Cannon proportions

[NitroSteel]

I'm wanting to make a perfectly scaled civil war field cannon (wooden carriage).  What I have to start with is a 30 mm rifled barrel and want to build everything else around it.  It is about 2-1/4 inch OD on the thickest end and about 33 inches from there it is about 1-7/8 inches.  From there it steps down about 1/8 inch and then is tapered similarly to the muzzle (about 6 ft total).  I was thinking of cutting the barrell to about 33 inches, but want to make sure that it is proportioned properly.

The reason I was thinking of cutting it at the "step down" was to use the thinner muzzle end of the barrel for a HUGE muzzleloading rifle, that would leave 42 inches for it.  I will initially be shooting lead balls and may later have a mold made for conical bullets.  The cannon portion of the barrel is most important to me, even if I have to skip the rifle idea all together.

How long should the barrel be based on this diameter OD?  How big should the wheels be?  I am getting ready to get started...

Thank you,

Nitrosteel

[seacoastartillery]

     First, answer 3 questions, then quality suggestions can be offered.

         1.  Do you have machining capability, lathe and mill?

         2.  What type of CW piece do you prefer to build, field gun, naval gun, siege gun, or seacoast gun?

         3.  All CW tubes are shorter than modern artillery for any bore size you can point to, so you will have to pitch a good portion of that 30mm tube, about half. 

     Right now, assuming you have a lathe or access to one, it looks like the  4.5" U.S. Iron Siege Rifle, Pattern 1861  looks like it has the longest tube per bore diameter.  This would be approx. a 1/4 scale because your tube has a 1.181" bore diameter.  This big rifle was 133" long which makes a 1/4 scale piece 33.25" long.  This was one of the heaviest siege rifles on the battlefield and has a large wood siege carriage.  What do you think?

Regards,

Tracy and Mike



     

[Double D]

First figure out which gun you want to build, then find your self a set of plans for the gun. We can tell you where to find plans. Using the major diameter of the tube you have and the major diameter from the plans figure out your scale.  Then scale out the length you will need.  Check the diameter at that length of your tube and see if it matches the scaled diameter of the plans.   If it matches or is very close, go for it.  

But you have another problem with that barrel .  As it is the barrel walls are too thin for safety standards.  A 30 mm bore needs to be 90 mm over the breech.  90mm is just a shade over 3.5 inches. No big deal just shrink a band over the breech to bring it to size, then do your scaling.  What ever gun you build you are going have to factor in this safety standard.  

Here's a copy of my plans for a Parrot rifle to demonstrate what I am talking about:




The major diameter of the plans is 2.75 inches.  You barrel with band will be 3.5 inches.  Divide 3.5 by 2.75 and you get a scale factor of 1.27.  Multiply every measurement on that drawing by 1.27. Length in the drawing is 19.5 inches times 1.27 give a length of 24.82 inches.  The diameter at 24.82 inches the muzzle is found by multiplying the muzzle diameter in the drawing 1.5 inches by the scale factor of 1.27 or  1.905 inches

So you need  a section of barrel 24.82 inches long that is no smaller than 2 inches in diameter.


There is one other thing you could do.  Turn this barrel cylinder and use if for a barrel liner in say a cast iron barrel like sold by some barrel makers.  All depends on how much work you are willing to do

[GGaskill]

As the owner of several pieces of demilled 25 mm and 30 mm barrels, it is my opinion that making a scale model of a Civil War era cannon using the profile of the barrels as made is not practical.  However, using them as rifled liners would work, assuming you have the tooling to drill the hole in the exterior portion of the barrel.

[NitroSteel]

seacoastartillery:

1)  I have a friend at a machine shop that can pretty much do anything (I think), reasonably inexpensive
2)  Field gun probably
3)  Sounds perfect

Double D:

I DO plan on shrinking a 3.5 - 4" band over the tube for safety

GGaskill:

I understand your point.  But I'm not sure that I (my connection) has the capability of doing what you suggest in order to make the barrel I have the liner, and then inserting it into an exterior tube for the exact profile.  The last time I tried to get him to do something like this to a piece of length, he balked.  I don't think it was that he "couldn't" do it, I think maybe he just knew that it would be very time consuming (right?) and that it would be more costly than what he thought I'd want to pay.  Is this a tough/time consuming job, or does it take some specialized equipment other than a big lathe?  It seems like he mentioned that after a certain length of boring, that the tolerances changed greatly.  Maybe I just don't know what I'm talking about....  That's why I pay.

I am open to suggestions.

Thank ya'll again.  This is BY FAR the best website ever created.

NitroSteel

[GGaskill]

I would do the process by drilling the bore for the liner with conventional drills, either twist or spade.  The goal is to get most of the material out of the way.  Then I would ream the hole to the diameter of the liner plus a few thousandths (depending on what the requirements of the Loc-tite of choice are.)  To save the cost of a custom sized reamer, I would pick a standard size one and turn the liner to the proper clearance.  The reamer will size the hole accurately. 

The disadvantage of drilling a deep hole is that the drill usually doesn't stay exactly in the center of the bar, so you could end up with a curved hole or one that is off center at the breech end.  If this is a concern, the hole could be drilled undersize and bored for position before being reamed for size.

Your friend is right; deep hole boring is not a really accurate process because the boring bar becomes too flexible at the lengths involved.  Still, the hole could be reamed to size after boring and you would get the location advantage of boring along with the accurate hole size of reaming.

[Victor3]

 NitroSteel,

 One option for using your barrel as a sleeve is to have it turned to a diameter that would slip into a seamless steel tube. The benefits of this type of construction are:

 1. There's no need for deep-hole boring.

 2. You'll know that the material of the outer sleeve is able to be welded (for trunnions, etc).

 3. You can have the outer tube machined to whatever custom profile you want.

 4. It will likely be less expensive than most other options.

 5. Properly done, it will be very strong and safe.

 One of the sponsers here makes his barrels from seamless steel tubing at very resonable prices. He may be able to help you with your project if you decide to use this type of construction.

[GGaskill]

One thing to consider if you use seamless tubing for the outer layer is that the hole in seamless tubing has a fairly large tolerance on diameter and straightness.  You may have to take special precautions in joining the two tubes.

[Victor3]

One thing to consider if you use seamless tubing for the outer layer is that the hole in seamless tubing has a fairly large tolerance on diameter and straightness.  You may have to take special precautions in joining the two tubes.

 While I agree that most suppliers' standard tolerances for seamless tubing are somewhat generous, the diameter and straightness (in my experience) is always very consistant end-to-end in any one piece of stock. I would certainly want to have the particular material in-hand, and would turn the rifled sleeve to fit...