Author Topic: Where to find write up on O2 Tank Cannon (Read 3295 times)

Cannon salute · « **on:** February 11, 2012, 01:07:00 PM »

I am building an O2 Cannon and would like to do it right, not half assed and dangerous. Any plans for this? Chamber design, OAL, type of tank needed, method of chamber fitting (ie where to weld, reccomended steel for chamber), chamber dimensions and everything else. Thanks in advance.

Also I have seen the use of percussion caps instead of fuses, is there a kit for this?

Double D · « **Reply #1 on:** February 11, 2012, 04:45:25 PM »

Well here is one post opened just last week. Check the reference sticky and you may find links to a couple of others.

Cannon salute · « **Reply #2 on:** February 11, 2012, 06:04:24 PM »

Quote from: Double D on February 11, 2012, 04:45:25 PM

Well here is one post opened just last week. Check the reference sticky and you may find links to a couple of others.

Where is one??

BoomLover · « **Reply #3 on:** February 11, 2012, 08:06:32 PM »

Hey, Double D, I'm with Cannon Salute...didn't see a link....can you hit it again? thanks.........

Double D · « **Reply #4 on:** February 12, 2012, 04:06:51 AM »

http://www.gboreloaded.com/forums/index.php/topic,251175.0.html

http://www.gboreloaded.com/forums/index.php/topic,250125.0.html

From Reference sticky.

http://www.gboreloaded.com/forums/index.php/topic,36962.0.html

When I search bowling ball mortar in the cannon forum, I got 6 pages of hits. Not all are build topics.

Cannon salute · « **Reply #5 on:** February 12, 2012, 04:55:36 AM »

Seems like most of them cut the top of the cylinder and insert a plug, which is sort of contradictory to what I have been told. It seems by cutting and welding you are compromising the integrity of the pressure vessel, but I am aware of the powder chamber rule of 1 to 3 so it seems doing it without a plug is sketchy at best. I also see that some people have the top of the tank intact, is it advisable to cut the entire domed portion of that tank off or just the neck?

I also keep hearing about vent tubes, can someone elaborate on vent tubes?

Artilleryman · « **Reply #6 on:** February 12, 2012, 06:38:08 AM »

Vent tubes (bushings) are used today when a barrel has a liner. This is to provide a continuous passageway. A gap can open up between the liner and the barrel due to corrosion. This gap could hold an ember that could set off a powder charge at the wrong time. Historically this vent piece could be removed when it became worn and replaced. It could also be removed to help remove a projectile that had been deliberately jammed in the breech to keep the gun from being fired (a form of spiking).

Cannon salute · « **Reply #7 on:** February 12, 2012, 06:56:34 AM »

Ok so its only needed if you have a liner, which I wont, using a O2 tank.

Double D · « **Reply #8 on:** February 12, 2012, 08:45:54 AM »

Quote from: Cannon salute on February 12, 2012, 04:55:36 AM

Seems like most of them cut the top of the cylinder and insert a plug, which is sort of contradictory to what I have been told. It seems by cutting and welding you are compromising the integrity of the pressure vessel, but I am aware of the powder chamber rule of 1 to 3 so it seems doing it without a plug is sketchy at best. I also see that some people have the top of the tank intact, is it advisable to cut the entire domed portion of that tank off or just the neck?

I also keep hearing about vent tubes, can someone elaborate on vent tubes?

I think perhaps you misunderstand what is going on here. The powder chamber is the mortar. The pressure vessel-tank is nothing more than a decorative expansion chamber and ball holder. A pressure vessel-tank is used for convenience-right I.D. and nothing more.

Here is a drawing from one of the links I provided.

The vent provides a path from chamber to outside of tank.

Cannon salute · « **Reply #9 on:** February 12, 2012, 02:07:31 PM »

Drawings, very basic drawings, only go so far. Anyone have actual pictures? If the pressure vessel tank is only a ball holder, then you are essentially taking a small mortar 1-2" bore and welding it inside the tank? The only difference being that instead of having a powder chamber in the mortar, the whole mortar follows the 1:3 rule since it is the powder chamber for the tank? Or did that make any sense?

Double D · « **Reply #10 on:** February 12, 2012, 02:10:38 PM »

Take a look at the links in the post up thread..

Cat Whisperer · « **Reply #11 on:** February 12, 2012, 03:25:05 PM »

Quote from: Cannon salute on February 12, 2012, 02:07:31 PM

Drawings, very basic drawings, only go so far. Anyone have actual pictures? If the pressure vessel tank is only a ball holder, then you are essentially taking a small mortar 1-2" bore and welding it inside the tank? The only difference being that instead of having a powder chamber in the mortar, the whole mortar follows the 1:3 rule since it is the powder chamber for the tank? Or did that make any sense?

I think you're close, it not right on. The powder chamber (1:3) is welded inside the tank. Are we not saying the same thing? The tank then becomes the ball-holder and guide for it's initial 16" of travel.

Double D · « **Reply #12 on:** February 12, 2012, 03:27:59 PM »

Quote from: Cannon salute on February 12, 2012, 02:07:31 PM

Drawings, very basic drawings, only go so far. Anyone have actual pictures?

Is that a polite way of saying the drawing sucks--agree.

Is this one better?

I think it is.

BoomLover · « **Reply #13 on:** February 12, 2012, 03:53:07 PM »

Double D, that is Much better! Thanks! (Almost like a photo!) Boomlover

Cannon salute · « **Reply #14 on:** February 12, 2012, 04:36:37 PM »

Another question then. Assuming we are using intelligent loading procedures, wrapping our charges in foil etc, what procedure would be used to place the charge in the chamber? You definitely wont be throwing it in there because it would likely miss the chamber completely, so would you then put your arm in the tank with a handful of charge to place it in the chamber? I sure wouldnt.

Is the ignition source via the vent tube?

Oh and the new drawing is great.

Double D · « **Reply #15 on:** February 12, 2012, 06:14:30 PM »

Quote from: Cannon salute on February 12, 2012, 04:36:37 PM

Another question then. Assuming we are using intelligent loading procedures, wrapping our charges in foil etc, what procedure would be used to place the charge in the chamber? You definitely wont be throwing it in there because it would likely miss the chamber completely, so would you then put your arm in the tank with a handful of charge to place it in the chamber? I sure wouldnt.

Is the ignition source via the vent tube?

Oh and the new drawing is great.

No cartridges in the mortar, load the powder loose.
Use a funnel.... http://www.gboreloaded.com/forums/index.php/topic,165690.0.html

You really do need to tale a look at the reference sticky. It is full of neat ideas that folks have come up with over the years. http://www.gboreloaded.com/forums/index.php/topic,41634.0.html

Cannon salute · « **Reply #16 on:** February 13, 2012, 02:36:12 PM »

I looked at the sticky And read quite a few of the links. So far I have made a short materials list: O2 tank, 1018 round stock 6" long ;4 or 5" diameter with 1.?? Bore; 4" deep chamber, 1018 2" round stock 8" long for trunnion

Cannon salute · « **Reply #17 on:** February 13, 2012, 03:36:31 PM »

Here is a rough design

Chamber is 4 in deep, 2 in breech wall. Let me know if you think the design is sound.

Still cant find any pictures of vent tube designs, searched the forums and google.

jamesfrom180 · « **Reply #18 on:** February 13, 2012, 04:21:38 PM »

Just a thought, is it for asthetic reasons you would use the vent tube method? Why not weld the tank to the muzzle of the chamber?

GGaskill · « **Reply #19 on:** February 13, 2012, 05:09:18 PM »

Lessens the stress on the weld since the tube is bearing directly on the trunnion.

Cannon salute · « **Reply #20 on:** February 13, 2012, 05:24:01 PM »

Quote from: jamesfrom180 on February 13, 2012, 04:21:38 PM

Just a thought, is it for asthetic reasons you would use the vent tube method? Why not weld the tank to the muzzle of the chamber?

To be honest with you, I am not 100% on the vent tube myself(atleast the design aspect of it), but I concur with GGaskill regarding stressing the weld. By welding the tank to the trunnion itself you reduce stress by a good bit, think of welding a block on the end of a pole vs drilling a hole in the block and sliding it over the pole then welding it. Leverage. Not to mention you will have more weld surface area by welding to the trunnion.

Double D · « **Reply #21 on:** February 13, 2012, 05:26:46 PM »

Quote from: jamesfrom180 on February 13, 2012, 04:21:38 PM

Just a thought, is it for asthetic reasons you would use the vent tube method? Why not weld the tank to the muzzle of the chamber?

Well for one thing how many real mortars have you seen that have a dinky powder chambers sticking out the back. Doing it that way is amateurish and says the builder really doesn't know what they are doing.

But no isn't just aesthetics . Welding to the muzzle, puts a weld right at the muzzle to catch the blast and powder fouling which can attack the weld. The weld at the back still can be contaminated but if it won't be as severe as if it is in front.

Cannon salute · « **Reply #22 on:** February 13, 2012, 05:45:42 PM »

So for my vent tube design, I am thinking or using either a threaded rod with a hole through it or tubing with threads on either end. Then drill and tap the chamber, hopefully this vent tube doesnt become a missile. Generally how large should the tube be? Just large enough for a fuse?

BoomLover · « **Reply #23 on:** February 13, 2012, 05:48:08 PM »

George and Double D...correct me, please, if I'm wrong, but it seems after careful reading, that the term itself, and the purpose of creating a"Vent Tube" is causing some confusion. Also, the "Tank" actually setting on the "Trunnion", along with method of attachment, is still a foreign concept. Weld this here, screw that there, grind a flat, or leave it round, strength at this point, weakness at that point.....Double D, your last drawing was the clearest yet of the construction method, and the only thing that would have made it any clearer would have been to actually add all the dimensions/numbers. It was just like a "cut away" photo! Can either of you explain the method of construction of the "Vent Tube", and it's purpose for being built that way? Unless I'm miss reading, this is a sticking point. I'm not a machinist, but I built mine that way when I made the soda can Mortar, having the actual drilling done "off campus", so to speak. You spelled it out rather well in describing your K.I.S.S. Mortar. Thanks, BoomLover (Just read the latest entries, it is getting clearer!)

Double D · « **Reply #24 on:** February 13, 2012, 05:54:54 PM »

The vent goes into the back of the power chamber and not the front. The vent provides an unbroken path from out outside to the powder chamber.

I have posted my version of a vent tube a number of times. I make mine from socket screws or bolts.

I put the screw in the lathe in a screw mandrel I made to hold the screw Drill a pilot hole with a center drill to get through surface hardening.

Then drill the rest of the way through.

Here the vent liner is in place in my popcan mortar.

Here you can see the hole through the screw.

The big screw, that will be the vent liner for my bowling ball mortar.

Double D · « **Reply #25 on:** February 13, 2012, 06:00:01 PM »

Quote from: Cannon salute on February 13, 2012, 05:45:42 PM

So for my vent tube design, I am thinking or using either a threaded rod with a hole through it or tubing with threads on either end. Then drill and tap the chamber, hopefully this vent tube doesnt become a missile. Generally how large should the tube be? Just large enough for a fuse?

You got it! Thread in is how it was done on original cannons-they were copper.

Cannon salute · « **Reply #26 on:** February 13, 2012, 06:11:11 PM »

Douglas- does pressure on the vent screw ever cause issues, such as ejection? In simplified terms it seems that the vent is basically a straight ignition path to the chamber, as opposed to traditional cast cannons which have "vent" holes, but note vent tubes. If one was using a solid round stock the tube wouldnt be necessary. only when welding the combustion chamber into a larger sleeve or tube where there is a gap, even a minute gap(as appears to be the case with your soda can mortar), is the tube necessary to help prevent corrosion in between the chamber and sleeve. It seems it wouldnt be all that necessary on a mortar with a 4" chamber with a 8" tank, because some powder will get around the chamber irregardless, but it would make sure you get the fuse into the chamber so you wouldnt have to fish around.

Double D · « **Reply #27 on:** February 13, 2012, 06:25:28 PM »

Several post made all at once---Jim did I get your question answered.

Actually the drawing I made doesn't need dimensions it uses rules of thumb. It is the standard wall thickness must be the same as or thicker than diameter of the chamber. what ever size it is.

One thing I haven't mentioned is how to determine depth of chamber and length of chamber for a while. I find no need under normal circumstance to exceed the maximum recommend loads of the N-SSA and AAA. I determine what diameter powder chamber I am going to use and compute the maximum charge for the diameter. Then I drill or bore a hole in a piece of wood until it will deep enough to hold the maximum powder charge. I measure the depth of the hole. That is my powder chamber depth. I as tot he depth the one powder chamber diameter and that s my length of the entire chamber piece.

BoomLover · « **Reply #28 on:** February 13, 2012, 06:33:34 PM »

Yep! A picture is worth a thousand words, and your pictures did the trick. Exactly how I did mine, except I don't have a lathe, so a friend did the actual drilling of the bolt. I think you cleared it up for those who were still having questions. Thank you!

Double D · « **Reply #29 on:** February 13, 2012, 07:22:48 PM »

Quote from: Cannon salute on February 13, 2012, 06:11:11 PM

Douglas- does pressure on the vent screw ever cause issues, such as ejection? In simplified terms it seems that the vent is basically a straight ignition path to the chamber, as opposed to traditional cast cannons which have "vent" holes, but note vent tubes. If one was using a solid round stock the tube wouldnt be necessary. only when welding the combustion chamber into a larger sleeve or tube where there is a gap, even a minute gap(as appears to be the case with your soda can mortar), is the tube necessary to help prevent corrosion in between the chamber and sleeve. It seems it wouldnt be all that necessary on a mortar with a 4" chamber with a 8" tank, because some powder will get around the chamber irregardless, but it would make sure you get the fuse into the chamber so you wouldnt have to fish around.

Traditional original cast cannon also had vent liners, Here is one in an original Mountain Howitzer.

They served to provide as a means to repair the vent when it eroded.

As you say it is absolutely necessary in this pressure vessel mortar as so you can get the fuse to the charge. Surprisingly on this design very little powder fouling goes rearward. Rear of the muzzle inside the tank stays fairly clean. That is another reason to weld the tank to the bottom and not the mouth. Now if you didn't have a vent liner the gases coming out the side of the chamber would blast all over inside and might even put a strain on the chamber and break it loose. It also might even blow the vent hole in the tank out.