Dimensions of Quoins

J

JayOh

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Hello,
I'm new to this august group, and I go by the name of John.
Some considerable years ago we salvaged a bronze prop shaft from a beached wreck. After some discussion, we decided to machine four bronze 18th c. cannon from the material. One of our group, long gone now, was an ex army, retired gunsmith and black powder expert, along with other things that go bang. He span up four, working, 6 pdr cannon from this material, to the scale of 3/4 calibre. His own cannon was mounted as a field artilliary piece. I now have the other three guns, which I propose to mount on Royal Navy carriages and displayed on interlocking, individual, sections of a gundeck.

Now to the nub of the matter. I have scaled the all aspects of the gun carriages to calibre, according to, "John Robertson's Treatise", except for the quoins. I wonder if anybody has, or knows where to find, in relation to calibre, the dimensions of the quoin? In particular the angle of the wedge. Robertson does not mention any dimensioning of the quoin, apart from a carronade, and even then, they seem to be a rectangular block, rather than a wedge.

If anybody has any ideas on this score, I would be eager to hear of them.
 
Sorry, but I have all that. I have scaled everything to the calibre. Highly complex to set up the original formula, but very clever to put into practice.

My only problem, as I stated, is the dimensions of the Quoin.
 
JayOh said:
Sorry, but I have all that. I have scaled everything to the calibre. Highly complex to set up the original formula, but very clever to put into practice.

My only problem, as I stated, is the dimensions of the Quoin.
Click to expand...
the quoin can be calculated in relative proportion to the stool bed rear axletree and bolster.
 
Thank you for your efforts.

I had another look around at some of the diagrams/images around the web. The quoin seems to be governed by the hieght of the breach, above the stool, when the gun is depressed to its maximum downward angle of 12 degrees.

I am currently transcribing Mr Robertsons work into a spreadsheet, so that, when the calibre of a cannon is entered, all the dimensions of the carriage are calculated. I will post the results once they are completed. In due course, I will also post pictures of the cannon that I am currently working on.
 
This is my first spreadsheet iteration of John Robertson's treatise concerning the dimensioning of Royal Navy gun carriages.

Initially I have kept, for the most part, to the original form of English nomenclature and layout. In the future I intend to convert the language into a more readable form for modern eyes. This will be once I have built my cariages and have a fuller understanding.


The only information that it requires is the overall length of the gun, in inches, and calibre (bore diameter). The spreadsheet then calculates all dimensions of the components needed for the gun carriage.

If anyone would like a copy, I will be happy to make it availalble.
 

Attachments

  • Cannon Dimensions.pdf
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Hmmm…not to be simplistic but from what I have learned the angle of the Quoins depends on the desired arc of the gun muzzle from top of arc and no Quoin inserted to the bottom of the arc with Quoin fully inserted. That arc is dependent on the opening of the gun port as well as the set of the gun in the carriage. Thus, with the muzzle fully depressed one measures the distance from the gun breach to the gun carriage base to achieve the height of the Quoin then taper the Quoin to complete the aiming arc of the muzzle. Anyway…this is what I have learned to model gun Quoins. I have not seen any dimensional suggestions for making quoins in my research…
 
Jimsky said:
Usually, the trunnion diameter equals the caliber. Here is the image that may help...

View attachment 407806

View attachment 407807

View attachment 407808
Click to expand...
1. The quoin would fit on top of the stool bed.
2. The size was not standardized. The size varied depending upon the size of the gun carriage, not the gun.
A given barrel could be used on many different size carriages.
3. The range in size would be about 6 to 16 inches long and angled about 1 inch to 6 inches thick.
4. The size was finally determined by simply measuring the declination and elevation required of the gun barrel.
5. The carpenter would finally cut the quoin (and/or rebuild the gun carriages) to fit the target the "ball" was expected to hit.
6. Experience was a vital factor in gunnery.
 
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Thank you Jim, I have all dimensions for the carriage itself and have produced a 1st draft spreadsheet to calculate the scantlings for carriages. See above
 
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