Find fields & stores near you!
Find fields and stores
Zipcode
PbNation News
PbNation News
Community Focus
Community Focus

Reply
 
Thread Tools
Old 04-11-2010, 09:32 AM #1
Boom Master
Scenario Player
 
Join Date: May 2009
Location: St. Louis MO, USA, EARTH
Quick and Dirty Breechloader

Caution! Now this is BEING Built. It has not been FIRED yet. So proceed at your own RISK.


Update: It has been built. Link at http://www.pbnation.com/showthread.p...0#post69862960


I will add a test report when completed but I am confident it will get the job done.

All of us Cannoneers tend to overbuild our breechloaders. My self included. Must be a Guy Thing or fear of needing plastic surgery.

Actually, there is suprisingly little pressure build up in the barrel during firing. The Nerf is So Light, pressure doesn't build. My Shorty which operates at the HIGH END of most cannon operating pressure at 145 psi generates a max pressure of 40 psi for the first milisecond and the graph drops exponentially to ZERO over the next four miliseconds when the Nerf exits the barrel. That is from Dave Halls Gas Gun Design Tool. In the field, I discovered you can hold your bare palm over the breech of a cannon and FIRE a Nerf that goes screaming out the barrel. Just a Big Noisy Puff, not a BLAST of air.

Here is a couple of pictures of my first overbuilt Breechloader.





Clamps on top and bottom and wedges tight on those tapered angled aluminum.

I am building a Hand Held Breech Loader using this PVC DRAIN from LOWES.

Bought the one that had the beefest screw holes to secure the breech plate and would accept 2 or 3 inch PVC pipe.



First wrinkle is the Nerf would be a bit too far back relative to the air Inlet hole.



So you could cut off some of the T fitting and/or the Drain. I opted for the drain because it was rather thick walled. Remember you can fudge like this because there is NOT a lot of pressure build up during firing. Unless you forget to take out your barrel plug and didn't vent it just in case you DID forget.

This solved the Nerf loading problem.



For the breech plate, I'm going with 1/4" plywood.

Here is a pic of a mock up.





You will note the drain had a ridge that has to be reamed out to accept a nerf easily. You can see the slot offers a source for air to leak out. Again, as long as it leaks the same amount, it doesn't matter. However, Since that ridge is going to be removed anyway, I plan to extend the 2" pvc pipe rearwards about 1/8"so that the end of that 2" pipe is FLUSH with the breech plate to minimize the leak potential. ANOTHER really Good reason to extend that 2 inch pipe is the FORCE exerted on the breech plate. 40 psi x the area of that 4" drain is 502 pounds of force. That got MY attention even IF it is for only 1 milisecond. However that same 40 psi on a 2" pipe flush agaisnt that plate is 125 pounds of force. 75% less force on that breech plate and I wouldn't MIND if any leakage out of the 2 inch pipe is vented out that slot instead of building up. It is a good idea to pay attention in physics class...





Builders also worry about sealing the breech. Making it air tight. It is NOT critical and can leak a bit. What is critical is that it leaks the SAME amount of air on each shot so accuracy/range is not affected.

In the FIRST breechloader I used a coarse thread Machine Screw for the pivot. (4-20) and there was NO pivot. The bolt was fixed and attached to the breech plate that moved and was threaded into a nut fixed to the cannon plate. So when I opened the breech a quarter turn, the breech plate literally unscrewed a quarter turn and OPENED a small gap between the cannon and breech plate. Enough to allow it to open easily and tighten up when closed.

Now this is BEING Built. It has not been FIRED yet. I will add a test report when completed but I am confident it will get the job done. Something to ponder for now...
__________________
Carefully planned irresponsibility is the KEY to mental health.

If you haven't grown up by age 50........

You don't have to......

Last edited by Boom Master : 01-17-2011 at 11:26 AM.
Boom Master is offline   Reply With Quote
Old Sponsored Links Remove Advertisement
Advertisement
Old 04-11-2010, 11:10 AM #2
AmazingBilldo
I..... win?
 
AmazingBilldo's Avatar
 
Join Date: Aug 2006
Location: *989*
use a smaller OD pipe and end cap mounted inside a toilet flange as a twist lock breach plug. that will push the nerf farther into the breach, and potentially mate to the drain fitting.
__________________
Personal Responsibility is never obsolete.

"...I had to be at that there crossroads last midnight, to sell my soul to the devil."
"Well ain't it a small world, spiritually speaking? Pete and Delmar just been baptized and saved. I guess I am the only one here that remains unaffiliated."

Cocker parts for sale:
http://www.pbnation.com/showthread.php?t=3735953

Last edited by AmazingBilldo : 04-11-2010 at 11:21 AM.
AmazingBilldo is offline   Reply With Quote
Old 04-11-2010, 12:02 PM #3
Boom Master
Scenario Player
 
Join Date: May 2009
Location: St. Louis MO, USA, EARTH
Yep I gave those a serious look too. Fine for a tank cannon. I went with this smaller and lighter set up for the hand held.
__________________
Carefully planned irresponsibility is the KEY to mental health.

If you haven't grown up by age 50........

You don't have to......
Boom Master is offline   Reply With Quote
Old 04-27-2010, 07:24 PM #4
cman7896
 
 
Join Date: Apr 2010
We used one back in the day for a howleiser. Played with the doom troopers had rounds all ready to do with a spyder celinoid.
cman7896 is offline   Reply With Quote
Old 05-24-2010, 04:25 PM #5
Boom Master
Scenario Player
 
Join Date: May 2009
Location: St. Louis MO, USA, EARTH
Another possible resource: Saw them at my local Woodworking supply place for $5 for the plastic ones that I believe would be substantial enough for our application.

Search: Dust Collection "Blast Gates"

Available in plastic, galvanized and stainless steel. Also pneumatically activiated. Give you aspiring autoloading cannoneers any ideas?

Look like this:



$2.99 with $7 shipping so BUY several with your buddies..

One link of many at:

http://www.tools-plus.com/woodstock-w1006.html

Haven't checked the PVC fitting and pipe compatiability yet. Will add here. Note many do NOT open all the way but could be easily modified or if you use a 2 1/2" would still pass a Nerf to load with no problem..
__________________
Carefully planned irresponsibility is the KEY to mental health.

If you haven't grown up by age 50........

You don't have to......

Last edited by Boom Master : 05-26-2010 at 02:28 PM.
Boom Master is offline   Reply With Quote
Old 05-25-2010, 10:50 AM #6
CNCRouterman
 
 
Join Date: Nov 2009
I've been around cabinet shop dust collectors and accessories for a couple of decades, and my experience is that those blast gates are built with very sloppy tolerances to allow them to function even when caked with sawdust and pitch. Pretty sloppy fit, and they move a lot of air even when closed.

I would not recommend them for this application. I try to avoid their use even for what they were designed for, which is to compensate for having too many Dust Collection ports for the size pipe and or size dust collector in use. There is justification for their use on equipment that you wish to reduce the air flow during maintenance, such as on a wide belt sander when it is time to change belts, or a moulder when you don't want a dropped tool to get sucked three or four feet along the pipe run which then means you end up shutting down the Dust Collector to retrieve the tool (usually by taking a lot of stuff apart, the more expensive or rare the tool, the more stuff you have to take apart to reach it, guess how I know about that) which can really annoy the other folks trying to run the panel raising shapers, or the gang ripsaw operator, or pretty much every body else in the shop working at a machine.
CNCRouterman is offline   Reply With Quote
Old 05-25-2010, 11:32 AM #7
Boom Master
Scenario Player
 
Join Date: May 2009
Location: St. Louis MO, USA, EARTH
Yes, they do leak a lot of air but they do make air tight ones made out of galvanized and even stainless. Cost quite a bit more...

Still, you CAN leak a lot of air and still function properly in a cannon. You CAN hold your palm over the open breech and it will still shoot the Nerf 230 fps. There is surprisingly little pressure build up in the breech because those nerfs are so light and bore fit so loose.

Just a thought.
__________________
Carefully planned irresponsibility is the KEY to mental health.

If you haven't grown up by age 50........

You don't have to......

Last edited by Boom Master : 05-25-2010 at 11:37 AM.
Boom Master is offline   Reply With Quote
Old 05-25-2010, 10:21 PM #8
splntercell
TopGun Knight
 
Join Date: Apr 2008
I used an 2 inch expandable coupler found in the electrical department to make a breech loader and it works surprisingly well. All i did was cut a hole big enough to fit the nerf through on the male part. It comes with 2 orings at the end I made a groove on the other side of the hole and relocated one of the orings to the that groove. I get 0 air loss all you have to do is slide the barrel forward drop the nerf in and slide it back.
__________________
Topgun knights
Proudly sponsored by:
TopGun paintball games, Empire
splntercell is offline   Reply With Quote
Old 01-17-2011, 11:20 AM #9
Boom Master
Scenario Player
 
Join Date: May 2009
Location: St. Louis MO, USA, EARTH
Built and field tested it. Link and discussion AT:

http://www.pbnation.com/showthread.p...0#post69862960
__________________
Carefully planned irresponsibility is the KEY to mental health.

If you haven't grown up by age 50........

You don't have to......
Boom Master is offline   Reply With Quote
Old 05-12-2011, 08:52 PM #10
Boom Master
Scenario Player
 
Join Date: May 2009
Location: St. Louis MO, USA, EARTH
Geez, forgot to post the pics of the final product. It worked fine as expected.


Breech OPEN:



Breech CLOSED:


I would build the plywood cover out of 1/2" - 3/8" as the point between the handle and the slot is a weak point. Broke one off BEFORE the game, thankfully.



Here is the handy dandy SWIVEL for the air hose discharging into the breech from the main valve. on the back of the tank.



We used 3/4" plastic flex electrical conduit from LOWES. 1/2" flex conduit was too small and a flow restriction. Didn't trust the push in fitting so we hose clamped it. No problems and worked well.
__________________
Carefully planned irresponsibility is the KEY to mental health.

If you haven't grown up by age 50........

You don't have to......
Boom Master is offline   Reply With Quote
Old 02-08-2012, 09:38 AM #11
Boom Master
Scenario Player
 
Join Date: May 2009
Location: St. Louis MO, USA, EARTH
Built another version of the one above using a shower drain. Definately not in the typical configuration. The velocity was difficult to get a nerf up to speed with a 28" barrel as with the first version.

I'm coming to the conclusion that quite a bit of air is leaking out the breech door and compromising the performance a fair amount. If you want to do this route, you might want a bit larger volume air chamber from the 100 ci that I used and live with a longer barrel.

Ponder some ways to limit the air loss out the breech door. Mine was 1/4" thick on both. May be Flexing and bowing outward. Maybe 3/8" - 1/2" would be stiffer and maybe help.

FYI Bought a sewer drain slide gait for $22. RV Parts Supply. Will go right over a 2" pipe. Cut off a bit of the length off a T fitting and it should be short enough to fit a Nerf bulb forward of the air inlet. We will see how that works. Should seal well being water tight. The problem with every one I saw was the OD of the gate is a tad smaller diameter than a Nerf. But just barely. Will see how well it feeds Nerfs and get out the drum sander and make it a little bigger if needed. If that doesn't work, they make 3".
__________________
Carefully planned irresponsibility is the KEY to mental health.

If you haven't grown up by age 50........

You don't have to......

Last edited by Boom Master : 02-08-2012 at 09:56 AM.
Boom Master is offline   Reply With Quote
Old 02-08-2012, 05:22 PM #12
BLC_BOOM
 
 
Join Date: Aug 2008
I have been using the rv sewer drain gate valve for a few years in our tank. It seems to work fine. The only problem that I have had with it is that the plastic flange that comes with it is thin and brittle. I have managed to break the cormners off ofof 2 flanges while bouncing around in the turret.
__________________
Matt Bolinger
BlackLight Company Paintball Team

Quick Strike PAV
BLC_BOOM is offline   Reply With Quote
Old 02-08-2012, 08:03 PM #13
Haz-Mat
Team BlackList
 
Haz-Mat's Avatar
 
Join Date: Feb 2011
Location: San Antonio, TX
I've been looking for a Carrier/Door Kit for a 2" like the one below. They seem to be made for 4" and larger only. Will most likely make one.

__________________
HazMat
Team Black List
Haz-Mat is offline   Reply With Quote
Reply


Thread Tools

Posting Rules
Forum Jump