I need some help deciding......

[The Shootist]

I just acquired (courtesy of work) a 24" length of 4" shaft stock....Metalurgy unknown....  :?

I would love to make a cannon.   :roll:

What kind of bore could I safely use with....say.... a 3.75" dia. around the chamber area? I would like to either shoot golfballs, or even a patched round like a shotgun slug maybe? :twisted:

Open to suggestions. :wink:

[CU_Cannon]

That sounds like it is about the right size for a half scale mountain howitzer.  I have been threatening to build one for about a year now.  I was planning on golf ball bore with a 1” diameter powder chamber.  

Here are a couple of threads about the 1/4 scale one john pike built.

http://www.graybeardoutdoors.com/phpbb2/viewtopic.php?t=74350

http://www.graybeardoutdoors.com/phpbb2/viewtopic.php?t=74781

http://www.graybeardoutdoors.com/phpbb2/viewtopic.php?t=74679

[Double D]

Simple 3.75 divide by 3 equals 1.25 maximum bore.  Forget patching a cannon ball.  

Get one of the sponsors to whip you up a round ball mould o f 1.2 inch diameter and shot lead balls.

[Santa Dave]

Hang ON!
I understand there is a post coming that will show you how to shrink on a re-inforce!
So then you only need a shorter piece of larger diameter  to build a larger, (louder) cannon.
Dave

[Cat Whisperer]

Shrink fitting is a viable technique, given the right design & materials.

It would indeed be valuable to have a thread or two on the process.

[Santa Dave]

is your lathe long enough?
Size Does make a difference!

[GGaskill]

Sounds like a great piece for a 1/2 scale mountain howitzer.  Search the board for previous threads on the subject.  If you bore it 1.75", you can shoot golf balls or 1 lb spherical sinkers.  The area over the chamber is 3.15" diameter which allows a 1 1/16" chamber according to the 100% rule or a 1.35" chamber according to the 2/3 rule.

Try to find out what alloy the steel is so you can determine if it is weldable.  Welded trunnions are much more firmly attached.

[Double D]

2/3 Rule George?

[GGaskill]

The 2/3's rule for centerfire smokeless cartridge guns.  Wall thickness of chamber should be at least 2/3 of diameter of cartridge.  You mentioned it before yourself.

[Double D]

That's correct George 2/3 for smokeless powder rifle cartridges.  It does not apply for black powder cannons. Different dynamics

The safety rule for Cannons is the wall of the cannon around the breech should be no less than the diameter of the breech thick in all directions. 1 for 1.  

With modern materials you may be able to get away with thinner walls but safety rules of the various cannon shooting organizations have settled on the 1 for 1 rule for safety purposes.  Should you have an accident with a gun made with thinner walls, the lawyers for the plaintiff are going to point to those rules and say you were negligent for not following the established safety guidlines.  

We ain't smarter than those fellows who wrote those rules so we are not going to differ from them on this board.