johnsmachines

machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment. I read every comment and respond to most. n.b. There is a list of my first 800 posts in my post of 17 June 2021, titled "800 Posts"

Tag: Dahlgren XI

Model Dahlgren Gun – 2

My plan to make a model of this 1861/1875 American naval gun had not progressed for 2 months.

I have excellent plans of the barrel, but only tourist photos of the carriage and sloped slide/traversing platform. None of the hundreds of photos on Pinterest, Google Images, Wikipedia, Google Search etc were of the underside, where there had to be mechanical components, which would be vital for a model.

Enquiries to the museum (Patriot’s Point Naval and Maritime Museum), and a succession of official US records departments, museums, naval institutions etc etc had produced only courteous replies, but no drawings or other records relating to this carriage or platform.

Originally the Dahlgren barrel was mounted on a wooden carriage and platform, and I did find some good, original drawings of those. And even an stl file on “Thingiverse” which I 3D printed in PLA.

The 3D printed Dahlgren 11″ model. With homemade ropes. The photo highlights the printing imperfections, which are barely visible in reality. A little more about that model later…

With my failure to obtain decent information about the iron carriage and platform and I was at the point of either abandoning the whole project, or going to South Carolina and personally measuring up an original, or making my model with a wooden carriage and platform and steel barrel of course, using the stl plans from Thingiverse. Unfortunately, going to South Carolina personally is not an option.

Then I had a brainwave.

I posted a plea for help, on the “Ships of Scale” website. Asking for someone, anyone, who lived near the Patriot’s Point Museum, to go to the museum and take some particular photographs and measurements of the original gun.

Lots of views of the plea, and quite a few responses with advice, but no offers to actually take the required photos and measurements.

Then, after 2-3 weeks, a gentleman from Aiken, South Carolina, said that he was prepared to make the 140 mile journey from his home to get the information for me. His name was Jonathan Gerson (mentioned here with permission), and coincidentally he is also building a model of USS Constitution.

BUT, the guns were not at Patriot’s Point Museum. When Jon arrived there, he could see only concrete pads where the guns had been. An enquiry revealed that they had been moved to a soccer stadium a few miles away (why!??). No mention of that change on the museum website, or in several emails from museum staff to me.

So off Jon went to the stadium, where he had some fun photographing and measuring the guns, and even more fun noticing the lady joggers in the vicinity.

In due course I received 45 photographs and some dimensions of the Dahlgren, which were just what I needed. They revealed the undersides and suspected but otherwise unproven evidence of gears and brakes.

One of Jon’s photos. Priceless!

I offered to defray Jon’s expenses, but that was flatly denied because he was “pleased to help a fellow model shipbuilder”. Needless to say, I remain flabbergasted and awed at his generosity. I sent the printed model pictured above as a gift, and received a very nice thankyou in return.

So, I am now able to continue machining the barrel. I have drilled the bore to 16mm, and must enlarge that to 20mm, and then do the rifling while the steel blank is still a cylinder and easily able to be held. (well, fairly easily). I also need to make a thread at the breech to attach the cascable button. And to drill holes for the trunnions. Then the external “soda bottle” shape of the exterior can be turned. None of that could be machined until I knew whether I was making an 11″ smoothbore or a smoothbore converted to an 8″ rifled cannon.

Needless to say, this will be a model, and will not be capable of being fired, for legal reasons. But it will otherwise be as accurate to the original as I can make it.

Now, back to rigging the Constitution.

Another Model Cannon?

When I saw this one, I thought “that is my next model”. (The gun, not the USS Yorktown)

The sleek barrel lines, the low menacing profile, and simple steel shapes and mechanicals are perfect. And it has history, and is contemporary with some of my other models.

Patriots Point Naval and Maritime Museum

40 Patriots Point Road
Mount Pleasant, South Carolina 29464

It is a Dahlgren 11″ bore, muzzle loader, 1861.

I have collecting as much information as possible. Fortunately, the patent diagram lists the dimensions and profiles of the barrel. The carriage and slide and mechanicals look fairly simple in the photos, but so far I have been unable to find any diagrams or plans of those. Might need to take a tape measure to South Carolina to get those.

The following is cut and pasted from the listing of the Patriots Point Naval and Maritime Museum

Civil War Cannons At Patriots Point

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As visitors pull into the parking lot at Patriots Point, they may notice four large cannons on the shore pointed at the USS Yorktown. Some astute observers will recognize them as Dahlgren guns.

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The guns take their name from a career Naval officer, Rear Admiral John Dahlgren(opens in a new window), who was especially qualified in the development of  ordnance for the United States Navy. His gun design bore his name and had the distinctive  shape of a soda bottle. The four Dahlgren guns at Patriots Point were made at Builders Foundry in Providence, Rhode Island in 1863. Their original numbers were No. 63, 64, 67 and 69. They were originally 11 inch Dahlgrens  and weighted around 15,750 pounds (each is slightly different).  These 11 inch Dahlgrens could fire a shot that weighted 170 pounds.

The Patriots Point Dahlgrens were pivot guns, so they would have been deployed aboard ships such as New Ironsides(opens in a new window) and Kearsage(opens in a new window).  We are still researching the National Archives to find their Civil War service history. Carriage guns were placed in the new ironclad monitors like the Monitor(opens in a new window) (2 11 inch Dahlgrens) and the Keokuk(opens in a new window) (2 11 inch Dahlgrens).The Keokuk led the attack on Fort Sumter in April 1863 and was badly damaged. She sunk off of Morris Island and the Confederates were successful in raising one of her guns, which today is on display at the Battery in downtown Charleston, South Carolina.

Back to me now…..

At my usual model cannon scale of 1:10, I will need a chunk of steel over 81mm diameter, and 400mm long for the barrel, and a long heavy boring bar for the bore. Much of the carriage and slide will be machined or laser cut. Some castings might be required.

If I cannot obtain drawings or plans of the carriage and slide, I might substitute those from the USS Monitor, which has a notable place in world history. More about the history later of which ever is the choice.

This is a 3D CAD of the USS Monitor carriage and slide, drawn by SOS reader Carlo Cesani “the artillerist”.

The USS Monitor has been salvaged and is being restored, along with the gun turret and 2 Dahlgren XI guns. Those are 11″ smooth bore, muzzle loaders almost identical with the ones at Patriot Point except that the PP ones are rifled. Plans of the Monitor and its guns are available online, which is a big plus.

Someone’s model of Monitor’s gun turret and Dahlgrens. (attribution will be added if I can locate it)