Good cannon bore size? Need some input

Polar Man

Polar Man

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I am in my second year of machining and my interest in cannons was a large factor in getting into the trade. I have some free shop time coming up before the Christmas break and my instructor is letting me make a cannon (actually, for our end of the year project we are all making them on the CNC, due to my constantly asking him to let me :D) So I will be making two I guess, the first one on the lathe. He won't let us put the touch hole in for liability reasons, but I am sure he won't mind me telling everyone a bit more info on that.:D
I originally wanted to make a golf ball cannon, but have since decided it would be just too big and need too much powder, plus golf balls won't really destroy things like I want them too. :D
.50 lead balls are easily obtained but they are too small for my purposes, I believe. If I could easily get some larger ball bearings I would make the bore that size, say 3/4'' or so? What is a common ball bearing diameter, if anyone knows? (Such as car or truck wheel bearings?)
Any other ideas for my bore size/ammo are very welcome. :)
 
I built one for inch and a sixteenth balls once. We had two DROTT 35's dropped off at the shop to be cut up for scrap and the circle had balls that size. I got two ice cream pails fulland sadly they are all gone now. You would be suprised how little powder it takes to shoot them. I built a mould for lead miniballs after the bearings were gone and they weighed 3000 plus grains and it took seven grains to send them across the yard(200 yards) and 90 grains to send them about 2000 yards. It was alot of fun.
 
I am also a bit turned off about wall thickness for the golf ball, the thing will be over 5 inches wide with the rule I have heard, I think the biggest stock I can get in the shop is 3 to 3.5 inches. I suppose I could drill a narrower powder chamber and get away with thinner walls? The stock in the shop is 1018 or 1020 btw.
 
Polar Man said:
I am also a bit turned off about wall thickness for the golf ball, the thing will be over 5 inches wide with the rule I have heard, I think the biggest stock I can get in the shop is 3 to 3.5 inches. I suppose I could drill a narrower powder chamber and get away with thinner walls? The stock in the shop is 1018 or 1020 btw.
Click to expand...

A thick powder chamber is of little use if the barrel immediately ahead is thin. The pressure curve has a longitudinal dimension to it. I think I would suggest checking out the available molds for Brown Bess muskets which should be in the .70 to .75 cal range. Also it is not difficult to make a nesting mold of any caliber that you want. Do a search for Jeff Tanner molds to get an idea of what I am talking about. My own cannon is roughly 80 caliber with a 2 1/2" breach area for some idea of dimensions
You also need to check out photos etc for barrel taper and shape. That also raises the question of what kind of cannon you want to make; artillery or naval or shore emplacement

cheers mooncoon
 
1020 or 1018 is fine and completely safe, but, with 3 or 3-1/2" diameter bar stock it would look nicer if you keep the bore to .750 +.015.
Get a 3/4" ball mill and make your own mould.
 
There's a big piece of 3'' in the shop that has never been used so it looks like that will be my stock, and there is up to a 1'' ball nose end mill to make my molds, but I like what Al Flipo says about 3/4'', as I will need less lead and the bore won't look too big.
As it's just for fun this one will probably look pretty plain, and I will wait for the cnc project and make a fancier one out of some brass that's set aside for that.
If I have time I may put a taper on it and round some corners, but form turning won't be very easy on the lathe unless I can grind some high speed steel forming bits 1.5'' wide,
which isn't going to happen. :D
I will look into the lee molds as well but I will try making my own molds first, it sounds pretty fun. Would aluminum be ok for the molds?
 
I would make it 1" bore size, if you want a bit of a compromise you could make it 10 gauge bore size, the 10 gauge Federal Foster slugs are 766 grains! :eek: a 10 gauge buckshot can load 18 x 00 size buckshot, so can a 12 gauge X 3-1/2", but you could put quite a bit of buckshot in there I would imagine, I would shudder to think what a custom foster slug in 10 gauge would weigh. :eek:

you have ball nose end mills? excellent! you can make the bottom of the powder chamber nice and round, and possibly the end of the bore size you can have a nice round fillet in there to help it resist stress better - some of the old 19th century cannons had the inside of the barrel bore rounded for better safety. have fun man :)
 
The end mills are only about 6 inches long or so, not going to reach the bottom of the bore unless I make a breech plug for the end, which I don't think I will have time for.
I actually considered this problem of a sharp angle at such a crucial stress zone, (which I knew about from knife tangs) so I will ask my instructor if he has any ideas.
Found this cool video of two guys making some cannon balls, the mold looks like the Jeff Tanner ones someone recommended earlier, I think it would be fairly easy to make. :)
[youtube]oxWwJBdWvNQ [/youtube]
 
Here is my rifled cannon, gives you some ideas.
http://img.photobucket.com/albums/v337/alflipo/Picture415-1.jpg
And some moulds made with a ball mill.
http://img.photobucket.com/albums/v337/alflipo/Picture482.jpg
http://img.photobucket.com/albums/v337/alflipo/Picture537.jpg
 
Ill be going down the same CNC operator route for school soon, luckily I have a basic shop at home so I already have tried a 1" cannon that Im close to getting finished. Ive got another one that I drew up that would fire S/S 2" cased sabot rounds but I will save that project for the summer break. Just wondering since Im no golfer what is the Dia. of the average golf ball and is there a seemless tubing that is close to it?
 
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