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| PCGUY |
 Posted: 02/05/2005 17:28 PM Post subject: True Semi |
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Evil Admin
Joined: 18 Aug 2004
Posts: 1235
4409.82 Spud Bux
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TRUE SEMI
Provided By Mr.Plow - http://www.geocities.com/boomstick989
T he first development of my semi-auto idea was completed weeks ago. It consisted of a tri-chambered design with three independently operated blowgun-modded sprinkler valves linked to a 1" diameter barrel by means of a 1" cross. A tee and small section of pipe just before the barrel acted as the hopper, with a 15 round capacity. Although a complex system of smaller electronically actuated valves connected to a timer relay circuit was devised to make the gun essentially fire full automatic, it never got past the initial phases using 3 plain ol' blowguns. Ammunition was at first a limited number of round wooden balls I found in my basement that loosely fitted the barrel. While the initial design worked, it was extremely unreliable. One test would work perfectly, shooting all 15 balls without jams or other problems, and right after that the next test would go FUBAR in every possible manner! Obviously, it was flawed in several ways. I scrapped the tri-chambered design, for now focusing on resolving the problems encountered with just one chamber. Perhaps sometime soon I'll rebuild the original with all the bugs worked out...
Working out the magazine jamming issues was easy; a little dremeling the inside of the barrel plus plastic balls for ammo that actually fit the barrel did the trick. The most difficult problem was getting the valve to re-seat the diaphragm quickly enough. Since air was continually flowing into the chamber, the valves had the tendency to "honk" after each shot for 4-10 seconds as the diaphragm vibrated quickly. To fix this problem, I removed the inner spring and essentially made a bigger equalization port by adding an air-in line to the top of the valve. Of course, I had to limit the amount of air going to the top of the diaphragm (or else it wouldn't fire), so I added the needle valve with gauge. With the chamber at 40psi and the top restricted to a little less than 10psi, it works like a dream! I can get about 3 shots per 2 seconds, and I estimate the ammo is getting more that 150fps (although I dont have a chrony...so a real number will have to wait)
Provided By Mr.Plow - http://www.geocities.com/boomstick989
| Description: |
| Heres an example of one of the plastic balls that I shoot. |
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16.93 KB |
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3917 Time(s) |
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Here's a side view of the cannon. In case you're wondering, the black tape is cosmetic, hiding the blue cement I used...no, its not taped together!! ;)
Also, as you can see, the air system plugs into a compressor with an industrial plug. The regulator you see is a detroit pneumatics mini-reg I got for free. I love the look of those braided steel lines (also free!) |
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28.59 KB |
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333 Time(s) |
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| Description: |
| Closeup of the valve assembly. If you notice, only two screws are in the top of the valve (I forgot to replace them before taking this pic...I was previously showing off the internals of the valve to a friend) |
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27.75 KB |
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154 Time(s) |
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Last edited by PCGUY on 05/02/2006 10:02 AM; edited 1 time in total |
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| theexp |
| Posted: 02/06/2005 15:43 PM Post subject: |
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Master Sergeant
Joined: 03 Oct 2004
Posts: 157
66.62 Spud Bux
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nice, i hope you get the jamming done, but i like it.
Real cool.
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| fred_roux |
| Posted: 03/28/2005 20:55 PM Post subject: |
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Specialist
Joined: 14 Feb 2005
Posts: 46
44.18 Spud Bux
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coooool...a simple way to get a semi-auto canon...thats really cool!!!!!....u shoult change the barrel for a golf ball barrell 
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| julz |
| Posted: 05/06/2005 0:35 AM Post subject: |
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Sergeant Major
Joined: 17 Apr 2005
Posts: 178
176.91 Spud Bux
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Darn... I just had his idea the other day and thought I was the first one  . Good work though. I reckon i will make soon a 3-5 chambered, single barreled cannon. The only thing i can find that wold be dodgey would be the size of the chamberes, as the gun needs to be portable. I hope to have this built within the next...  year.  It will take a while and must be a secret bye!
---Julz
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| spudshot |
| Posted: 05/06/2005 2:26 AM Post subject: |
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Brigadier General
Joined: 03 Oct 2004
Posts: 1044
41304.56 Spud Bux
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| as far as arranging the chambers to be portable julz, you could just use elbows to make the chambers go the same way as the barrel, so all you have is a cannon slightly longer than the barrel
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| deathtodeer666 |
| Posted: 09/06/2005 0:29 AM Post subject: |
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Staff Sergeant
Joined: 02 Sep 2005
Posts: 126
273.02 Spud Bux
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| aaah! how do you make the sprinkler valve work with the blowgun, I can under stand if it just releasis presure.
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| spudshot |
| Posted: 09/06/2005 4:30 AM Post subject: |
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Brigadier General
Joined: 03 Oct 2004
Posts: 1044
41304.56 Spud Bux
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| there is pressurized air on both sides of the diaphragm, using the blowgun you exhaust the air on top of the phragm, so there is no pressure above, and your chamber volume is still pushing from below, that pushes the phragm up and allows the air go to to the barrel
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| saladtossser |
| Posted: 09/06/2005 13:19 PM Post subject: |
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SpudZilla
Joined: 26 Mar 2005
Posts: 1237
98.19 Spud Bux
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| i honestly dont know how this gun loads. and i dont get y there are 2 hoses coming from the valve, those clear hoses dont take a lot of pressure.
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| sgort87 |
| Posted: 09/18/2005 9:58 AM Post subject: |
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The Gort
Joined: 18 Sep 2005
Posts: 869
924.49 Spud Bux
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| Neat! But you need to elaborate on your system there. The valves and loading.
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| Andrew52 |
| Posted: 03/28/2006 22:21 PM Post subject: |
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Sergeant Major
Joined: 26 Feb 2006
Posts: 196
41.40 Spud Bux
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| yes but its still an awesome gun
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| spud yeti |
| Posted: 05/15/2007 3:39 AM Post subject: |
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can i change this name
Joined: 08 May 2007
Posts: 1043
14.05 Spud Bux
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| How does it load for semi auto??
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| chaos |
| Posted: 05/15/2007 3:51 AM Post subject: |
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Brigadier General
Joined: 17 Jan 2007
Posts: 1222
913.08 Spud Bux
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Oh No's
check the dates before posting pwease.
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| cb4289 |
| Posted: 05/16/2007 0:48 AM Post subject: |
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Sergeant First Class
Joined: 04 May 2007
Posts: 133
233.09 Spud Bux
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| spudshot wrote: | | there is pressurized air on both sides of the diaphragm, using the blowgun you exhaust the air on top of the phragm, so there is no pressure above, and your chamber volume is still pushing from below, that pushes the phragm up and allows the air go to to the barrel |
so on those air nozzle triggers that bcarms.com sell's when you pull the trigger dose air come out the bottem or not 
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| A-98 |
| Posted: 05/16/2007 1:27 AM Post subject: |
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Pussy Lover
Joined: 27 Apr 2006
Posts: 907
135.08 Spud Bux
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*sigh*
look, heres a link to all of your needs. CLICKY! and if not that then this
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| cb4289 |
| Posted: 05/16/2007 1:33 AM Post subject: |
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Sergeant First Class
Joined: 04 May 2007
Posts: 133
233.09 Spud Bux
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| oh now i know what a modded sprinkler valve is and how it works... cool
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