I have amassed a number of cannon and mortar and one I really was hoping that I'd get out bid on on Ebay I ended up winning. For the rest of my stuff I have three bore sizes: 1/2", 1" and Golf Ball size. The cannon I won the bid on was a miniature copy of the Confederate Dictator siege mortar and the guy did a very good job on all parts concerned including the barrel. But it's bore took an .820 round ball? Kind of out in left field there. So my son is a machinist and in always interested in my gun/cannon projects so I made a steel plate (two of them actually) that held sixteen .820 round balls in a square. Stacking up the next level was nine the four then one for a four sided pyramid like they did in the Civil War (although a lot of three sided pyramids are seen in old pictures, the math was too hard for me so four sided it was). He was tickled pink and put the mini cannon balls and siege mortar on display at his house.
Well, last weekend he came up for a visit and said that he had something for me. It was a home made cannon and base that he whipped up from scratch during his break and lunch times. All the CNC machines were spoken for so on a standard lathe he cut a 45 on the breech end and then kept changing the angle of the cut to put more angles at the breech end of the mortar. After creating several cuts on the breech end he finished the radius with the cannon turning in the lathe and use of a standard bastard file. It came out smooth as butter. After creating the outside radius of the breech end, he then knew how far to make the bore and was able to radius the inside of the bore with hand ground boring bits. The outside of the barrel was then turned with barrel rings being similarly file radiused and finally dipped it into some black oxide to color the barrel like an aged patina. The nuts he used for the carriage bolts were home made as well with their four sided finish and black oxide coating. Brass made the bolts and trunnion caps. He at first made the trunnions extra long from a top dead center blind hole and threading. To get 180 degrees on the other side for the opposing trunnion he made a jig that held the first trunnion perfectly vertical and was able to measure and find the top dead center of the other side. Sorry I don't have pictures, but he did an absolutely amazing job for having never constructed a cannon ever in his life. I hope that this interest continues as I'm sure that he'd be quite good at the craft with his clever mind and experience as a machinist. Smithy.