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True Semi

Unread postPosted: Sat Feb 05, 2005 6:28 pm
Author: PCGUY
<div align="center">TRUE SEMI

Provided By Mr.Plow - <a href="http://www.geocities.com/boomstick989">http://www.geocities.com/boomstick989</a>

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 - <a href="http://www.geocities.com/boomstick989">http://www.geocities.com/boomstick989</a></div>

Unread postPosted: Sun Feb 06, 2005 4:43 pm
Author: theexp
nice, i hope you get the jamming done, but i like it.
Real cool.

Unread postPosted: Mon Mar 28, 2005 9:55 pm
Author: fred_roux
coooool...a simple way to get a semi-auto canon...thats really cool!!!!!....u shoult change the barrel for a golf ball barrell :twisted:

Unread postPosted: Fri May 06, 2005 1:35 am
Author: julz
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... :roll: year. :) It will take a while and must be a secret bye!
---Julz

Unread postPosted: Fri May 06, 2005 3:26 am
Author: spudshot
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

Unread postPosted: Tue Sep 06, 2005 1:29 am
Author: deathtodeer666
aaah! how do you make the sprinkler valve work with the blowgun, I can under stand if it just releasis presure.

Unread postPosted: Tue Sep 06, 2005 5:30 am
Author: spudshot
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

Unread postPosted: Tue Sep 06, 2005 2:19 pm
Author: saladtossser
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.

Unread postPosted: Sun Sep 18, 2005 10:58 am
Author: sgort87
Neat! But you need to elaborate on your system there. The valves and loading.

Unread postPosted: Tue Mar 28, 2006 11:21 pm
Author: Andrew52
yes but its still an awesome gun

Unread postPosted: Tue May 15, 2007 4:39 am
Author: spud yeti
How does it load for semi auto??

Unread postPosted: Tue May 15, 2007 4:51 am
Author: chaos
Oh No's



check the dates before posting pwease.

Unread postPosted: Wed May 16, 2007 1:48 am
Author: cb4289
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 :?:

Unread postPosted: Wed May 16, 2007 2:27 am
Author: A-98
*sigh*

look, heres a link to all of your needs. CLICKY! and if not that then this

Unread postPosted: Wed May 16, 2007 2:33 am
Author: cb4289
oh now i know what a modded sprinkler valve is and how it works... cool