Armstrong RML

Some images of what I am planning to be my next model build.  As mentioned in a recent post, I photographed and took lots of measurements of this Rifled Muzzle Loader at Port Fairy, and have been searching the web for more information.  It is said to be an 80 pounder, but the bore (6.3″) is more consistent with a 64 pounder.  Can anyone shed any light on the discrepancy?

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Yes, there will be some interesting machining challenges.

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Not looking forward to all of that riveting.  Considering options.

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Most of the photos were taken with a Panasonic Lumix camera, but some, like this one, were with my iphone, using an App named “My Measures” which accepts annotations and measurements.  The barrel “diameters” above are actually circumferences.  And the “19” is the plate thickness.

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The emblem on the barrel surface.  I am hoping to engrave this on the model, but there would be a lot of time cleaning up the image.

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A web search turned up this image, which will be easier to clean up for laser engraving on the model.

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And some basic diagrams of similar design

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The rifling grooves are 1″ wide.  3 of them.  How to make them?

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I asked about rifling grooves at a GSMEE meeting, and Rudi showed me how it is done.  He made these 2 rifling tools.   They are pushed through the bore to create the grooves.  The bottom tool was most succesful, because it has a pilot diameter.  But, the tools cannot be pulled backwards, so both ends of the bore must be open.  But what about the cascable end of the cannon.  It is not a breach loader.

Then the penny dropped…..I remembered seeing this diagram…

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The cascabel screws into the barrel.  That opening will allow me to broach the rifling.  I do not know how the rifling was made in 1866!  (does any reader have information on that point?)  Note also that these barrels were usually made with some concentric tubes of steel.  I expect that the model will be one piece of steel, with the trunnions silver soldered.

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And I have started drawing up the cannon, massaging the field measured dimensions (which were obtained with a builders’s tape measure)…

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And doing gear calculations for the gear train and rack.  Lots more detail to go into the drawing and plans.   And thinking about construction methods meanwhile.  Now who has a metal sintering 3D printer for loan?