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 63 users online :: 3 registered, 0 hidden and 60 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

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

The Team
Administrators
Global Moderators
global_moderators.png CS

The Guillotine

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

The Guillotine

Unread postAuthor: deusXmachina » Sun Apr 29, 2007 7:24 pm

The Guillotine

Image
Click for full album


Stats:

Chamber: 4" x 10' PVC 1510 cu in
Valve: Mk IV.5 Barrel-sealing 3" piston
Pilot: 1" modded sprinkler valve piloted by electrical 3/4" RainBird sprinkler valve
Pilot Volume: ~36 cu in
Barrels: 2.5" x 20' PVC 1180 cu in and 3" x 10' PVC 850 cu in
Operating Pressure: 40-100 psi
Ammo: Finned PVC rockets with metal tips
Stand: Bungee-dampened suspension system with boat winch to control elevation. This actually helps out tremendously when dealing with recoil (the muzzle energy is 4000 J at the LOW end) and after each shot it sways back and forth harmlessly, the bungees do a great job of absorbing the recoil. And a nice mahogany-cherry stain.

Performance: Maximum range of 1800 feet (conservative) at 70 psi using the 2.5" x 20' barrel. Ammo was 2' long .5" wide finned PVC rocket with metal pipe tip (using the electrical tape piston, which also broke the valve - see The Cannon Story). Without the taped piston, shots usually traveled about 1000 feet.

More Pictures:
Image

Image

Image


Image
This is the bulkhead, instituted starting with the Mk. IV valve to make the process of adjusting the inner sealing surface easier and just make the valve more accessible. This modular capability has helped SO much and has saved at least one rebuild, perhaps two.

http://s152.photobucket.com/albums/s161/deusXmachina_spuds/?action=view&current=DSCF1272.flv
Video: You can't see it, but you can probably hear the piston shattering the end of the valve.




Click here to view the rest of the album


The Cannon Story
What seems like an eternity ago, perhaps more like a year and a half, n00b and I started work on a large 3" porting piston cannon. We thought it would be a straightforward summer project. Two summers later, we're still straightening out bugs. But that's invention for you. Construction pretty much broke itself down into stages, the failure of each valve led to new innovations and different approaches.

Mk. I
Much of the cannon's bits were built at this stage. The 3" barrel, the chamber, the fill system, pilot (at the time just an electric 1" valve) all pretty much carried through the whole project. The compressor I had from a previous spudgun. Due to a lack of machining ability, we've always have trouble with two bits: The valve housing itself and the piston. We built it like a coax cannon with a Wye as the chamber, which extened into the rest of the chamber. We used a 3" endcap with neoprene surface as the piston. Mk. I flat out didn't seal.

Mk. II
Essentially the same design, used the same piston from before. Sealed to 10 psi on a good day, but leaked so terribly it essentially didn't seal at all. We made the mistake of painting this one before testing it. D'oh. It ended up as a combustion cannon :lol:.

Mk. III
This valve we experimented with interior sealing surfaces (on the pipe exposed to the piston) This worked, actually very well, but we never glued down the sealing surface, and it kept shooting it after each shot, and each shot had to be completely reset. So we tried gluing it down. It stopped sealing. I tried to rebuild it by chiseling out the front end, ended up smashing the whole front end. We cut off the back half of it and used it on the Mk. IV.

Mk. IV
This was a radically different approach to valves from what we had been taking. I chose to make the entire front half removable, which added to the cost and complexity of the valve, but it saved far more effort in the long run. It allowed us to properly make a reverse sealing surface, which worked. Also, in this valve the pipe goes halfway through the opening of the Wye, allowing far greater airflow. We made a new piston using a coupler, LOTS of sanding, a 4" grind plate for angle cutters, a neoprene pot holder, and a pool noodle bumper. This valve worked through all pressure ranges, was repeatable, it was a godsend compared to what we were used to. We build the gantry, which gave the cannon its name, because it looks like an honest to god guillotine, and started to paint the valve. Crap...we might jinx it....so we decided to only paint half. In hindsite, even that was too much. This is also when we built the 20' barrel. We were getting 1000 feet consistantly, but the actuation time on the valve was HORRIBLE. It would vent out of the pilot for 1-2 seconds before triggering the piston. By then, only half the pressure made it out the barrel.

Mk. IV.4
We tried our hand at making an o-ring piston. It work for two shots, then de-laminated the grind wheel. So we went back to the old piston. This time we put one layer of electrical tape to serve as an o-ring. It worked amazingly well. Too well. On the maiden firing, the piston shot back and shattered the fill system. But it got 1800 feet (Google Earth said 1880 approx. using landmarks, so 1800 feet to be conservative) so we were happy. We rebuilt the fill system, went to do a damage shot, and ended up cleaving the entire back half of the valve off. This was at 50 psi. So it's back to the drawing board for Mk. V (always a lucky number for me, so who knows), but as it stands, top range 1800. Our next goal is 1/2 mile. We are going to go for a much lighter piston and smaller piston travel, this should help the issue of self-destruction.

Image
Shattered fill system

Image
Ground eats rocket at 1800 feet.
  • 0

Last edited by deusXmachina on Mon Apr 30, 2007 9:46 am, edited 3 times in total.
User avatar
deusXmachina
Sergeant
Sergeant
 
Posts: 83
Joined: Sun Feb 25, 2007 6:06 pm
Reputation: 0

The Guillotine

Unread postAuthor: deusXmachina » Mon Apr 30, 2007 9:40 am

Even morer pictures:


Image

Image

Image

http://s152.photobucket.com/albums/s161/deusXmachina_spuds/?action=view&current=DSCF1272.flv
Video: You can't see it, but you can probably hear the piston shattering the end of the valve.


Future Plans: 30 and eventually 40 foot barrel, lighter piston, more efficient valve, possibly more chamber volume, large-scale supersonic testing with helium (the hell with supersonic marbles I wanna see a rocket break the sound barrier!).
  • 0

Last edited by deusXmachina on Tue May 01, 2007 11:20 am, edited 3 times in total.
"On a scale from 1-10, I hope you fall in front of a bus."

:white stuff pours out of piston: "What is that? It looks like milk."
"....<i>Well...</i> it's not milk."

YAAAAAAAAYYYY WE'RE DOOMED!
User avatar
deusXmachina
Sergeant
Sergeant
 
Posts: 83
Joined: Sun Feb 25, 2007 6:06 pm
Reputation: 0

Unread postAuthor: Billy Bob » Mon Apr 30, 2007 1:46 pm

:D :D

thats a big one ! :shock:
Very good work. Do you shoot in your garden or put that weapon on your pick up and drive around ?
  • 0

User avatar
Billy Bob
Corporal
Corporal
 
Posts: 72
Joined: Sat Oct 28, 2006 11:53 am
Location: Germany
Reputation: 0

Unread postAuthor: zeigs spud » Mon Apr 30, 2007 2:12 pm

omfg that is huge!!!!!!! musta been a pain puttin all that up lol. well looks nice. mabey a better vid of it tho?
  • 0

User avatar
zeigs spud
Colonel
Colonel
 
Posts: 657
Joined: Tue Apr 04, 2006 10:39 pm
Reputation: 0

Unread postAuthor: super spuder » Mon Apr 30, 2007 3:10 pm

sucks that it blew up :(
  • 0

User avatar
super spuder
Colonel
Colonel
 
Posts: 558
Joined: Fri Apr 06, 2007 9:05 pm
Location: Ontario Canada
Reputation: 0

Unread postAuthor: surfbum » Mon Apr 30, 2007 3:36 pm

THAT THING IS HUGE!

nice job on all the revisions and redesigns
good work, good luck in the contest
  • 0

"i love the graffiti in the physics toilets at uni...
a physics student wrote 'Arts Degree Dispenser' on the toilet paper dispenser"
User avatar
surfbum
Specialist
Specialist
 
Posts: 45
Joined: Tue Apr 03, 2007 12:37 pm
Location: santa barbara, ca
Reputation: 0

Unread postAuthor: Specialist » Mon Apr 30, 2007 3:42 pm

cool. the stand makes it look like a midevil cannon or catapolt. now i know why you built the stand(other than to hold it up) it has a big kick back. nice cannon. i really like that stand.
  • 0

User avatar
Specialist
Major
Major
 
Posts: 375
Joined: Sun Mar 18, 2007 4:22 pm
Location: Illinios
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: lukemc » Mon Apr 30, 2007 3:48 pm

ha i wondered why you would need a sprinkler modded with a sprinkler to shoot but then i saw it and i was like ohhhh well nice build
  • 0

"Those who are different change the world. Those who are the same keep it that way"
User avatar
lukemc
Colonel
Colonel
 
Posts: 565
Joined: Sun Feb 25, 2007 8:48 am
Location: NY
Reputation: 0

Unread postAuthor: iknowmy3tables » Mon Apr 30, 2007 3:57 pm

thats a really awesome big ass gun ... but ...but ... its oh no here comes the D word.. or acronym.... DWV oh no I said it but who cares its big and cool

and cool username :D
  • 0


iknowmy3tables
Major General
Major General
 
Posts: 1558
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Country: United States (us)
Reputation: 0

Unread postAuthor: deusXmachina » Mon Apr 30, 2007 5:05 pm

iknowmy3tables wrote:thats a really awesome big ass gun ... but ...but ... its oh no here comes the D word.. or acronym.... DWV oh no I said it but who cares its big and cool

and cool username :D


Yea....really tell me about it. I'm putting together funds to build the Mk. V - Sch 80 4" Tee, two female cleanouts, a female adapter, and a Sch 80 plug. Then this puppy is really gonna kick.
  • 0

"On a scale from 1-10, I hope you fall in front of a bus."

:white stuff pours out of piston: "What is that? It looks like milk."
"....<i>Well...</i> it's not milk."

YAAAAAAAAYYYY WE'RE DOOMED!
User avatar
deusXmachina
Sergeant
Sergeant
 
Posts: 83
Joined: Sun Feb 25, 2007 6:06 pm
Reputation: 0

Unread postAuthor: Panzerfaust » Mon Apr 30, 2007 5:48 pm

I had always thought that it was odd and kinda silly to use non pressure rated cleanouts in a gun made of pressure rated parts. Hope this warns other people be to be carefull with non pressure rated stuff. You would have to change the design some, and it would add a little dead space behind the piston, but id just say to use a male adapter connected to a reducer connected to your pilot... or a threaded reducer. These are pressure rated and you wont have to worry about them blowing on ya.
now that im dont lecturing.... that is one BEAST of a cannon. Too bad it broke, but id give u a fair chance in the contest. your stand setup is also very nice.
  • 0

User avatar
Panzerfaust
Staff Sergeant
Staff Sergeant
 
Posts: 129
Joined: Tue Apr 17, 2007 4:37 pm
Reputation: 0

Unread postAuthor: iknowmy3tables » Mon Apr 30, 2007 5:52 pm

yeah it sucks how much more it cost just to have the sockets deeper on large fittings, good luck on the next valve
  • 0


iknowmy3tables
Major General
Major General
 
Posts: 1558
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Country: United States (us)
Reputation: 0

Unread postAuthor: Juicey » Mon Apr 30, 2007 7:09 pm

Dude, that's an awsome cannon. I absolutly love the stand. I like the idea of using bungees rather than springs. Great job. Can't wait to see it when u get it up and running again.
  • 0


Juicey
Specialist
Specialist
 
Posts: 46
Joined: Wed Apr 18, 2007 9:04 pm
Reputation: 0

Unread postAuthor: SpudMonster » Mon Apr 30, 2007 7:19 pm

DWV plugs FTW

[/sarcasm]

Seriously though, nice cannon. Quite large to say the least.
  • 0

User avatar
SpudMonster
1st Lieutenant
1st Lieutenant
 
Posts: 250
Joined: Mon Aug 08, 2005 5:54 pm
Reputation: 0

Unread postAuthor: bboymatty » Mon Apr 30, 2007 10:13 pm

haha awesome! I love how your shooting rockets out of it

got any videos to post?
  • 0

User avatar
bboymatty
Staff Sergeant
Staff Sergeant
 
Posts: 109
Joined: Sun Feb 19, 2006 12:12 pm
Reputation: 0

Next

Return to Pneumatic Cannon Database

Who is online

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

Reputation System ©'