Author Topic: differant way to construct a cannon barrel (Read 2029 times)

sterling · « **on:** September 16, 2012, 05:15:42 AM »

hey guys.

got a friend that is helping me make a barrel.Hes a tool and die maker and has access to the lathe to mill the barrel but the problem is that his lathe can only fit a 3 foot pice. our barrel is going tobe 8 feet long. its main use is for ceremonial and to fire off a 12 g shell that is a blank only.no projectile will be used at any time.

So we r thinking of taking a 3 foot 8"diam pice of hollow pip and then welding a 6 foot 7" diam inside to give us a total lenth of 6 feet.so right now we have sorta a sleve over the rear were the breach is. no we weld in a 8 foot 6" diam inside to give us the final 2 feet at the end. now we have three peices of hollow pipe inside each other to give that step down look from breach to end of barrel.

so now we will wet fit and weld the breach part to the rear of the barrel.

i know there is more to add here but my question is that this will be only used for shooting blanks in a controld envierment. what should the min spec that the tub steel should be and what gauge?

Cat Whisperer · « **Reply #1 on:** September 16, 2012, 07:23:37 AM »

A GOOD steel to use is regular good old 1018 cold rolled steel. It is weldable, it machines easily AND it takes the repeated pressure.

Make the walls around the shell to be at least equal in thickness to the bore diameter.

MOST of the pressure is encountered early-on (in the area around the shell).

sterling · « **Reply #2 on:** September 16, 2012, 07:39:34 AM »

thanks for the reply.

We r going to use rolled steel as you sugested and was thinking of going 1/2" thick since i have been reading cannon sleves should be around 3\8 " thick so if i were to go 1\2" i should be ok?

thanks

GGaskill · « **Reply #3 on:** September 16, 2012, 09:12:06 AM »

I would prefer a 3/4" wall over the chamber and in front for a couple of inches. And DO NOT USE any kind of pipe for making cannons. It is not strong enough. Get some seamless tubing; it is available in smaller sizes, too.

sterling · « **Reply #4 on:** September 16, 2012, 10:16:08 AM »

thanks GGaskill. but remeber I will have three peices 1\2" thick at the breach so total would be 1.5 ".

the whole idea is to get away with not milling a solid piece of steel. but in the same aspect being safe and having the proper thickness..

the idea is kinda like a telascope that is calaps.the tubes are inside each other.

oldsoldja · « **Reply #5 on:** September 16, 2012, 10:42:37 AM »

as kids we shot 12 gauge shells off in 3/4 black pipe, over and over again with never a failure, just dont cap both ends and it wont blow up.

sterling · « **Reply #6 on:** September 16, 2012, 10:48:23 AM »

agreed.wont be caping both ends.one end will be the breach the other end will be the rest of the barrel. just the breach end will have two sizes of tubing around it to get the look of a cannon barrel

Double D · « **Reply #7 on:** September 16, 2012, 01:01:48 PM »

Quote from: oldsoldja on September 16, 2012, 10:42:37 AM

as kids we shot 12 gauge shells off in 3/4 black pipe, over and over again with never a failure, just dont cap both ends and it wont blow up.

Yeah when we were kids and didn't know better we did a lot of stupid things and got away with it. Now we are older and understand how dangerous stuff like that is. Sorry but black pipe will blow up!!!

Do not use any pipe ever to build a cannon it is an accident waiting for a place to happen. We have any number of cannon accidents recorded here that the witnesses start of saying "we have been shooting it for years with out a problem".

Sterling in an earlier PM in response to you query, I pointed you to the cannon construction sticky and the guidelines of the N-SSA for building you cannon. I suggest you pay close attention to those suggestion. You are building a salute gun for a bunch cadets. If you cut corners and skip safety and one of these cadets get injured you are on record here of being warned.

You are going have to machine this tube. Since it is going to be a 12 guage balnk gun , you need some means of opening and closing the breech and locking it shut. You will need to machine a 12 gauge chamber. How are you going to do the these things?

You can slide one tube inside another and build the tube up to get safe dimensions.

GGaskill · « **Reply #8 on:** September 16, 2012, 08:31:06 PM »

There is nothing wrong with telescoping tubes as long as they are tightly fitted to each other. But they need to be made from good material and standard galvanized or black iron water/gas pipe is not very strong stuff. Search the internet looking for some strength figures and you will find its strength is less than 2000 psi in the small sizes and less than 1000 psi in larger sizes.

Let's look at your proposal more closely.

So we are thinking of taking a 3 foot 8" diam piece of hollow pipe and then welding a 6 foot 7" diam inside to give us a total length of 6 feet. So right now we have sorta a sleeve over the rear where the breach is. Now we weld in a 8 foot 6" diam inside to give us the final 2 feet at the end. Now we have three pieces of hollow pipe inside each other to give that step down look from breach to end of barrel.

So it looks like you are going to have a final bore diameter of 5 1/2" or so. You will need some kind of a breech plug to chamber the 12 gauge shell for, and some kind of mechanism to close the breech and fire the shell. It is my guess that a 12 gauge blank fired in an 8 foot long by 5.5" diameter bore will make virtually no external sound since there is so much volume in the bore it will act like a muffler. Even if you were to use a 3/4" liner for the bore, you would not get much noise because there is too much volume in the bore. At this point, since the external pipes are not pressure containing, water pipe is OK.

So how can we make this work? Assuming we went with the 3/4" lliner, we could add more powder, except the 12 gauge blank pretty much fixes the amount of powder we can use. So next, let's think about reducing the volume of the bore. A normal shotgun barrel is 28-30" long, although there are a few that may be as much as 36" in length. But since we are looking for noise, a shorter one is desirable, let's say 24" for the sake of discussion. Now the muzzle of this 24" barrel has to be at the muzzle of the 8' long composite tube or we are back where we started with a muffling problem. So let's add an extension to the back of the barrel that will put the muzzle at 8 feet. This is not entirely a bad idea because it makes the short barrel easy to insert in the long barrel. It also gives us a method of firing the primer since we can run a 6 foot or so solid piece through the extension to bop the firing pin. All we need is a simple breech mechanism to close the chamber and contain the firing pin.

I can let you finish this or can finish it if you wish.

Victor3 · « **Reply #9 on:** September 17, 2012, 12:02:25 AM »

If I wanted a cannon this large just to make noise, I'd go with a propane setup. Lots of plans online and there's no need for a thick-walled barrel.

Cat Whisperer · « **Reply #10 on:** September 17, 2012, 01:05:03 AM »

Quote from: Victor3 on September 17, 2012, 12:02:25 AM

If I wanted a cannon this large just to make noise, I'd go with a propane setup. Lots of plans online and there's no need for a thick-walled barrel.

With propane you can easily get it so loud that your ears will bleed. (and eyes and nose).

sterling · « **Reply #11 on:** September 17, 2012, 01:31:27 AM »

alot of good info here..

this is kinda the breach idea im going to do. http://www.cannonsusa.com/customachining.htm

sterling · « **Reply #12 on:** September 17, 2012, 02:16:17 AM »

wanted to add that the person that is making use the shells is adding a 2" of powder to the shell so the total lenth of the shell would be between 2-4" that should help with the noise effect.

the breach and hammer pin will be done similer to the link i posted above.

GGaskill your statment (It is my guess that a 12 gauge blank fired in an 8 foot long by 5.5" diameter bore will make virtually no external sound since there is so much volume in the bore it will act like a muffler. Even if you were to use a 3/4" liner for the bore, you would not get much noise because there is too much volume in the bore)

3/4" liner do you mean bore size?

thanks for all your input.i am taking everyones seriously.

flagman1776 · « **Reply #13 on:** September 17, 2012, 02:49:32 AM »

I see nothing wrong with the cannon in the video... not my style at all... but safe enough. I totally agree with what the others have correctly pointed out that proper seamless tubing or solid stock of correct steel is a must.
There is a lot of machine work in the breech. Member Powder Keg has his build posted. The photos of the machining will help your machinist.
http://www.gboreloaded.com/forums/index.php/topic,89150.msg1098253470.html#msg1098253470
http://www.gboreloaded.com/forums/index.php/topic,94807.msg1098263197.html#msg1098263197

sterling · « **Reply #14 on:** September 17, 2012, 03:47:24 AM »

awsome pictures... so lets take that design add another 3 or so feet. then stick that into a 8" diam rolled piece of steel to give the look of bigger breach..would this idea still work? this is kinda what im going for..

http://imageshack.us/f/18/dscf4043t.jpg/

now we r getting my idea accross... thanks guys really good info.

want to be safe and have the looks..

KABAR2 · « **Reply #15 on:** September 17, 2012, 06:54:29 AM »

Quote from: oldsoldja on September 16, 2012, 10:42:37 AM

as kids we shot 12 gauge shells off in 3/4 black pipe, over and over again with never a failure, just dont cap both ends and it wont blow up.

Please remember this is a public forum... "Kids" do view it I hope they don't take your views to heart and try it..... kids get enough bright ideas on their own with out the help of others..... we are about safety here and things like this are ill-advised.

GGaskill · « **Reply #16 on:** September 17, 2012, 10:15:44 AM »

3/4" liner do you mean bore size?

Yes, that is what I mean. You want the expanding gas to reach the atmosphere while it is still under pressure. If the bore is too large, the pressure will be gone before the gas exits it.

sterling · « **Reply #17 on:** September 17, 2012, 10:45:36 AM »

ok i am following you.. just now we have to figure out a way to have the end of the barrel go from 3/4" to 2".to have the effect of a real cannon. or can i get away with a 2" bore...

i will make up another drawing with these dimentions.

any ideas?

will be heading home.catch ya in about a hr..

thanks again

sterling · « **Reply #18 on:** September 17, 2012, 12:59:43 PM »

ok took some of your suggestions and made another template..

GGaskill · « **Reply #19 on:** September 17, 2012, 11:07:29 PM »

That's the basic idea, and you would put the shotgun barrel with rear extension in the 2" bore tube.

Now before we go too far on this, let's make the shotgun barrel part so we can fire a few rounds and see if it is satisfactorily loud. Once satisfied with the sound, then we can build the rest of it.

Victor3 · « **Reply #20 on:** September 17, 2012, 11:26:43 PM »

Quote from: sterling on September 17, 2012, 10:45:36 AM

ok i am following you.. just now we have to figure out a way to have the end of the barrel go from 3/4" to 2".to have the effect of a real cannon. or can i get away with a 2" bore...

You could have the 3/4" ID "bore tube" stop 12" back from the end of the outer 2" tube and center it with a bushing. That way it would look like a 2" bore gun.

Just remember that you're going to have to take apart and clean the internals of the thing every time you fire it if combustion gasses are allowed to leak between the various tubes/parts. Take that into account during the design phase.

I don't think it would be nearly as loud with a full-length 2" diameter bore. Might end up with more of a POOF than a BANG...

sterling · « **Reply #21 on:** September 18, 2012, 07:06:50 AM »

ok so my plan is this..take a 5" diam with a 2" bore 6 feet long..try to cut down the lenth. make a foot long breech to load the 12g shell in and see how that works.. then once completed i can build it up to make it look like a biger gun.

with a 2" wall i should be safe correct?

GGaskill · « **Reply #22 on:** September 18, 2012, 11:22:40 AM »

5" diameter solid round is very heavy and you really need only 3/4" walls over the chamber area, which would be 2.25" OD.

Also, the longer you make the bore 2", the more it will act like a muffler.

sterling · « **Reply #23 on:** September 18, 2012, 12:59:40 PM »

ok so let me do another drawing just of the internal barrel..give me a half hr

sterling · « **Reply #24 on:** September 18, 2012, 01:25:58 PM »

Ok so i have the breech and the internal barrel,then at the end of the barrel ill have a bell shape to secure the end of it to the 5" pipe. i think this will do the trick.the breech will be the full size in the rear and were the shell is inserted that will enter the internal barrel..

also would like to add the breech will be made of solid stock.

thanks guys

GGaskill · « **Reply #25 on:** September 18, 2012, 01:44:08 PM »

You're making progress. But build that last part first so you can verify you will get the noise level you want before welding the whole thing together.

jamesfrom180 · « **Reply #26 on:** September 18, 2012, 02:14:17 PM »

I am curious about the legal issues with this since it will use available cartridges.

I would think that if you could use a single shot shotgun, you could adapt a barrel extension. Using the already available action would give you a trigger, extractor, safety, and positive locking breach. I am not sure how you could adapt the extension but my guess would lead me to offer a really long choke tube essentially an 8' open choke. I would use bushing instead of a flare to align the assembly in the sub bore and the rest is up to you.

Problem would be overloading the shell. You would have to stick to factory blanks. My guess is that if you can modify a shotgun in your jurisdiction this would be legal. I am no lawyer but I have thought about doing the same thing to build a model deck gun. Who knows maybe you need to move up to a 10 gauge. Just some thoughts.

sterling · « **Reply #27 on:** September 18, 2012, 02:24:02 PM »

thanks for the input.. i was thinking of the 12G shell part to. i know if im the one firing the blanks made from a 12 g shell then that would be ok but say down the line we have a person who wants to fire a full loaded 12g shell..then whos to say they cant go back on me for this.. so im thinking of making a shell that will fit right into a 1" bore and is unique to this gun..

Gaskill what part of the barrel would you concider "the last part"?

seams we r on track tonight
thanks

GGaskill · « **Reply #28 on:** September 18, 2012, 03:10:17 PM »

The part that fires the shell and carries the sound to the atmosphere. All the rest is decoration and should be done after the sound producing parts are found to perform as desired.

sterling · « **Reply #29 on:** September 18, 2012, 03:10:44 PM »

so then im going to start ..looking at (DOM) Steel Round Tube

4"OD X 1/2 wall I think this will work...as long as i have the 1/2 wall i should be safe..i want to be overly safe since this will be used for many years.

thanks