  • 0

User avatar
Floyd
Sergeant
Sergeant
 
Posts: 86
Joined: Thu Jul 10, 2008 6:42 pm
Reputation: 0

Unread postAuthor: skyjive » Mon Dec 22, 2008 7:48 pm

I live in New England, and we occasionally have massive winter blizzards which provide a convenient excuse to not do anything but build more weaponry. The chamber is shaped that way because my original design called for a vertical magazine under the barrel so I needed to get the chamber out of the way, and then I ran out of money so I couldn't redo it. I've been working on it for a couple weeks and am still fine-tuning it. I might reduce chamber volume for higher ROF and sometimes is mysteriously refuses to pilot, but it works pretty well.
  • 0

User avatar
skyjive
Master Sergeant
Master Sergeant
 
Posts: 163
Joined: Mon May 26, 2008 3:52 pm
Reputation: 0

Unread postAuthor: psycix » Tue Dec 23, 2008 6:16 pm

Nicely done on the blow forward bolt! :D
Cruelly done on the chamber shape! :shock:

If I understand it well, you just keep the air feed on while pilotting?
Note that the higher the air feed, the worse the pilotting thus the slower the opening time.
Though I think that the opening of bolt takes up enough time to compensate for the slow opening time of the valve.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Return to Pneumatic Cannon Database

Who is online

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'