G.N.R. Saddle Tank

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 This beautiful little 0-4-0 Saddle Tank in Great Northern style was described by Henry Greenly in the February 1910 edition of  Models, Locomotives and Railways. Here it is, 114 years later, running with a modern chassis and mechanism. WH Jubb described a live steam version using the same castings in the December 1911 edition, but that model has yet to come to light.


Henry Greenly's GN Style 0-4-0 saddle tank, made before the Great War and now running with 3D printed wheels, gearbox and underframe.

In his article, Greenly describes the model as having a cast aluminium saddle tank, and so it is in this model. The design was listed in the 1911 edition of the Bassett Lowke Gauge 2 catalogue as available in clockwork or electric. The surviving model came to me from Ned Williams who inherited it from Francis Ashley. The model had a modern chassis and this 3D design is intended to more closely replicate the original design, as shown in Greenly's 1910 drawing.

The new chassis has sprung hornblocks as developed for the Greenly 0-6-6-0. Note how the frame plate is thinned in vicinity of the springs to allow 4.5mm dia springs. The gearbox has plain 1/4" bearings to fit between the hornblocks. The motor is Mabuchi RS-385PV-2270 and power 2x 18650. The body design is based on Greenly's drawing and is slightly longer than the surviving model. The ruling wall thickness is 2.5mm. It has been ordered experimentally in both Nylon SLS and Resin. An accessory sprue carries handrail knobs, coupling hooks, smokebox dart and buffers.



Page from the 1911 'Gauge 2&3' Bassett Lowke catalogue.

The model was originally intended to be either clockwork or electrically powered and Greenly shows what appears to be a permanent magnet motor in his drawing: Permanent magnet motors were still rare in 1910 because the materials available (just mild steel) had poor 'coercivity', meaning that they easily became demagnetised. Greenly probably shows a permanent mgnet motor because there would not have been room in the model for a seperate reversing mechanism which would have been needed with the typical wound field motors of the time.

The surviving model was never clockwork, and it is unclear if it is of Bassett Lowke origin  The detail is very similar to Greenly's 1910 drawing although the model is cut down in height, perhaps to suit a customer requirement.



Greenly's original drawing in 'MR&L', Feb 1910.


Unfortunately the original motor and underframe have not survived and so a replacement following Greenly's outline has been made. The modern '385' style motor has rare earth magnets which would have seemed like magic in 1910 and the wheels and frames have been 3D printed in SLS (Sintered Nylon) material. The design incorporates springing and ball bearings and uses two '18650' Li-ion cells for power giving several hours running time.



Underside view showing 3D Printed wheels, frames and gearbox.

And Now ... A Replica!

Subsequent to fitting the new running gear to Greenly's original model, it was decided to use the design as a testbed for a large scale 3D printed locomotive, the first ever 3D printed locomotive in Gauge 2! The resulting print was made in SLS Nylon, but also in resin for comparison purposes. Here is the nylon version, wrapped in colour printed vinyl:



The replica model, body 3D one piece printed in sintered nylon.


Built to Greenly's drawing, the replica comes out slightly taller than the original. Quite possibly Bassett Lowke cut the model down slightly to improve clearances. The replica model sits well with it's authentic counterpart and is quite possibly the only Gauge 2 locomotive made in the 21st century and certainly the first and only Gauge 2 model made by 3D printing - so far! Here are the two locos together:



114 years seperate these almost identical models.


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