1:28 Scale 9" Dahlgren Gun

My great great grandfather manned one of the IX Dahlgren guns on the CSS Virginia during the Civil War. His gun was one of the two hot shot guns which were used to shoot red hot cannonballs into wooden ships to set them on fire. The USS Congress was destroyed using this method. Anyway, I had a bit of 1018 round bar left from a previous project so I decided to make a scaled down IX Dahlgren Gun.


This will probably be a rather lengthy build, so here are some navigational links to distinctly different parts of the build:
The Barrel
The Carriage
The Implements
The Recoil System
The Shooting Platform
Videos



The Barrel

First I drilled the .32" bore and turned the outside profile. The stubby cylinder at the left end will be formed into the cascabel later. It'll have a horizontal hole for breeching ropes, and a vertical tapped hole for the elevation screw.



Next I made the two trunnion/rimbase assemblies and finished the cascabel. The hole for the elevation screw is threaded for #4-40.



It took 3 hours to grind out the .375" pocket for the trunnions with a Dremel tool and a diamond burr. I really need to get a milling machine, this operation would have take a quarter the time and be much more precise. As it is I got the trunnion pockets a sixteenth out of line, but it's not too noticeable.



Next I silver brazed the trunnions on. I first put a dab of silver solder in the trunnion pocket, then clamped the trunnion/rimbase assembly on and heated the cannon to a dull orange. The solder melted and flowed around the trunnion locking it in place. A good thing about 1018 steel is that it doesn't readily harden so heating it to dull orange won't make it brittle.





The Carriage

After brazing the trunnions on, I started the Marsilly Style carriage. It's not like the normal four wheeled naval gun carriages you see. It has two wheels at the front, and skids on the back. These carriages were designed to be used with heavy cannons where the friction from the rear skids would help tame the recoil.



Here's the finished carriage sitting on top of a powder can. I still need to make the trunnion straps and paint it.



The trunnion straps are installed on the carriage and everything is painted. I made the straps from a piece of annealed rake tine. The front nails can be pulled out so the barrel can be removed for cleaning.



The Implements

Here's a rammer, sponge, and two handspikes. Handspikes were basically wooden pry bars that the gun crew used to raise the cannon's breech so the elevation screw could be adjusted. They also used them to help move the carriage.



The Recoil System

I spliced an eye onto the end of the breech rope. I started it out like a molly hogan to keep the ends from flopping around. I used a large knitting needle like a marlinspike to get the strands under the right thread. I think it turned out pretty good, especially considering how small it is.



For the other end of the breech rope I doubled it back and secured it with round seizing. I used black sewing thread and a dab of superglue to keep the end from working loose.



Next I made the shackles to hold the breech rope. Each shackle consists of 3 piece. Two rings with a tail separated by a spacer. I tacked everything together with a small stick welder, filed the welds down, and painted it black. The loop on the breech rope goes between the two rings and a bit of a nail drops through the shackle and secures everything.



Next I drilled a hole into the side of the ship and epoxied the shackles in place. There's not much room under there and I had to mount them low enough so the pin won't jam against the underside of the shield.



The Shooting Platform

Next I thought I'd make a scale cross section of the CSS Virginia. The ship's armored casemate consisted of a lamination of overlapping yellow pine, oak, and wrought iron planks on a 36º angle to deflect enemy shot. The innermost layer consisted of 16" rafters made of yellow pine running vertically. Next 4" thick yellow pine planks were bolted on longitudinally. Then a 4" layer of oak running vertically followed by a longitudinal layer of 2x8" wrought iron. The final layer of 2x8" wrought iron was placed vertically with countersunk bolts. In battle a thick coat of grease was smeared on the shield to further help deflect shot.



Here's the third layer of oak laid vertically. I've also enlarged the port hole to accommodate the gun when fully run out. It's pretty interesting to see just how little room there was around the gun due to the sloping shield.



Here's the fourth layer of iron running longitudinally. Every one of those strips were cut with a circular saw and abrasive disk. The edges are filed smooth. Then holes are center punched, drilled, and then countersunk. Finally the armor plates are nailed onto the wooden casemate. It's a ton of work and there's still an entire layer to go on after this.



The fourth layer is done and I've started on the final layer of vertical iron. I've also put some primer on to ward off any rust.



Plugging away at the final layer of iron. In addition to all the work that goes into making the individual plates, I have to drill clearance holes through the previous layer of metal for the nail. Also, I can't drill into the wood or else the nail won't hold.



Finally the shooting platform is done! It's made of 37 pine and oak boards, 270 nails, and 40 metal plates with 182 holes. Perhaps one day I'll have to make the sloping shield for the other side of the ship and a scale 6.4" Brooke rifle...



Videos

This was the first shot. I hadn't drilled the vent yet, so I was forced to fire it with a fuze out of the muzzle. I couldn't find any fuse long enough, so I used a strip of paper, spray adhesive, and FFFg black powder.



I took the mini Dahlgren to the gun range to see if I could hit any targets with it. As soon as I set it up a whole flock of guys came to look at it. I meant to get a video of each shot, but with everyone standing around I forgot until the last shot. I think a centerfire rifle went off just as my cannon did, so the report sounds off. I was using 7-8 grains FFg.



Here's the first test using the shooting platform. The first shot was 10 grains FFFg and a wad of paper. It didn't recoil much, but the flame coming out the vent singed the wood. The second shot was 8 grains FFFg and a .32 caliber lead ball. The recoil was pretty violent so I reduced the charge to 5 grains for the third shot. I hit a 1/8" piece of hot rolled steel but it didn't even dent it. :(