Casting Aluminum on cast iron - mortar/cannon

[Lantaka]

Has anyone else tried casting Aluminum around a cast iron cannon/mortar barrel?

[KABAR2]

Hello,

And welcome to the site, I am not sure you would want to use Aluminum in cannon construction, also modern cannon construction uses a

steel sleeve built into Iron barrels, I have seen one post from England where a steel sleeve with a reinforced breech was used in casting with

an aluminum skin,  which would be strictly cosmetic, and the gun itself is the steel part.  Hope this helps answer your question. 

[GGaskill]

I have not done so but I see no problem with casting a cosmetic aluminum shroud around a steel core that is strong enough by itself for the bore (wall thickness equals bore diameter unless you have done the engineering to adequately go thinner.)  An all aluminum barrel is definitely not recommended, even if made from something like 7075.  Aluminum never reaches a fatigue plateau so it will eventually fail no matter how thick.

[dan610324]

I know that there have been some Norwegian reenactors who had some barrels cast in aluminum around an way to thin sleve
at least one of them have had the trunnions broken

I dont want to be close to that one when they fire it

[GGaskill]

As I recall, there has been a thread here that showed a UK cannon with this type of construction with a very nice carriage.

[Cannoneer]

Welcome to the forum, Lantaka. The document below is a review of a muzzle loading cannon accident, but the barrel wasn't at fault it was caused by improper handling of the gun. The cannon that was being fired was made in Russia, and was composed of a steel liner with a cast alloy forming the profile of a period naval cannon. I just posted it here because guns like this are being made and offered for sale. I've seen a few other examples of these cannons on the net, and while I'm definitely no expert on metallurgy, I'd agree with what GGaskill had to say. If there's "a steel core that is strong enough by itself for the bore," I would feel safe firing it.

P. 14: Description of cannon & gunpowder charges.

http://www.maib.gov.uk/cms_resources.cfm?file=/grand-turk.pdf

[Soot]

These guys did it here

[GGaskill]

I think that was the one I was referring to.  However, the liner is way too thin, in my opinion, for a live fire gun even though it probably qualifies under the N-SSA 3/8" liner rule.  It's probably OK for a blanks only gun but not for use with shot.

[Evil Dog]

For a really proper live fire gun I see that Tony has one of his listed in the classifieds.

[Lantaka]

I am just learning how to cast metal, and have a lot to learn.

 

Here is a pic of the current experiment.



Thanks GGaskill for the metal info, and Soot for pointing me to how it should be done.  

[GGaskill]

Equally important with the thickness of the tube walls in the way the bore is closed.  The plug needs to be sufficiently thick that it will not bend so the closure weld will not be stressed both longitudinally and radially.  Usually it should be the same as the wall thickness (same as bore diameter) but in a thin tube like the English one, it should be thicker, at least an inch thick if not thicker, to prevent bending.

[dan610324]

is it sand casting you are doing ??
maybe you could try some simplified lost wax casting
at such low temps as needed for aluminum I would guess that you could use standard plaster of paris

[Cannoneer]

These guys did it here

Thanks for posting this, Soot. This site was originally posted on a thread about the construction of carriage wheels, and I forgot all about the M 1841 that this British group had made.

[GGaskill]

While I have been OK with this, I just noticed the actual title says "Casting Aluminum on cast iron."  I do NOT recommend casting aluminum around a cast iron core.  I think I have said steel when specifying a material for the core and that is what I mean.  Cast aluminum around a cast iron core would add little strength to the cast iron which should have a steel liner by itself.