There is quite a learning curve to 3D printing, and most of my prints so far have exhibited considerable room for improvement. There are some helpful YouTube videos on the subject, but at my beginners level there is still a lot of trial and error.
I am still planning my next cannon model build, and printed some cannon barrels to improve my printing skills, and also to have a plastic model of the barrel to help decide about construction methods of the metal model.
The next prints took 22 hours (vertical orientation) and 24 hours (horizontal orientation) each.
Firstly the vertical orientation..
The next print was horizontal…
Now I am ready to turn the barrel in steel. I have obtained a facsimile book about naval artillery which was written in the late 19th century, it reveals that the Armstrong barrels were made in concentric pieces, and heat shrunk together. I will adopt a similar method, making the cascabel and the central rifled tube separately from the breech sections. Not decided whether to heat shrink them together, or silver solder, or Loctite. (ps. a week later. Changed my mind. Making the barrel from a single piece of steel)
The artillery book also answered my question about 64 -80 lb cannon and bore sizes. When round shot was replaced by pointy cylindrical projectiles, the projectile weight could increase by increasing the length rather than the diameter of the projectile. And some 64lb cannons were redesignated as 80 lb cannons, after modifications which did not necessarily alter the bore. Unfortunately the book does not answer how the rifling was accomplished with a closed breech.
And I made another workshop tool. This one is a lathe tool height gauge.