Although I have written about the development of the Stars in an earlier post and have modelled several of them, as described in another post, I have not, for inexplicable reasons, ever modelled the most iconic ‘Star’ of all – North Star – the true ancestor of all the early Broad Gauge engines

In most respects ‘North Star’ had very similar dimensions to ‘Evening Star’, which was delivered around 2 years later. As regular readers of my blog will know, I construct most of my models by extruding from a drawing that I import into ‘Autodesk Fusion’ (formerly known as Fusion 360) as a ‘canvas’. This frees me from the need to make any measurements for myself but it also means that the final result is critically dependent on the accuracy of the original drawing.

I have written before that drawing errors are frequent, either in the drawing itself or the way it has been reproduced when printed. I almost fell foul of this problem once again with the present model!

There are several drawings of ‘North Star’ in Mike Sharman’s book of Broad Gauge engines, published by Oakwood Press, from which I chose one that was uncluttered but contained the relevant information that I needed to create a model. The drawing was derived from an article in The Locomotive Magazine, 1901, where it carries the initials GFB (for G.F.Bird). It didn’t need much examination to show that there are major errors in this drawing. The distance between the driving wheels and front carrying wheels is considerably longer than that between the driving and trailing wheels, which does not agree with the published specifications for the engine.

When I imported this drawing into ‘Fusion’ and placed my model of Evening Star in front of it, there were many other significant discrepancies. I think it is unfortunate that so many of the drawings by Bird have been widely published, since I have found errors in several of the ones I attempted to use.

I turned instead to a drawing in the book by E.L.Ahrons ‘The British Steam Locomotive 1825-1825’ which is admittedly of the replica that was built in 1925 but I feel that the builders of that replica took great care to use the best information obtainable. My confidence was borne out in that, when I imported this drawing as a canvas into ‘Fusion’, it was an excellent match to my previous model of ‘Evening Star’.

Drawing of North Star overlaid on my model of ‘Evening Star’

This comparison showed that I could re-use many parts from ‘Evening Star’ in creating my model of ‘North Star’ – in particular the boiler, smokebox, frames, and wheels. I needed to create a new round-topped firebox and a new set of boiler fittings, including a dome and safety valve casings.

Fortunately the drawings in the Ahrons book included end-elevations, from which I could extrude the profile of the firebox. I then used the ‘fillet’ tool in ‘Fusion’ to produce the brass trim at each end of the firebox. After that, I drew a single plank on one side of the firebox and used the ‘pattern on path’ tool to repeat the planking over the sides and the rounded top of the firebox – the end result is shown below

Round-top Firebox with Wood Lagging

Note that I have exaggerated the width of the gaps between the planks so that these will remain visible when printed in 4 mm scale.

I created all the boiler fittings by the method of tracing the outline from the drawing and then using the ‘revolve’ tool in ‘Fusion’ to create a cylindrical body.

Profiles before ‘Revolving’ about the marked Axes

And so, with remarkably little new construction, I was able to add ‘North Star’ to my existing collection of ‘Stars’

My model of ‘North Star’

The similarity with ‘Evening Star is apparent when I place the two models together:

Comparison between ‘Evening Star’ and ‘North Star’

These models share all major components.

Mike