As part of my 24-Pounder Naval Gun model project, after laying out the pattern onto a 2 inch piece of bar stock, I decided to turn down the the final dimension for the bulk of the barrel.
The choice to take this step is predicated on the next steps in my order of operations. Before I can drill out the barrel, I need to bore in a trunnion hole. The trunnion is the pivot for the barrel, and the hole will allow the trunnion to be run through the barrel. Once the trunnion is epoxied in place I will drill out the barrel.
Also, considering that I do not yet have a ball turning tool for my South Bend lathe, I do not yet have all of the tools required to finish the model.
So, I left the muzzle material in place and simply turned it down to approximately 1.5 inches. I am going to leave this material in place to mount the barrel in a steady rest in the future. Next, starting with the first band from the muzzle, I turned down to just over the final dimension. Once complete, I remeasured and started to define each barrel bande. Then remove the material between each strengthening band along the length of the barrel.
Tapering the Barrel
Once all of the bands are cut down to their final dimension, I profiled the barrel. The 24-Pounder is an interrupted 3.8 degree taper along the entire length of the barrel. As I do not have a taper attachment, I opted to use by compound slide to make this cut. I adjusted, to the best of my ability to set the compound slide at 3.8 degrees. The protractor on the slide only allows indexing and 1 degree increments, so I set this as close as I could.
After I had the barrel cut down to close to the final dimension. At this point, I broke out increasingly fine sand paper and proceeded to start the polishing process to remove some of the tooling marks.