The Home Machinist!

I have just got the plans for a model cannon based on those of the USS Constitution 1779. These are marked "model only" but I intend making it so it does fire black powder. The only part that concerns me is the trunnions, these are shown as drilled into the body of the cannon which is fine if you don't intend shooting it but as I am intending shooting it I was thinking of silver soldering them on so as to leave the barrel intact. Does anyone have any experience with this sort of thing? Any advice would be appreciated. I am making it out of brass.
Thanks
Clive

i don't know the caliber,size ,rifled or smooth bored. but i would key the trunions to the barrel out of a desire for increased
strength. i have done this on a couple larger one that were built.

i would be very carefull about my alloy and even think about steel.

Hammermill, When you say "keyed" do you mean drilled and tapped? This is my concern - removing metal from the barrel. The trunnions in the old cannons were part of the casting. As it is a model, with overall length of 12" and a smooth bore of .563" there won't be a lot of work on the trunnions as the wood is fairly lightweight.
Clive

think of a dovetail as you would see on a pistol sight or consider a ring around the trunion area and the trunions set in it. this would not be authentic, originals were all one casting

Yo!. I have made cannon from round stock of .45 cal that shoot .44 cast lead ball. I made a ring that held the trunion pins and sweated the whole together with silver solder.

I am averse to drilling the side of a barrel, although I have done one that way. A mill makes a mark and drillls down about 1/4 inch for a brass turned pin. The pin has a collar slipped over it to match the curve of the barrel, for a seamless look. Again this is silver soldered.

I have also cast barrels from scrap bronze, breach down, so if there is shrink and porosity, it winds up in the middle of the barrel, and is mostly drilled out.

Much depends on the charge you shoot. 40 grain is about the right load for a .45 cannon. 60 is too heavy, and will be a short range rifle load with 3fg. Use fg, or 2fg, for slow burning. 4fg pan powder is too fast, and worse if under loaded, as it will 'snap' harder before the ball moves very far in the barrel.

All things considered, shoot from a heavy mounting board, so your cannon can be tied down, as the recoil can be considerable without all the real weight there. I have to disavow any appoval on shooting homade cannon, guns, or other contraptions, with any propellant, as the result can be dangerous, and unpredictable. All safty and range precautions should be followed.

steamin10 wrote:Yo!. I have made cannon from round stock of .45 cal that shoot .44 cast lead ball. I made a ring that held the trunion pins and sweated the whole together with silver solder.

I am averse to drilling the side of a barrel, although I have done one that way. A mill makes a mark and drillls down about 1/4 inch for a brass turned pin. The pin has a collar slipped over it to match the curve of the barrel, for a seamless look. Again this is silver soldered.

I have also cast barrels from scrap bronze, breach down, so if there is shrink and porosity, it winds up in the middle of the barrel, and is mostly drilled out.

Much depends on the charge you shoot. 40 grain is about the right load for a .45 cannon. 60 is too heavy, and will be a short range rifle load with 3fg. Use fg, or 2fg, for slow burning. 4fg pan powder is too fast, and worse if under loaded, as it will 'snap' harder before the ball moves very far in the barrel.

All things considered, shoot from a heavy mounting board, so your cannon can be tied down, as the recoil can be considerable without all the real weight there. I have to disavow any appoval on shooting homade cannon, guns, or other contraptions, with any propellant, as the result can be dangerous, and unpredictable. All safty and range precautions should be followed.

Thanks for the idea, I can do a bit of a change and have a ring band holding the trunnions, it could be out of copper and the contrast would look good.
Clive

I recommend brass. Copper, will work harden on you, and is a bear to machine with any finish, as it tends to tear if you harden it from cutting. Its OK tho, try it and you will see it is a whole diferent game than any brass.

you may want to read up a bit on brass turning also its a world differient than copper and differient from steel

Take a look at my construction pages for that very gun. This one is 24 inches long (1/5 scale), 1" bore and steel but it may help. With the trunnions below center, you cannot get a great mounting system for them because the bottom is barely in the tube if you leave much wall thickness at the trunnions. Mine are silicon bronzed in place as I used mystery metal and was unsure whether I would have problems welding, which is my preferred method of trunnion attachment. If using brass, I would stay away from any method that uses high heat as you will anneal the brass to its softest state which would not be good for a firing cannon.

Although it would increase the cost of the blank substantially, I think you should machine from solid the whole thing so the trunnions are integral. This greatly complicates manufacture because the trunnions are not symmetrical about the tube and access to the joint is difficult. There would be lots of hand work. But you would have a better piece that way. Steel construction would be easier, and brass plate afterwards. And less expensive.

Thanks for the input, I'm not worried about the machining, I'm a retired machinist. The reason I was looking at brass is because that's what is specified on the plans I bought (they are by Jerry E. Howell), I've always thought that the old naval cannons were bronze. I have no idea what the cost difference between brass and bronze is as I've always just gone to the metals rack and got what was needed, never bought it, I suspect that's the next shock. Steel would be simpler as I have a few lengths lying around but I would have to do something about rust and as it's going to be on display in the lounge brass or bronze is my choice.
Clive

George, the only difference I see in your cannon to mine is the trunnions, mine are on center. I was looking up material strength in my Machinerys Handbook today and was very surprised to see that Phos. Bronze has a greater tensile strength than mild steel. Do you have any links to your cannon being fired?
Clive

Does Barney's Cannons still supply cast barrel blanks?

Al