Author Topic: Is it really safe to make your own cannon/mortar? (Read 2521 times)

entsminger · « **on:** January 03, 2006, 09:37:01 AM »

Well I finally got a copy of Matt Switliks More Complete Cannoneer for Christmas and I have to admit that it's pretty discouraging as far as building a mortar barrel myself. It seems that even the best cannon makers can have problems making cannons right and safe to shoot. Problems with liner leaks, missalined liners ,vent hole trouble, wrong casting material,assorted casting problems etc etc are just a few of the problems that plague many cannon makers. and this is from folks who have been in the business to make cannons. How is some well intentioned guy in his home shop with a lathe/welder and a chunk of iron and a little milling skill ever to make a safe cannon?It seems that alot of folks have made really cool and apparently safe firing cannons on the Forum and seem to know an incredable amount about cannon building. Lots of folks have built their own cannon and they seem to fire them ok. Some good old boys in Wisconsin have made a 10 inch mortar in their own shop and shoot it in competition alot with no problems? These home builders are smart but I doubt they are any kind of certified cannon experts? Are they just lucky that problems didn't occur? Maybe I'm wrong but it just seems from what I'm reading that even the very knowledgable can run into serious life threatening trouble when making a cannon. After this book I'm getting the feeling that cannon building is something better left to some kind of certified cannon building specialist/meturligist expert? Am I over reacting? Maybe this book has scared me and it really isn't as difficult as it seems?
Now I don't even know if a mortar that I bought would be safe? It seems that liners are a must yet I don't think the great Paulson Brothers mortars have liners and their mortars are highly rated? Hearns and other mortar makers say they don't intend their mortars to be shot even though some people shoot them. I had hoped this book would help but frankly I'm really feeling lost .

Scott Springston

jeeper1 · « **Reply #1 on:** January 03, 2006, 11:25:55 AM »

Quote

Am I over reacting?

I would say a qualified yes.
If you are dealing with a cast barrel then it had better have a seamless liner with a welded and pinned plug in the chamber end or it's for looks only.
If you are talking about a drilled and reamed bore in a non-cast barrel such as 4130 or 4140 if there is enough wall thickness then I don't see a need for a liner. I consider enough wall thickness to be a minimum of 2/3rds the bore diameter.

Tropico · « **Reply #2 on:** January 03, 2006, 01:36:26 PM »

If you are versed in the New York Times .,then you know yourself .,"You cannot believe everything you read"

It is very likey the writer of the book hasnt tested every calliber.,metal alloy.,load.,or any other combination of these known to man.

Thats one mans take on it (mine).

Consider the Cannon and Black Powder has been around a very long time. There seems to be some basic s on the "Rule of thumb" . This forum seems to keep to the idea of a wall thickness greater than or equal to a bore diameter is a safe measurement for a build. That sounds pretty logical and safe . Then there is always the start with small loads and work up a bit. Then there are people on the board who will help you with knowledge of alloy types that are available in todays world.

I have heard of cannon failure tho I have never seen it.,and we have fired alot of stuff. I believe it can happen I also believe its near impossible with just a little common sence and buffed barrel., Its like youd have to be trying to cause damage.,over loading and getting extreme. Its hard to break apart a 2" steel wall thickness., when its easier to push a wad of newspaper out of an open hole. "The physics claim the bore is the easiest way-out"

I am no expert but I have a few in my collection and I feel very very safe when they go boom. Consider this a 30-06 has a thin brass wall cartridge loaded in a steel pipe (Barrel) and its got a pretty large amount of hot gunpowder in it and that can handle its blast fine. A cannon is pretty safe.

Hope this helps and dont give up on your cannoneering !!

Cat Whisperer · « **Reply #3 on:** January 03, 2006, 01:57:32 PM »

My philosophy of cannon design is to take one of two approaches:

1. Have it engineered by an experienced metalurgist/mechanical engineer with experience in the field.

- or -

2. Copy the design of one who's made cannons for quite some time, understand and use the principles of design to the best of your ability, and overbuild it a bit from there.

Not many of us fit into the first category, but all of us can make or have made reasonable copies of good designs.

Making a good decision and not taking shortcuts is important.

USING it REASONABLY is also requisite.

It can be done. It can be done safely.

GGaskill · « **Reply #4 on:** January 03, 2006, 02:13:25 PM »

Considering that the USS Missouri could launch a 2700 lb shell 16" in diameter and it was designed in the late 1930's, launching a 60 lb 13" spherical shell from a mortar less than 4' long should not be too much of an engineering challenge.

The problem we are facing is that most home made artillery is not engineered. At best some rules of thumb that have worked in the past are applied to the project. Fortunately most of those rules are very conservative in nature. Also, many home made pieces are copies of successful designs of the past but are made from stronger materials than the originals. This gives an additional margin of safety.

Most of us do not have unlimited budgets to spend on our artillery, so we try to minimize the cost of materials and labor, including the use (more accurately, the non-use) of professional designers. Budgetary constraints tempt people to use inadequate materials, such as galvanized water pipe. Most of us answer the money issue by making subscale pieces, 2' long Napoleons (1/3 scale) instead of 6' long ones. (This reduces the size of the machinery needed, also.)

But we must face the fact that the shooting sports are expensive to participate in. Maybe you need to scale your desires to your pocketbook.

Cat Whisperer · « **Reply #5 on:** January 03, 2006, 03:26:25 PM »

Scott - You owe it to yourself to read through this thread from the beginning to the end. It addresses a lot of issues - one at a time - and the solutions.

http://www.graybeardoutdoors.com/phpbb2/viewtopic.php?t=13760&postdays=0&postorder=asc&start=0

Watch the emotions go up and down. Note that the issues of casting were sidestepped and the solution tailored to the equipment and skills at hand.

We all start SOMEWHERE. We all (hopefully) learn and move on to more advanced projects.

kappullen · « **Reply #6 on:** January 03, 2006, 05:27:14 PM »

Cat,

That's an interesting old string by Miss Jane.

I may have packed the liner with dry ice, and alcohol,
and bet she would slipped right in.

We used to assemble extrusion dies, shafts in hubs, and
other stuff that way.

I know what she is saying about creaping. We had that problem too.

Kap

Double D · « **Reply #7 on:** January 03, 2006, 07:13:33 PM »

Scott,

Glad you liked the book. Don't let it scare you let it lead you.

As you can see from the book there are those who know how to make metal objects that look like cannons and then there are those who know how to make cannons out of metal.

There are a couple of those types listed on resource list. When you contact a cannon maker especially if you are looking at a cast iron tube ask them about their liners. Is it seamless. If they say no then they don't know how to make cannons.

Double D · « **Reply #8 on:** January 04, 2006, 04:49:01 AM »

Quote from: jeeper1

Quote
Am I over reacting?

...If you are talking about a drilled and reamed bore in a non-cast barrel such as 4130 or 4140 if there is enough wall thickness then I don't see a need for a liner. I consider enough wall thickness to be a minimum of 2/3rds the bore diameter.

This is very interesting and I had never thought of it this way before. The rule of thumb for high pressure rilfe barrels is that the cylinder over the chamber should have walls that are no less than 2/3 the diameter of the chamber thick. In cannons the safety rules of N-SSA and AAA call for the walls of the cannon to be one caliber thick over the breech.

Now most of the guns they are talking about are cast guns with lined bores. But with a barrel of 4130 or 4140 I can see only one reason why 2/3rds wouldn't be acceptable; you wouldn't be able to shoot it in N-SSA or AAA shoots.

Scott I believe you live here in Northern Virginia. I'm in Herndon. You have easy access to Winchester and nearby Ft. Shendoah. Go out there and and watch them folks shoot their cannons. You will find some friendly elbows to rub out there. Drop me an email and maybe you can come over and look at the 6PDR mortar I am building now and get some idea about the logistics involved in working with this mortar.

I know you have your mind set on a full scale Dictator. But the shear awesome size of that mortar makes it a whole lot more gun than a beginner should use. It will take a days pay just to fire it one time.

I started with a popcan mortar. It was made from a piece of steel shafting used to make propeller shafts on sea going tugs. When completed it weighed close to 100 lbs. It was a handful. I had a teenage son who I fed regular to help. When I built that mortar I had me eye on building a 8 inch. Well I have toned that down a lot since then. A bowling ball mortar will be just fine for me now.

entsminger · « **Reply #9 on:** January 04, 2006, 04:56:41 AM »

Thanks for the responces. No I haven't given up on the idea of building my own cannon yet it's just that after reading about all the intricacies of making a barrel safe and correct that it just seems that that kind of work might be better left to the professional? I really need to see for myself how some of these guys make cannons like the family in Wisconsin who made their own big mortars in their own shop. Then I could see in person how far fetched it may be for me to even contemplate doing it my self. Wisconsin is a long way from Va. though.
Scott

Double D · « **Reply #10 on:** January 04, 2006, 08:40:23 AM »

Yeah but New windsor MD isn't that far. Why don't you go visit Cannonsonline.com they make cannons in your neighborhood.

guardsgunner · « **Reply #11 on:** January 04, 2006, 09:34:12 AM »

DD
A barrel machined from solid steel can be Approved in the NSSA. A steel liner in a steel barrel would be just silly unless that is how your rifling is goin in.

entsminger,
Call and talk to Antique Ordnance Publishers or the Paulson Bros. if you are serious about a 8" mortar. Ask If they know where you can get one cast and then call them. I am pretty sure they would give you that info. or at least clues. Might order the info book (around$10)and see what kind of work your looking in building that carriage. It wont be that easy either.
Most figue around 4-5 years to complete full scale stuff at home.

Cat Whisperer · « **Reply #12 on:** January 04, 2006, 12:15:51 PM »

Quote from: entsminger

Thanks for the responces. No I haven't given up on the idea of building my own cannon yet it's just that after reading about all the intricacies of making a barrel safe and correct that it just seems that that kind of work might be better left to the professional? I really need to see for myself how some of these guys make cannons like the family in Wisconsin who made their own big mortars in their own shop. Then I could see in person how far fetched it may be for me to even contemplate doing it my self. Wisconsin is a long way from Va. though.
Scott

Good approach, Scott.

It's a task to weigh your own skills (and motivation) against paying someone else to do the job.

I still change my own oil and spark plugs - except for the Ford - those back three are WELL worth paying someone else to change.

How about a week's vacation this summer in Wisconsin ? I've spent two 4-month summers at Fort McCoy and enjoyed every minute of it. Good people, good food and good beer. (The classic picture of Paulsons' 13" seacoast mortar being fired was on range #10 of Ft. McCoy.)

Double D · « **Reply #13 on:** January 04, 2006, 07:00:30 PM »

Personally I still think your orignal idea Scott using that old LPG tank is workable.

Ever since you first mentioned it, I have been thinking about it.

Build a straight sided mortar tube with the proper mortar size powder chamber for 8 or 10 inch ball. The diameter of the tube wouldn't have to be that great because the powder chamber wouldn't be that large. Say 9 inch Seamless for the 8inch and 11 inch for the 10 inch. The tube by its self would be heavy enough by itself to be a stand alone cannon.

Weld a flat plate over the front with a hole for the tube. Add trunnions to the tank. The trunnions probably should go all the way through and attach to the tube.

Turn the round end up and through a opening in the round end fill the whole thing with concrete.

Every thing from the Inner tube out would be nothing but decoration.

GGaskill · « **Reply #14 on:** January 04, 2006, 09:00:08 PM »

The major problem I see with the concrete is that it will add about 4600 lbs of weight to the barrel, which already will be pretty heavy from the steel alone.

I think you can make a Dictator simulator by making some concessions in charge weight and shot weight. But it is not going to be a low budget project. Even 55 lb hollow aluminum shot are going to cost over $100 each.

Cat Whisperer · « **Reply #15 on:** January 05, 2006, 01:31:15 AM »

Quote from: GGaskill

....
I think you can make a Dictator simulator
....

THERE's an idea!

You could make the thing from the end of the propane tank, skip the concrete. Use a 1/2" thick wall liner open at the bottom.

Fill the inside with an air-propane gas mixture and ignite with a spark plug.

The flame alone should go 100'. THe report should be heard half-way across the state!

Of couse, then, you'd have to have a safety zone of 500 meter radius so you don't scorch everyone's whiskers and make their ear-drums meet in the middle.

entsminger · « **Reply #16 on:** January 05, 2006, 02:25:23 AM »

I'm still going to make my big propane tank into a 13 inch mortar . Actually it will be slightly under 13 inch more about 12 and 1/4 inches as the tank is really only 41 1/2inches diameter where as the real dictator was 43 inches in diameter. Folks have pretty much convinved me the size difference would not be noticed so I have "sort of "shelved the idea of enlarging everything a little to be exact size. I'm also still considering making it shootable but I still haven't figured out yet if it's feasible or safe to do yet?It would be cool though!
Aside from that I am also just trying to see if it's possible to ever build or buy a 10 inch mortar so that I could have something to cart around to Skirmishers shoots or just sit in the yard an look cool.
Yup, these will be very long term projects. It took me 3 years just to arange and get my propane tank from Pennsylvania to Va. Another year to get the 12 1/4 inch barrel pipe and scrap steel for the face, Still looking for some 15 inch pipe for the trunions.Not alot of junk yards in the Washington area like there used to be.
I have contacted Cannons online at least twice about seeing their facility but they always say not now but give us a call in the future to set up a date. I have pleaded with my wife to possiblly go to Wisconsin in the summer to see the Frederickson shop and Paulson Brothers sometime but haven't been given the green light yet.
It is fun at least to be thinking and talking about building cannons. My friends look at me like I'm nuts and maybe I am. We go to Ft. McHenry in Baltimore now and again to drool at the 15 inch Rodmans. Believe it or not they have another bigger propane tank that is just about the rodman size in Penn.that I may try and get in the distant future to try and make a into non shootable 15 incher. Wouldn't that be cool aiming at the new McMansion they just put up next door!! That would just require some 15 inch pipe and alot of scrap and welding which I pretty much think I can do.
I thought I was crazy and then I talked to this fellow in Penn. who actually scuplted and then poured a full sized 13 inch mortar out of conctrete and had a steel carriage made at a school shop. It sat on display and looked really good till it got hit by a truck and broke to pieces.He was going get a tank like mine and make one himself after I told him I got mine and he was going to help me work on mine and we coresponded regularly but then he suddenly stopped responding ? Maybe he died or his computer crashed, or his wife said stop dealing with this cannon nut, I don't know? I wrote to his address but get no responce? Can't seem to get ahold of him now for anything. I also used to relic hunt for cannon balls 20 years ago and now have a site that might produce a few 100 pounders if we are very lucky. I've found about 30 cannon balls/shells over 30 years of hunting. Anyway, I think by now you can see I am sort of obsessed with cannons to some degree.

Scott

Double D · « **Reply #17 on:** January 05, 2006, 02:28:11 AM »

Quote from: GGaskill

The major problem I see with the concrete is that it will add about 4600 lbs of weight to the barrel, which already will be pretty heavy from the steel alone.

Will it add 4600 lbs in excess of what the tube would weigh it it were cast iron?

The Shootist · « **Reply #18 on:** January 05, 2006, 04:22:58 AM »

If cast out of concrete, or to make them lighter... turned from wood. Even a concrete casting with a lighter core would work.

After all, you're not trying for a full-sized powder charge.....

GGaskill · « **Reply #19 on:** January 05, 2006, 02:18:56 PM »

Will it add 4600 lbs in excess of what the tube would weigh it it were cast iron?

No, the 4600 lbs is on top of whatever steel pieces would be used. A cast iron original weighs on the order of 17,000 lbs.

Fill the inside with an air-propane gas mixture and ignite with a spark plug.

Now that is an interesting idea, although I would substitute gasoline for propane. However, we come back to the issue of what kind of pressure is produced (still thinking of launching aluminum shells), and now the thin propane tank outer shell has to resist the pressure instead of the thick powder chamber/breech block.

According to my Cylinder Stress Calculator, with an ID of 40", a wall thickness of .25" and a chamber pressure of 1000 psi, the stress is 80,000 psi which is way too high for my comfort.

GGaskill · « **Reply #20 on:** January 05, 2006, 02:31:05 PM »

Former duplicate. We were experiencing timeouts again.

GGaskill · « **Reply #21 on:** January 05, 2006, 02:35:24 PM »

Cat Whisperer · « **Reply #22 on:** January 05, 2006, 02:55:46 PM »

From the artillary simulators I've seen, a gas chamber of 4" x 24" would be plenty. Also, the wall thickness on them was less than 1/4". It was a simulator for a 105mm tank cannon fired by propane and air.

A friend, who ran a cannon shop in Cedar Rapids, IA, used it on request for something that would make a lot more noise than the cannons used previously. Tremendous success. His wife did tell him to look in the mirror on his return - blood flowing from eyes, ears, and nose. Maximum fun in total disregard for safety!

GGaskill · « **Reply #23 on:** January 05, 2006, 02:59:07 PM »

I expect as a noise and fire maker ONLY, it would be OK, but I am still talking about launching shells from it.

But with a barrel of 4130 or 4140 I can see only one reason why 2/3rds wouldn't be acceptable; you wouldn't be able to shoot it in N-SSA or AAA shoots.

If you are making copies of traditional ordnance, the proportions will give you greater than 1:1 wall thicknesses. Only freelance designs would potentially be less than 1:1.

Scott--how long is your piece of 12 1/4" pipe?

entsminger · « **Reply #24 on:** January 06, 2006, 02:20:04 AM »

I have Two 12 1/4 inch pipe sections. They are only 1/4 to 3/8th inch thick though and I'd guess they are not seamless. Just some pipe I got at a junk yard. One is about 5 feet long the other about 4 feet long.Good for looks only I'm sure. For shooting I'm still thinking the barrel pipe would need to be plenty thick to safely fire a aluminum ball. Several inches thick at least I would guess? I'd rather error on the too strong side than too thin. Where to get or what a piece of seamless 12 1/4 inch diameter 3 or 4 inch thick pipe would cost I have no idea?? Probably as much as a 10 inch mortar? Maybe I need to find an old battleship barrel, cut it to length and stuff it in my tank,ha ha...I talked to a friend who lives in Va Beach who has a relative who works at the war ship scrap yards in Norfolk Va. but they could find no scrap barrels at this time. I still need to call George G. and talk about this someday.

Double D · « **Reply #25 on:** January 06, 2006, 05:20:51 AM »

Quote from: entsminger

For shooting I'm still thinking the barrel pipe would need to be plenty thick to safely fire a aluminum ball. Several inches thick at least I would guess?

No not really. The mortar is a two diameter barrel. The powder chamber is smaller than the bore.

The barrel over the chamber needs to have walls at a minimum the same thickness as the diameter of powder chamber.

The barrel portion where the ball goes is an expansion chamber and projector tube. The walls in this area do not need to be as thick. With the steel plus surrounding filler of concrete in cased in the outer steel tank.will have plenty of strength. in that area.

If you build a barrel with a 11 inch OD and a bore of 10 inch, you could have a powder chamber of 3.666 diameter. Keep in mind in addition to surrounding the steel bore section, the concrete in cased in the steel tank will be surrounding the chamber adding a additional strength.

Quote

...I talked to a friend who lives in Va Beach who has a relative who works at the war ship scrap yards in Norfolk Va. but they could find no scrap barrels at this time. I still need to call George G. and talk about this someday.

Make sure you report back to the board on this, we will all be headed to the scrap yards right after your announcement.

Quote

But with a barrel of 4130 or 4140 I can see only one reason why 2/3rds wouldn't be acceptable; you wouldn't be able to shoot it in N-SSA or AAA shoots.

If you are making copies of traditional ordnance, the proportions will give you greater than 1:1 wall thicknesses. Only freelance designs would potentially be less than 1:1.

George the point was that N-SSA and AAA rules do not appear to allow a barrel with a wall thickness of less than one breech caliber over the breech even if made with something like 4130 or 4140.

Your note on the ratio is interesting however, as it appears that original designs built in a safety margin. Good point.

guardsgunner · « **Reply #26 on:** January 06, 2006, 08:23:29 AM »

DD,
Coehorn mortars were the only ones to have a powder chamber at the bottom. 8" and up have a slight narrowing of the rad. under the shell and no chamber.

Double D · « **Reply #27 on:** January 06, 2006, 12:04:09 PM »

That's only partially correct. The 1861 8 inch siege mortar doesn't have a clear chamber rather an ellipsoid that is smaller than the ball. The 1841 has a trapazoid shaped chamber whose wide side is the diameter of the ball. The 10 inch seacoast Model 1844 has a definite chamber.

But for Scotts mortar I am suggesting a chamber that is 1/3 the total diameter of the inner steel barrel.

The concrete is nothing more than a filler betweeen barrel and outside tank and is there to add bulk and mass. The inner barrel is the cannon and will contain the pressure. Concrete isn't compressable and being "sandwiched" between the barrel and outer tank shell it is going to contribute to the total strength by way of the theory of lamination. The concrete only has to resist the pressure transmitted on the ouside of the barrel not the inside.

guardsgunner · « **Reply #28 on:** January 06, 2006, 02:16:50 PM »

Sorry DD,
I couldnt think of a better way of describing the 8" as a narrowing of the rad. without spell check :grin: . The 8 ,10 and 13 (seige)are all the same in 1861. (have loaded the 8's many times.) I had forgotten about the earlier heavies.

Double D · « **Reply #29 on:** January 06, 2006, 03:22:25 PM »

I thought you would think that I'm pretty smart knowing that word....but I must confess...it's on the plans.